34 research outputs found
Design and Demonstration of a TDD-Based Central-Coordinated Resource-Reserved Multiple Access (CRMA) Scheme for Bidirectional VLC Networking
The sharply growing demand for increased transmission capacity and bandwidth in last meter and last mile access networks together with the commercialization of fifth generation (5G) wireless systems has been opening up new opportunities for non-radio frequency (RF)-based wireless technologies. Visible light communications (VLC) technology is a potential candidate for access networking in 5G, which offers a higher spectral efficiency than RF-based Femtocell networks by three orders of magnitude. This paper proposes an all wireless optical bidirectional VLC multiple access scheme for pure VLC network access points in terminals. Centralized coordination is adopted to reduce the system complexity. And reservation of resource is introduced to guarantee collision avoidance during data frame transmission. The proposed multiple access scheme introduces special system parameters to achieve the balance of system throughput and access latency. The feasibility of the proposed scheme is verified by both theoretical analysis and experimental investigation. We show that the proposed scheme is suitable for a bidirectional pure VLC access network and can be used as a supplement in the IEEE 802.11 bb for 5G+bidirectional VLC application scenarios
Regulatory Mechanisms of bHLH Transcription Factors in Plant Adaptive Responses to Various Abiotic Stresses
Basic helix-loop-helix proteins (bHLHs) comprise one of the largest families of transcription factors in plants. They have been shown to be involved in responses to various abiotic stresses, such as drought, salinity, chilling, heavy metal toxicity, iron deficiency, and osmotic damages. By specifically binding to cis-elements in the promoter region of stress related genes, bHLHs can regulate their transcriptional expression, thereby regulating the plantâs adaptive responses. This review focuses on the structural characteristics of bHLHs, the regulatory mechanism of how bHLHs are involved transcriptional activation, and the mechanism of how bHLHs regulate the transcription of target genes under various stresses. Finally, as increasing research demonstrates that flavonoids are usually induced under fluctuating environments, the latest research progress and future research prospects are described on the mechanisms of how flavonoid biosynthesis is regulated by bHLHs in the regulation of the plantâs responses to abiotic stresses
Probing the fractional quantum Hall phases in valley-layer locked bilayer MoS
Semiconducting transition-metal dichalcogenides (TMDs) exhibit high mobility,
strong spin-orbit coupling, and large effective masses, which simultaneously
leads to a rich wealth of Landau quantizations and inherently strong electronic
interactions. However, in spite of their extensively explored Landau levels
(LL) structure, probing electron correlations in the fractionally filled LL
regime has not been possible due to the difficulty of reaching the quantum
limit. Here, we report evidence for fractional quantum Hall (FQH) states at
filling fractions 4/5 and 2/5 in the lowest LL of bilayer MoS, manifested
in fractionally quantized transverse conductance plateaus accompanied by
longitudinal resistance minima. We further show that the observed FQH states
sensitively depend on the dielectric and gate screening of the Coulomb
interactions. Our findings establish a new FQH experimental platform which are
a scarce resource: an intrinsic semiconducting high mobility electron gas,
whose electronic interactions in the FQH regime are in principle tunable by
Coulomb-screening engineering, and as such, could be the missing link between
atomically thin graphene and semiconducting quantum wells.Comment: 10 pages, 4 figure
Room temperature 2D ferromagnetism in few-layered 1-CrTe
Spin-related electronics using two dimensional (2D) van der Waals (vdW)
materials as a platform are believed to hold great promise for revolutionizing
the next generation spintronics. Although many emerging new phenomena have been
unravelled in 2D electronic systems with spin long-range orderings, the
scarcely reported room temperature magnetic vdW material has thus far hindered
the related applications. Here, we show that intrinsic ferromagnetically
aligned spin polarization can hold up to 316 K in a metallic phase of
1-CrTe in the few-layer limit. This room temperature 2D long range
spin interaction may be beneficial from an itinerant enhancement. Spin
transport measurements indicate an in-plane room temperature negative
anisotropic magnetoresistance (AMR) in few-layered CrTe, but a sign
change in the AMR at lower temperature, with -0.6 at 300 K and +5 at 10
K, respectively. This behavior may originate from the specific spin polarized
band structure of CrTe. Our findings provide insights into magnetism in
few-layered CrTe, suggesting potential for future room temperature
spintronic applications of such 2D vdW magnets.Comment: 9 Pages, 4 Figure
Mechanical Detection of Magnetic Phase Transition in Suspended CrOCl Heterostructures
With their outstanding mechanical and magnetic characteristics, two-dimensional magnetic materials have attracted wide attentions in the field of nanoelectromechanics and spintronics. By tuning the mechanical resonance with external knobs, such as strain, electric and magnetic control, nanoelectromechanical sensors with novel functionalities have been successfully demonstrated. Here, we investigate the mechanical properties of the suspended membranes with few-layered antiferromagnetic material CrOCl. The results show that the Youngâs modulus of CrOCl resonators is ~137.29 GPa by using a static detection method. Below the transition temperature TN, the mechanical resonance is found to strongly depend on the magnetic fields with an enormous blueshift of ~3.1% in the magnetic-field-induced phase transition. In addition, we also found that the variation of strain of system âÏ” was about 1.5 Ă 10â3 during the transition. Our study shows the great potential of two-dimensional magnetic materials in future nanoelectronic applications
Multimedia Effects in Initial Instruction and Feedback on Problem Solving
While it is well established that multimedia materials presented during instruction often increase learning, prior research has mostly incorporated only text in the feedback. The current experiment tests whether multimedia materials in feedback benefit student learning. We randomly assigned undergraduate students (N = 129) to one of four conditions using a 2 (Main Instruction Modality: text-only vs text-with-diagrams) x 2 (Feedback Modality: text-only vs text-with-diagram) design and tested their learning of conditional probability problems. The results from an immediate posttest suggest that multimedia feedback is more beneficial than text-only feedback, but we did not find any evidence that the modality of the initial instruction influenced learning in this context. Moreover, studentsâ self-ratings of learning suggest a mismatch between their perception of benefits versus actual benefits of the materials. Analyses of studentsâ learning process data - including their practice test performance, time on task, and drawings - suggest that multimedia presentations influence learning differently when presented at initial instruction versus feedback. Diagrams during instruction lead students to put in more explicit effort and to perceive diagrams as helpful, but diagrams during feedback seem to influence learning in a more implicit, reinforcement-learning manner
Modification-Specific Proteomic Analysis Reveals Cysteine SâNitrosylation Mediated the Effect of Preslaughter Transport Stress on Pork Quality Development
This study aimed to explore the effects of preslaughter
transport
stress on protein S-nitrosylation levels and S-nitrosylated proteome
in post-mortem pork longissimus thoracis (LT) muscle.
Pigs (N= 16) were randomly divided into 3 h transport
(high-stress group, HS) and 3 h transport followed by 3 h resting
treatments (low-stress control group, LS). Results demonstrated that
high transport stress levels induced nitric oxide (NO) overproduction
by promoting NO synthase (NOS) activity and neuronal NOS (nNOS) expression,
which thereby notably increased protein S-nitrosylation levels in
post-mortem muscle (p < 0.05). Proteomic analysis
indicated that 133 S-nitrosylation-modified cysteines belonging to
85 proteins were significantly differential, of which 101 cysteines
of 63 proteins were higher in the HS group (p <
0.05). Differential proteins including cytoskeletal and calcium-handling
proteins, glycolytic enzymes, and oxidoreductase were mainly involved
in the regulation of muscle contraction and energy metabolism that
might together mediate meat quality development. Overall, this study
provided direct evidence for changes in S-nitrosylation levels and
proteome in post-mortem muscle in response to preslaughter transport
stress and revealed the potential impact of S-nitrosylated proteins
on meat quality
A Fully Coupled Tribocorrosion Simulation Method for Anchor Chain Considering Mechano-Electrochemical Interaction
This study aims at proposing a fully coupled numerical simulation method of tribocorrosion development on anchor chains during service life, where the mechano-electrochemical interaction is considered in a simplified way. The damage evolution can be realized by a user-defined UMESHMOTION FORTRAN subroutine, where both stress-accelerated corrosion and corrosion-accelerated wear can be considered. Based on this numerical method, the time-variant damage morphology of mooring chain can be obtained. Simulation results obtained by different damage evolution models are shown and compared, and some discussions on the simplified simulation method of reciprocating tribocorrosion are also presented. A systematic parametric study is carried out, and the key factors affecting the tribocorrosion of chain link are revealed. Finally, a modified design method is proposed, and it can be used for optimization of the design of marine anchor chains
Integrated and BinderâFree Air Cathodes of Co 3
All-solid-sate Al-air batteries with features of high theoretical energy density,
low cost, and environmental-friendliness are promising as power sources for
next-generation flexible and wearable electronics. However, the sluggish
oxygen reduction reaction (ORR) and poor interfacial contact in air cathodes
cause unsatisfied performance. Herein, a free-standing Co3Fe7 nanoalloy and
Co5.47N encapsulated in 3D nitrogen-doped carbon foam
([email protected]/NCF) is prepared as an additive-free and integrated air
cathode for flexible Al-air batteries in both alkaline and neutral electrolytes.
The [email protected]/NCF outperforms commercial platinum/carbon (Pt/C)
toward ORR with an onset potential of 1.02 V and a positive half-wave
potential of 0.92 V in an alkaline electrolyte (0.59 V in sodium chloride
solution), which is ascribed to the unique interfacial structure between Co3Fe7
and Co5.47N supported by 3D N-doped carbon foam to facilitate fast electron
and mass transfer. The high ORR performance is also supported by in-situ
electrochemical Raman spectra and density functional theory calculation.
Furthermore, the fabricated Al-air battery displays good flexibility and delivers
a power density of 199.6 mW cmâ2, and the binder-free and integrated
cathode shows better discharge performance than the traditionally slurry
casting cathode. This work demonstrates a facile and efficient approach to
develop integrated air cathode for metal-air batteries