We propose methods for synthesizing multilayer optical lattices of cold atoms in a layer-by-layer manner, to unlock the potential of optical lattices in simulating novel multilayer systems. The ...scheme combines compressed Gaussian beams of far red-detuned laser and an optical device with modified Michelson interferometers as key components. The compressed Gaussian beam makes possible standalone and purely two-dimensional optical lattices, which are the building blocks of target multilayer optical lattices. The modified Michelson interferometers split one compressed Gaussian beam into several beams, in a manner allowing delicate control over the vertical distances between the outgoing beams and their propagation directions. We illustrate the proposal with the displaced dice lattice, which is a trilayer lattice that maps to the dice lattice when projected to the same layer. Both the dice model and its interesting variants may be realized. We also discuss extensions to other interesting multilayer lattices such as the twisted multilayer lattices.
In this paper, three-phase interior permanent magnet brushless DC motors are analyzed. The effect of magnetization direction, number of stator slots, winding distribution, skew angle, current ...waveform, and advance angle on torque pulsation is examined. Finite element method is used to calculate the torque, reluctance torque, back iron flux density, tooth flux density, detent torque, and back electromotive force of the motors. Switching instants are calculated such that the reluctance torque can be utilized and maximum torque with reduced pulsation is achieved. Experimental results to support the simulation findings are included in this paper.
Diet and dietary components have profound effects on the composition of the gut microbiota and are among the most important contributors to the alteration in bacterial flora. This review examines the ...effects the "Western", "plant-based", "high-fat", "medical ketogenic", and "Mediterranean" diets have on the composition of the gut microbiota in both mice and human subjects. We show that specific dietary components that are commonly found in the "plant-based" and "Mediterranean" diet play a role in shifting the microbial composition. This review further evaluates the bacterial metabolites that are associated with diet, and their role in systemic inflammation and metabolic endotoxemia. Furthermore, the associations between diet/dietary components and altering bacterial composition, may lead to potential therapeutic targets for type II diabetes, obesity, and inflammatory diseases.
We analyze the energy spectra of Dirac fermions in the presence of rotation and magnetic field. We find that the Landau degeneracy is resolved by rotation. A drastic change in the energy dispersion ...relation leads to the "rotational magnetic inhibition" that is a novel phenomenon analogous to the inverse magnetic catalysis in a magnetic system at finite chemical potential.
Advances in self-powered triboelectric pressure sensors Lei, Hao; Chen, Yunfeng; Gao, Zhenqiu ...
Journal of materials chemistry. A, Materials for energy and sustainability,
09/2021, Letnik:
9, Številka:
36
Journal Article
Recenzirano
Pressure sensors have attracted much attention for their potential applications in health monitoring, wearable devices, electronic skins, smart robots,
etc
. With the rapid development of the ...Internet of Things, considering the large number and small scale of sensors, power consumption has become a key factor in large-scale applications. A new generation of self-powered pressure sensors based on a triboelectric nanogenerator has been developed in terms of its incomparable advantages in power consumption and potential performance. Based on the coupling effects of triboelectrification and electrostatic induction, it enables obtaining information on the mechanical input,
e.g.
, magnitude and frequency, by analyzing the electrical output signals. Intensive efforts have been devoted to improving the sensing performance of triboelectric pressure sensors to meet the demands of practicality. In this review, the key advancements in materials, structures and applications of self-powered triboelectric pressure sensors are systematically reviewed. Then, the theoretical basis, impact mechanism and approaches to optimize the pressure sensing performance have been comprehensively analyzed. Finally, the future perspectives of self-powered triboelectric pressure sensors have also been discussed.
Triboelectric pressure sensors arouse great interest in wearable electronics due to their self-powered property. Here, recent key advancements of triboelectric pressure sensors are comprehensively reviewed and some future trends are also discussed.
