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M. Yamada, Y. Shiratsuchi, H. Kambe, K. Kudo, S. Yamada, K. Sawano, R. Nakatani, and K. Hamaya, Journal of Applied Physics 129, 183901 (2021); https://doi.org/10.1063/5.0048321., Using artificially controlled ferromagnet (FM)-semiconductor (SC) interfaces, we study the decay of the nonlocal spin signals with increasing temperature in SC-based lateral spin-valve devices. When more than five atomic layers of Fe are inserted at the FM/SC interfaces, the temperature-dependent spin injection/detection efficiency (P inj /det) can be interpreted in terms of the T3/2 law, meaning a model of the thermally excited spin waves in the FM electrodes. For the FM/SC interfaces with the insufficient insertion of Fe atomic layers, on the other hand, the decay of P inj /det is more rapid than the T3/2 curve. Using magneto-optical Kerr effect measurements, we find that more than five atomic layers of Fe inserted between FM and SC enable us to enhance the ferromagnetic nature of the FM/SC heterointerfaces. Thus, the ferromagnetism in the ultra-thin FM layer just on top of SC is strongly related to the temperature-dependent nonlocal spin transport in SC-based lateral spin-valve devices. We propose that the sufficient ferromagnetism near the FM/SC interface is essential for high-performance FM-SC hybrid devices above room temperature.

M. Yamada, Y. Shiratsuchi, H. Kambe, K. Kudo, S. Yamada, K. Sawano, R. Nakatani, and K. Hamaya, Journal of Applied Physics 129, 183901 (2021); https://doi.org/10.1063/5.0048321., Using artificially controlled ferromagnet (FM)-semiconductor (SC) interfaces, we study the decay of the nonlocal spin signals with increasing temperature in SC-based lateral spin-valve devices. When more than five atomic layers of Fe are inserted at the FM/SC interfaces, the temperature-dependent spin injection/detection efficiency (P inj /det) can be interpreted in terms of the T3/2 law, meaning a model of the thermally excited spin waves in the FM electrodes. For the FM/SC interfaces with the insufficient insertion of Fe atomic layers, on the other hand, the decay of P inj /det is more rapid than the T3/2 curve. Using magneto-optical Kerr effect measurements, we find that more than five atomic layers of Fe inserted between FM and SC enable us to enhance the ferromagnetic nature of the FM/SC heterointerfaces. Thus, the ferromagnetism in the ultra-thin FM layer just on top of SC is strongly related to the temperature-dependent nonlocal spin transport in SC-based lateral spin-valve devices. We propose that the sufficient ferromagnetism near the FM/SC interface is essential for high-performance FM-SC hybrid devices above room temperature.

Kinetic analysis of CO2 gasification by thermogravimetry was examined employing chars from a Victorian lignite. The gasification of char from the rigorously acid-washed lignite was extremely slow. More than 600 min was required for the complete gasification as a result of a near absence of inherent alkali and alkaline earth metallic (AAEM) species. It was nonetheless necessary to strictly choose the following conditions for eliminating the mass transfer effect: an initial mass of char of <1.3 mg, a particle size of char of <125 μm, and a total gas flow rate of ≥1000 mL standard temperature and pressure min–1. Such requirement arose from the inhibition of non-catalytic gasification by CO within the char particle. On the other hand, the char from the original lignite was gasified much faster than the non-catalytic gasification and completed within 50 min by catalysis of the inherent AAEM species. The measured rate of catalytic gasification was, unexpectedly, independent of the initial char mass and particle size and gas flow rate. This was reasonably explained by no or little importance of CO inhibition in the catalytic gasification. This study has also drawn another important conclusion that the non-catalytic gasification obeyed first-order kinetics with respect to the char mass. The rate constant was steady over the entire range of char conversion, while both the specific surface area and carbon-type distribution of the char varied along with the conversion.

Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900°C by applying a new method to continuously monitor the char surface activity. Benzene vapor was continuously forced to pass through a micro fixed bed of char with residence time as short as 7.6 ms, and then detected continuously by a flame-ionization detector. Results showed the presence of two different types of char surfaces; consumptive Type I surface and non-consumptive (sustainable) Type II surface. Type I surface of a partially CO2-gasified char had an capacity of carbon deposit from benzene over 20 wt%-char and an initial activity (represented by a first-order rate constant) as high as 160 s-1. Both of them decreased with increasing carbon deposit due to consumption of micropores accessible to benzene, and finally became zero leaving Type II surface that had a very stable activity with rate constant of 4 s-1. The chars without gasification had capacities of Type I surfaces smaller by two orders of magnitude than the partially gasified char, while the Type II surfaces had activities similar to that of the partially gasified char. It was found that Type II surface converted benzene into not only carbon deposit but also diaromatics and even greater aromatics. Composition of the greater aromatics was unknown because they were deposited onto the reactor wall immediately after passing through the char bed.

Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900°C by applying a new method to continuously monitor the char surface activity. Benzene vapor was continuously forced to pass through a micro fixed bed of char with residence time as short as 7.6 ms, and then detected continuously by a flame-ionization detector. Results showed the presence of two different types of char surfaces; consumptive Type I surface and non-consumptive (sustainable) Type II surface. Type I surface of a partially CO2-gasified char had an capacity of carbon deposit from benzene over 20 wt%-char and an initial activity (represented by a first-order rate constant) as high as 160 s-1. Both of them decreased with increasing carbon deposit due to consumption of micropores accessible to benzene, and finally became zero leaving Type II surface that had a very stable activity with rate constant of 4 s-1. The chars without gasification had capacities of Type I surfaces smaller by two orders of magnitude than the partially gasified char, while the Type II surfaces had activities similar to that of the partially gasified char. It was found that Type II surface converted benzene into not only carbon deposit but also diaromatics and even greater aromatics. Composition of the greater aromatics was unknown because they were deposited onto the reactor wall immediately after passing through the char bed.

Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.

M. Yamada, Y. Shiratsuchi, H. Kambe, K. Kudo, S. Yamada, K. Sawano, R. Nakatani, and K. Hamaya, Journal of Applied Physics 129, 183901 (2021); https://doi.org/10.1063/5.0048321., Using artificially controlled ferromagnet (FM)-semiconductor (SC) interfaces, we study the decay of the nonlocal spin signals with increasing temperature in SC-based lateral spin-valve devices. When more than five atomic layers of Fe are inserted at the FM/SC interfaces, the temperature-dependent spin injection/detection efficiency (P inj /det) can be interpreted in terms of the T3/2 law, meaning a model of the thermally excited spin waves in the FM electrodes. For the FM/SC interfaces with the insufficient insertion of Fe atomic layers, on the other hand, the decay of P inj /det is more rapid than the T3/2 curve. Using magneto-optical Kerr effect measurements, we find that more than five atomic layers of Fe inserted between FM and SC enable us to enhance the ferromagnetic nature of the FM/SC heterointerfaces. Thus, the ferromagnetism in the ultra-thin FM layer just on top of SC is strongly related to the temperature-dependent nonlocal spin transport in SC-based lateral spin-valve devices. We propose that the sufficient ferromagnetism near the FM/SC interface is essential for high-performance FM-SC hybrid devices above room temperature.

M. Yamada, Y. Shiratsuchi, H. Kambe, K. Kudo, S. Yamada, K. Sawano, R. Nakatani, and K. Hamaya, Journal of Applied Physics 129, 183901 (2021); https://doi.org/10.1063/5.0048321., Using artificially controlled ferromagnet (FM)-semiconductor (SC) interfaces, we study the decay of the nonlocal spin signals with increasing temperature in SC-based lateral spin-valve devices. When more than five atomic layers of Fe are inserted at the FM/SC interfaces, the temperature-dependent spin injection/detection efficiency (P inj /det) can be interpreted in terms of the T3/2 law, meaning a model of the thermally excited spin waves in the FM electrodes. For the FM/SC interfaces with the insufficient insertion of Fe atomic layers, on the other hand, the decay of P inj /det is more rapid than the T3/2 curve. Using magneto-optical Kerr effect measurements, we find that more than five atomic layers of Fe inserted between FM and SC enable us to enhance the ferromagnetic nature of the FM/SC heterointerfaces. Thus, the ferromagnetism in the ultra-thin FM layer just on top of SC is strongly related to the temperature-dependent nonlocal spin transport in SC-based lateral spin-valve devices. We propose that the sufficient ferromagnetism near the FM/SC interface is essential for high-performance FM-SC hybrid devices above room temperature.

