Flexible Assembly of Engineered Tetrahymena Ribozymes Forming Polygonal RNA Nanostructures with Catalytic Ability

Ribozymes with modular architecture constitute an attractive class of structural platforms for design and construction of nucleic acid nanostructures with biological functions. Through modular engineering of the Tetrahymena ribozyme, we have designed unit RNAs (L-RNAs), assembly of which formed ribozyme-based closed trimers and closed tetramers. Their catalytic activity was dependent on oligomer formation. In this study, the structural variety of L-RNA oligomers was extended by tuning their structural elements, yielding closed pentamers and closed hexamers. Their assembly properties were analyzed by electrophoretic mobility shift assay (EMSA) and atomic force microscopy (AFM).     

Thermophysical properties of molten core materials: Zr–Fe alloys measured by electrostatic levitation

In order to investigate the progression of a core meltdown accident, it is necessary to understand the behavior of molten core materials. Zr–Fe alloys are one of the low-melting-temperature liquid phases that are thought to form in the early stages of bundle degradation. The objective of this study is to measure the thermophysical properties of Zr–Fe liquid alloys. Alloy samples with a composition of Zr_1?xFe_x (x = 0.12, 0.24, and 0.50) were synthesized by arc melting, and their density, viscosity, and surface tension were measured using an electrostatic levitation technique. The results indicate that the density of Zr–Fe liquid alloys can be estimated by a linear combination of the measured or extrapolated densities of pure Zr and Fe. The viscosities of the Zr–Fe liquid alloys can be roughly estimated by extrapolating those of Zr to lower temperatures, although this method tends to underestimate the viscosity of alloys, especially for eutectic compositions. The values of the Zr–Fe liquid alloys’ surface tensions are close to those of pure Zr.     

Cu2O-based solar cells using oxide semiconductors

We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO (AZO)/n-type oxide semiconductor/p-type Cu₂O heterojunction solar cells fabricated using p-type Cu₂O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu₂O sheets under various deposition conditions using a pulsed laser deposition method. In Cu₂O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa₂O₄ thin-film layer. In most of the Cu₂O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO-MgO and Ga₂O₃-Al₂O₃ systems, higher conversion efficiencies (η) as well as a high open circuit voltage (V_oc) were obtained by using a relatively small amount of MgO or Al₂O₃, e.g., (ZnO)_0.91-(MgO)_0.09 and (Ga₂O₃)_0.975-(Al₂O₃)_0.025, respectively. When Cu₂O-based heterojunction solar cells were fabricated using Al₂O₃-Ga₂O₃-MgO-ZnO (AGMZO) multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high V_oc of 0.98 V and an η of 4.82% were obtained. In addition, an enhanced η and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu₂O heterojunction solar cells fabricated using Na-doped Cu₂O (Cu₂O:Na) sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an η of 6.25% and a V_oc of 0.84 V were obtained in a MgF₂/AZO/n-(Ga₂O₃-Al₂O₃)/p-Cu₂O:Na heterojunction solar cell fabricated using a Cu₂O:Na sheet with a resistivity of approximately 10 Ω·cm and a (Ga_0.975Al_0.025)₂O₃ thin film with a thickness of approximately 60 nm. In addition, a V_oc of 0.96 V and an η of 5.4% were obtained in a MgF₂/AZO/n-AGMZO/p-Cu₂O:Na heterojunction solar cell.     

Fractal analysis of the treeing process from luminous dischargeimage and measurement of discharge magnitude

The purpose of this study is to analyze the growth of trees generated in PMMA from the apex of a void created by a needle tip. The analysis was based on fractal theory. In the measurement system, PMMA blocks were used with electrodes consisting of a needle and a plate. One cycle of an applied ac voltage was divided into twenty successive phase angle sections, labeled φ1, φ2, ..., φ20, from one negative peak to the next negative peak of the applied voltage. The quantitative evaluation of the fractal dimension D of the luminous discharge pattern was performed for each section, particularly, for the sections φ7, 8, 9, 17, 18 and 19 where the discharge luminescence reached around the tip of the tree. It was noted that some samples revealed substantially different tree patterns even under the same measurement conditions. The reasons for the different trees have been investigated by determining D and attempting to correlate tree growth and the change of tree length with aging. When D of the discharge luminescence at φ7, 8, 9, 17, 18 and 19 were large, luminescence with complex branches were generated. The present results indicate that tree growth and branching depend on the discharge at φ7, 8, 9,17, 18 and 19     

Preparation of PVDF/poly(tetrafluoroethylene‐co‐vinyl alcohol) blend membranes with antifouling propensities via nonsolvent induced phase separation method

Poly(vinylidene fluoride) (PVDF) was blended with a new amphiphilic copolymer, poly(tetrafluoroethylene‐co‐vinyl alcohol) [poly(TFE‐VA)], via non‐solvent induced phase separation (NIPS) method to make membranes with superior antifouling properties. The effects of the VA/TFE segment ratio of the copolymer and the copolymer/PVDF blend ratio on the properties of the prepared membranes were studied. Membranes with similar water permeabilities, surface pore sizes, and rejection properties were prepared and used in bovine serum albumin (BSA) filtrations with the same initial water flux and almost the same operating pressure, to evaluate the sole effect of membrane material on fouling propensity. While the VA/TFE segment ratio strongly affected the membrane antifouling properties, the effects of the copolymer/PVDF blending ratio were not so drastic. Membrane surface hydrophilicity increased, and BSA adsorption and fouling decreased upon blending a small amount of amphiphilic copolymer with a high VA/TFE segment ratio with PVDF (copolymer/PVDF blending ratio 1:5). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43780.     

Novel virtual OCS in OPS data center networks

This paper considers a novel virtual optical circuit switching (VOCS) scheme for data center networks where short flows are transmitted via optical packet switching (OPS), while long flows with reliability requirement are transmitted via VOCS. VOCS preserves the advantage of optical circuit switching (OCS) for reliable communication, while it overcomes the disadvantage of OCS in terms of low link utilization. In the VOCS/OPS scheme, idle periods of the virtual circuits can be used by OPS, which thus enhances the overall performance. Simulations on a six-dimensional torus topology data center network with 4096 (=4\(^6\)) nodes are conducted for the performance evaluation. We have observed that, compared to OCS, VOCS has much less adverse impact on the performance of OPS. Furthermore, quite a large number (i.e., 2048) of virtual circuits can be set up with little affect on the OPS performance.     

Numerical analysis of feedforward position control for non-pulley musculoskeletal system: a case study of muscular arrangements of a two-link planar system with six muscles

In a musculoskeletal system like a tendon-driven robot, redundant actuation is necessary because muscles (or mechanical parts such as tendons) can transmit tension only unidirectionally. This redundancy yields internal force among muscles, which has a particular field of potential energy. Using internal force as a feedforward input, a musculoskeletal system can achieve feedforward position control with no sensory feedback. This paper studies the feedforward position control coming from the redundancy for a non-pulley musculoskeletal system. Targeting a planar two-link system with six muscles as a case study, the motion convergence depending on the muscular arrangement is examined quasi-statically. The results point out that the convergence is extremely sensitive to the muscular arrangement, and adding small offsets for the muscular connected points can remarkably improve the positioning performance.     

Monolithic integration of Pb(Zr,Ti)O3 thin film based resonators using a complete dry microfabrication process

Monolithic fabrication of lead zirconate titanate [Pb(Zr,Ti)O₃ or PZT] based thin film resonant devices such as microcantilevers, Lamb wave and bulk acoustic wave resonators are demonstrated. High-performance PZT thin films with a thickness of 2.6 μm are prepared on a silicon on insulator wafer by a sputtering deposition process. A highly selective reactive ion etching process is employed for micro-patterning of PZT, platinum electrodes, and SiO₂ insulation layer. Self-actuation of the PZT microcantilevers is demonstrated and the frequency response is characterized using a laser Doppler vibrometer. The frequency response of the Lamb wave resonator is evaluated by measuring its transmission characteristic using a network analyzer. For a Lamb wave resonator with a length of 240 μm and an interdigital period of 80 μm, the 1st order and 2nd resonance frequencies are 15.3 and 41.8 MHz, respectively.     

A 5291‐ppi organic light‐emitting diode display using field‐effect transistors including a c‐axis aligned crystalline oxide semiconductor

C‐axis‐aligned crystalline‐oxide semiconductor field‐effect transistor (CAAC‐OS FET) can be scaled down to a width and a length of 60 nm. We fabricated an organic light‐emitting diode (OLED) display with more than 5000 ppi, which is required in virtual reality (VR) display applications, using CAAC‐OS FETs as the backplane.     

Exponential family tensor factorization: an online extension and applications

In this paper, we propose a new probabilistic model of heterogeneously attributed multi-dimensional arrays. The model can manage heterogeneity by employing individual exponential family distributions for each attribute of the tensor array. Entries of the tensor are connected by latent variables and share information across the different attributes through the latent variables. The assumption of heterogeneity makes a Bayesian inference intractable, and we cast the EM algorithm approximated by the Laplace method and Gaussian process. We also extended the proposal algorithm for online learning. We apply our method to missing-values prediction and anomaly detection problems and show that our method outperforms conventional approaches that do not consider heterogeneity.