Most scholars have argued that student engagement positively predicts academic achievement, but some have challenged this view. We sought to resolve this debate by offering conclusive evidence ...through a meta-analysis of 69 independent studies (196,473 participants). The results revealed
that (a) there was a moderately strong and positive correlation between overall student engagement and academic achievement, and an analysis of the domains of behavioral, emotional, and cognitive engagement showed that almost all had a positive correlation with students' academic achievement;
and (b) a moderator analysis revealed that the relationship between student engagement and academic achievement was influenced by the method of reporting engagement, cultural value, and gender. Furthermore, the relationships of behavioral, emotional, and cognitive engagement with academic
achievement were influenced by reporting method for engagement, cultural value, or gender.
Celotno besedilo
Dostopno za:
DOBA, FSPLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This meta-analysis examines the association between teacher support and students' academic emotions both positive academic emotions (PAEs) and negative academic emotions (NAEs) and explores how ...student characteristics moderate these relationships. We identified 65 primary studies with 58,368 students. The results provided strong evidence linking teacher support and students' academic emotions. Furthermore, students' culture, age, and gender moderated these links. The correlation between teacher support and PAEs was stronger for Western European and American students than for East Asian students, while the correlation between teacher support and NAEs was stronger for East Asian students than for Western European and American students. Also, the correlation between teacher support and PAEs was strong among university students and weaker among middle school students, compared to other students. The correlation between teacher support and NAEs was stronger for middle school students and for female students, compared to other students.
Abundant and ubiquitous thermal heat called low-grade heat (<150 °C) is wasted in our surroundings owing to the lack of effective and low-cost energy technologies. Thermo-electrochemical cells ...(TECs), mainly containing thermogalvanic cells and thermally charged capacitors, are one of the most promising candidates for heat to electricity conversion. They have been intensively investigated owing to the giant thermopower, intrinsic flexibility, low cost and good scalability. To date, great progress such as the giant thermopower (−37 mV K
−1
), large figure-of-merit (3.74) and high efficiency (11.1%) has been made for TECs. In addition, some functionalized TECs including flexible, stretchable, self-healable and antifreeze TECs have also been developed. However, it is still a great challenge to develop such TECs that combine high power density and efficiency as well as multifunction abilities for practical applications, particularly the thermogalvanic cells (which can continuously output electricity). Herein, we comprehensively summarized TECs from foundations to materials, strategies to engineering designs and opportunities to challenges, expecting to promote the development of TECs toward more superior performance and practicability.
Thermo-electrochemical cells, a promising heat to electricity conversion technology, which originates from thermogalvanic effect or/and Soret effect.
In this letter, we demonstrated an all-silica fiber 1.5-3.2 μm supercontinuum (SC) source based on germanium-doped highly nonlinear fibers (HNLF). By optimizing the length of HNLF, as the pump ...injected into the HNLF increased to 6 W, a 4.12 W broadband SC source extending from 1516 to 3182 nm was obtained. The 3 dB spectrum bandwidth was up to 1022 nm ranging from 1855 nm to 2877 nm, and the 1 dB bandwidth was up to 878 nm covering from 1959 nm to 2837 nm. To the best of our knowledge, this is the flattest SC in the 2-3 μm region based on doped silica fiber to date.
Noble metal catalysts are still the best methanol oxidation reaction (MOR) catalysts for direct methanol fuel cells nowadays, because the MOR onset potential of non-noble metal-based catalysts is ...much higher than that of Pt (usually greater than 1.35 V
vs.
RHE), so that the potential of the MOR is even higher than that of the oxygen reduction reaction and cannot form a cell. Here, we develop a high-performance non-noble-metal based (CoSn) MOR catalyst with a small amount (3.2 wt%) of Pt, which exhibits overpotential even lower than that of Pt/C (260 mV lower), unparalleled stability (retains 610 mA mg
Pt
−1
after chronoamperometry testing for 28 h, the best value for methanol oxidation reported to date) and high methanol oxidation activity (3680 mA mg
Pt
−1
). We synthesize this CoSn-Pt catalyst by innovatively utilizing a Pt plate as a counter electrode (which is always avoided to prevent potential pollution of Pt in the past) to realize composite electrodeposition in a deep eutectic solvent.
We innovatively develop a high-performance MOR catalyst with small amounts (3.2 wt%) of Pt by composite electrodeposition using a Pt plate as a counter electrode. The material exhibits ultra-high voltage efficiency and unparalleled stability.
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