The aim of this study was to review the literature on front crawl swimming biomechanics, focusing on propulsive and resistive forces at different swimming velocities. Recent studies show that the resistive force increases in proportion to the cube of the velocity, which implies that a proficient technique to miminise the resistive (and maximise the propulsive) force is particularly important in sprinters. To increase the velocity in races, swimmers increase their stroke frequency. However, experimental and simulation studies have revealed that there is a maximum frequency beyond which swimmers cannot further increase swimming velocity due to a change in the angle of attack of the hand that reduces its propulsive force. While the results of experimental and simulation studies are consistent regarding the effect of the arm actions on propulsion, the findings of investigations into the effect of the kicking motion are conflicting. Some studies have indicated a positive effect of kicking on propulsion at high swimming velocities while the others have yielded the opposite result. Therefore, this review contributes to knowledge of how the upper-limb propulsion can be optimised and indicates a need for further investigation to understand how the kicking action can be optimised in front crawl swimming.Abbreviations: C: Energy cost [kJ/m]; Ė: Metabolic power [W, kJ/s]; Fhand: Fluid resultant force exerted by the hand [N]; Ftotal: Total resultant force [N] (See Appendix A); Fnormal: The sum of the fluid forces acting on body segments toward directions perpendicular to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Ftangent: The sum of the fluid forces acting on body segments along the direction parallel to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Faddmass: The sum of the inertial force acting on the body segments due to the acceleration of a mass

© American Physical Society. The authors thank Oliver Morsch for many stimulating discussions and acknowledge support from the Spanish MICINN through Grant Nos. FIS2007-65723 and FIS2010-21372, Acción Integrada HI2008-0163, and the Ramón y Cajal program (CEC)., We examine the dynamics of ultracold atoms held in optical-lattice potentials. By controlling the switching of a periodic driving potential we show how a phase-induced renormalization of the intersite tunneling can be used to produce directed motion and control wave-packet spreading. We further show how this generation of a synthetic gauge potential can be used to split and recombine wave packets, providing an attractive route to implementing quantum computing tasks., Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Competitividad (MINECO), Subprograma de Acciones Integradas (MINECO), Proyecto Ramón y Cajal, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2011 American Physical Society. This work was supported by the Czech Science Foundation (Grant No. 202/09/0084), Czech Ministry of Education (Grant No. MSM 0021620859), Spanish Ministerio de Ciencia e Innovacion and European regional development fund (Grants No. FIS2009-07277, No. FIS2008-04189, No. FIS2009-11621-C02-01, and No. FPA2007-63074), CPAN-Ingenio (Grant No. CSPD-2007-00042-Ingenio 2010), and Junta de Andalucia (Grants No. FQM160, No. FQM318, No. P05FQM437, and No. P07-FQM-02962). The work of P.P.-F. is funded by a FPU grant of the Spanish Ministerio de Educación, and the work of A. R. is funded by the program CPAN Consolider-Ingenio 2010., We study the critical behavior of excited states and its relation to order and chaos in the Jaynes-Cummings and Dicke models of quantum optics. We show that both models exhibit a chain of excited-state quantum phase transitions demarcating the upper edge of the superradiant phase. For the Dicke model, the signatures of criticality in excited states are blurred by the onset of quantum chaos. We show that the emergence of quantum chaos is caused by the precursors of the excited-state quantum phase transition., Czech Science Foundation, Czech Ministry of Education, Spanish Ministerio de Ciencia e Innovacion and European regional development, CPAN-Ingenio, Junta de Andalucía, Spanish Ministerio de Educación, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub