The paper proposes an ultra-narrow band graphene refractive index sensor, consisting of a patterned graphene layer on the top, a dielectric layer of SiO2 in the middle, and a bottom Au layer. The ...absorption sensor achieves the absorption efficiency of 99.41% and 99.22% at 5.664 THz and 8.062 THz, with the absorption bandwidths 0.0171 THz and 0.0152 THz, respectively. Compared with noble metal absorbers, our graphene absorber can achieve tunability by adjusting the Fermi level and relaxation time of the graphene layer with the geometry of the absorber unchanged, which greatly saves the manufacturing cost. The results show that the sensor has the properties of polarization-independence and large-angle insensitivity due to the symmetric structure. In addition, the practical application of testing the content of hemoglobin biomolecules was conducted, the frequency of first resonance mode shows a shift of 0.017 THz, and the second resonance mode has a shift of 0.016 THz, demonstrating the good frequency sensitivity of our sensor. The S (sensitivities) of the sensor were calculated at 875 GHz/RIU and 775 GHz/RIU, and quality factors FOM (Figure of Merit) are 26.51 and 18.90, respectively; and the minimum limit of detection is 0.04. By comparing with previous similar sensors, our sensor has better sensing performance, which can be applied to photon detection in the terahertz band, biochemical sensing, and other fields.
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•High-quality carnation flower-like Bi2O2CO3 hierarchical architectures have been synthesized.•Their photoreduction performance for remoing Cr(VI) was evaluated.•Effects of various ...factors on the photoreduction efficiency and involved mechanism were investigated.•Effects of various parameters on the absorbance of the Cr(VI) solution were investigated.
In this study, we have synthesized high-quality carnation flower-like Bi2O2CO3 hierarchical architectures via a hydrothermal route. The as-synthesized Bi2O2CO3 photocatalyst was systematically characterized and analyzed by various techniques. Its photocatalytic activity was investigated by simulated-sunlight driving photoreduction of Cr(VI), revealing that it exhibits excellent photocatalytic removal of Cr(VI). The effects of various factors (H2SO4, NaOH, Cr(VI) concentration, catalyst dosage) on the photoreduction efficiency and involved mechanism were systematically investigated and discussed. In addition, we have also systematically examined the effects of various parameters (H2SO4 concentration, 1,5-diphenylcarbazide (DPC) concentration, Cr(VI) concentration, reaction time t and reaction temperature T) on the absorbance of the Cr(VI) solution, with the aim of correctly determining the Cr(VI) concentration according to UV–vis absorption measurements using DPC as the chromogenic agent.
Internet public opinion is a complex and changeable system, and its trend development is characterized by explosive, evolutionary uncertainty, concealment and interactivity due to the participation ...of the vast number of Internet users. Today, with the rapid development of network information technology, public opinion has an increasing influence on the stable development of society. Computational intelligence is the frontier field of artificial intelligence development, and computational intelligence is used to mine and analyze public opinion text information and study the evolution of online public opinion. This paper uses the Changchun Changsheng Vaccine Incident as an example, and the netizens’ degree of attention to emergency-related keyword searches in the Baidu Index as a descriptive variable for the development of network public opinion. After applying the optimal segmentation algorithm, the development of public opinion is divided into phases. On this basis, a social network analysis is adopted to analyze the spatial and topological structure of each phase of network public opinion, using data from the Sina Weibo platform. Based on optimal segmentation, the development of network public opinion of the Changchun Changsheng Vaccine Incident can be divided into four phases, namely latent, spreading, control, and stable; each phase has different spatial and topological characteristics. Corresponding policy suggestions on network public opinion governance are put forward for each phase.
As an empirical case, this study takes 30 sudden reversal events as examples, combined with the theory of actor network, and explores the four influencing factors of public opinion subjects-netizens ...and opinion leaders, public opinion objects-events, public opinion carriers-media, and public opinion guides-government in public opinion. The complex combinatorial effects arise during the reversal process. This study verifies the combination of three parallel and equivalent driving paths that lead to the multi-center reversal of public opinion, the opinion leader–media dual-driven path, the opinion leader–media–government multi-driven path, and the media–government dual-driven path. It is concluded that the public should improve their media literacy and maintain a rational return; the media, as “gatekeepers”, need to improve their own awareness and build an objective issue framework; the government needs to establish active communication awareness, and supervision and guidance should go hand in hand.
Highlights
Small cobalt nanoparticles are carefully encapsulated into a N-doped carbon shell (Co-NC) by calcining a Prussian blue analogue precursor.
The presence of cobalt nanoparticles and Co-N ...bonds not only promotes adsorption behavior, but also reduces the diffusion energy barrier, enabling fast diffusion kinetics of K
+
ions.
The good diffusion kinetics and capacitive adsorption behavior of the Co-NC material synergistically contributes to enhanced potassium storage performances.
Potassium-ion batteries (KIBs) have great potential for applications in large-scale energy storage devices. However, the larger radius of K
+
leads to sluggish kinetics and inferior cycling performance, severely restricting its practical applicability. Herein, we propose a rational strategy involving a Prussian blue analogue-derived graphitized carbon anode with fast and durable potassium storage capability, which is constructed by encapsulating cobalt nanoparticles in nitrogen-doped graphitized carbon (Co-NC). Both experimental and theoretical results show that N-doping effectively promotes the uniform dispersion of cobalt nanoparticles in the carbon matrix through Co–N bonds. Moreover, the cobalt nanoparticles and strong Co–N bonds synergistically form a three-dimensional conductive network, increase the number of adsorption sites, and reduce the diffusion energy barrier, thereby facilitating the adsorption and the diffusion kinetics. These multiple effects lead to enhanced reversible capacities of 305 and 208.6 mAh g
−1
after 100 and 300 cycles at 0.05 and 0.1 A g
−1
, respectively, demonstrating the applicability of the Co-NC anode for KIBs.
In this paper, we consider a collaborative sensing scenario where sensing nodes are powered by energy harvested from the ambient environment. In each time slot, an active sensor consumes one unit ...amount of energy to take an observation and transmit it back to a fusion center (FC). After receiving observations from all of the active sensors in a time slot, the FC aims to extract information from them. We assume that the sensing utility generated by the observations is a concave function of the number of the active sensing nodes in that slot. Our objective is to develop a sensing scheduling policy so that the time average utility generated by the sensors is maximized. We first consider an offline setting, where the energy harvesting profile over duration 0,T-1 for each sensor is known beforehand. Assuming infinite battery capacity at sensors, we show that the optimal scheduling structure has a "majorization" property, and propose a procedure to construct a collaborative sensing policy with the identified structure explicitly. We then consider an online setting, under which the energy harvesting profile is available causally. Assuming the energy harvesting processes at individual sensors are independent but not necessarily identical Bernoulli processes, we show that the expected long-term time average sensing utility has an upper bound under any feasible scheduling policy satisfying the energy causality constraints. We then propose a randomized myopic policy, which aims to select a number of sensors with the highest energy levels to perform the sensing task in each slot. We show that the time average utility generated under the proposed policy converges to the upper bound almost surely as time T approaches infinity, thus it is optimal. The corresponding convergence rate is also explicitly characterized.
In this paper, we study the optimal sensing scheduling problem for an energy harvesting sensor. The objective is to strategically select the sensing time such that the long-term time-average sensing ...performance is optimized. In the sensing system, it is assumed that the sensing performance depends on the time durations between two consecutive sensing epochs. Example applications include reconstructing a wide-sense stationary random process by using discrete-time samples collected by a sensor. We consider both scenarios where the battery size is infinite and finite, assuming the energy harvesting process is a Poisson random process. We first study the infinite battery case and identify a performance limit on the long-term time average sensing performance of the system. Motivated by the structure of the performance limit, we propose a best-effort uniform sensing policy, and prove that it achieves the limit asymptotically, thus it is optimal. We then study the finite battery case, and propose an energy-aware adaptive sensing scheduling policy. The policy dynamically chooses the next sensing epoch based on the battery level at the current sensing epoch. We show that as the battery size increases, the sensing performance under the adaptive sensing policy asymptotically converges to the limit achievable by the system with infinite battery, thus it is asymptotically optimal. The convergence rate is also analytically characterized.
Aqueous zinc ion batteries (AZIBs) demonstrate tremendous competitiveness and application prospects because of their abundant resources, low cost, high safety, and environmental friendliness. ...Although the advanced electrochemical energy storage systems based on zinc ion batteries have been greatly developed, many severe problems associated with Zn anode impede its practical application, such as the dendrite formation, hydrogen evolution, corrosion and passivation phenomenon. To address these drawbacks, electrolytes, separators, zinc alloys, interfacial modification and structural design of Zn anode have been employed at present by scientists. Among them, the structural design for zinc anode is relatively mature, which is generally believed to enhance the electroactive surface area of zinc anode, reduce local current density, and promote the uniform distribution of zinc ions on the surface of anode. In order to explore new research directions, it is crucial to systematically summarize the structural design of anode materials. Herein, this review focuses on the challenges in Zn anode, modification strategies and the three-dimensional (3D) structure design of substrate materials for Zn anode including carbon substrate materials, metal substrate materials and other substrate materials. Finally, future directions and perspectives about the Zn anode are presented for developing high-performance AZIBs.
In this review, we systematically summarized the challenges faced by Zn metal anodes of AZIBs including the causes of dendrite growth, hydrogen evolution, corrosion reactions. The three-dimensional (3D) structure design was considered to be an effective method to protect the zinc anode due to the enhanced electroactive surface area of zinc anode, the reduced local current density, and the uniform distribution of zinc ions on the surface of anode. Thus, a comprehensive overview of the 3D structure design is presented in view of substrate materials for Zn anode. Finally, future directions and perspectives about the Zn anode are proposed for developing high-performance dendrite-free AZIBs based on our best knowledge. Display omitted
•The challenges in Zn anode including the causes of dendrite growth, hydrogen evolution, corrosion reactions are reviewed.•The three-dimensional structure design of substrate materials for Zn anode are summarized systematically.•Future directions and perspectives about the Zn anode are proposed for developing high-performance dendrite-free AZIBs.
MC1R plays an important role in the regulation of the formation, transfer, and deposition of melanin in animals and is important for determining coat color. Many studies have reported on single ...nucleotide polymorphisms (SNPs) in the coding sequence of MC1R. However, few studies have investigated the polymorphisms in the 5’-flanking sequence of MC1R. In this study, we sequenced 2000 bp of the 5’-flanking sequence of MC1R in 300 Taihang chickens with brown feathers (MTH) and 300 Taihang chickens with black feathers (HTH). The sequencing results showed that 4 SNPs (MC1R g.18838722 G > C, g.18838624 T > C, g.18838694 G > A, and g.18838624 C > T) were located in the 5’-flanking sequence of MC1R between the MTH and HTH groups. Association analysis showed that there was a significant correlation between the 4 SNPs and feather color in Taihang chickens. The correlation between MC1R g.18838624 T >C and feather color of Taihang chicken was 100%, of which the CC (E1) genotype is MTH and the TT (E2) genotype is HTH. Furthermore, there was a significant correlation between MC1R g.18838624 T > C and egg production at 302 d. E1 (184.14 ± 0.674) was significantly higher than that in E2 (181.75 ± 0.577) (P < 0.05). Luciferase reporter assays were used to detect the transcriptional activity of MC1R with different SNP genotypes. The results showed that the luciferase activity of E2 was significantly higher than that of E1 (P < 0.05). In addition, transcription factor-binding site predictions showed that E2 creates a new binding site for ZEB1. RT‒qPCR results revealed that the expression of MC1R in E2 was significantly lower than that in E1 (P < 0.05), and the expression of ZEB1 in E2 was significantly higher than that in E1 (P < 0.05). Overexpression and shRNA experiments demonstrated that ZEB1 regulates the expression of MC1R in DF1 cells. ZEB1 has a negative regulatory effect on the transcriptional activity of MC1R; it inhibits the expression of MC1R and affects the feather color of Taihang chickens. This study provides new insight into the molecular mechanism of feather color formation and the transcriptional regulation of MC1R in Taihang chickens.
Na0.44MnO2 has received much interest as a potential cathode material for Sodium-ion batteries (SIBs) because of its unique tunnel structure and the ease of Na+ insertion/extraction. Therefore, the ...size and stability of the tunnel structure are critical factors in solving its low-rate performance and cycle stability. Herein, a lattice regulation strategy to enlarge the size in favor of Na+ insertion/extraction and to maintain the stability of the tunnel structure of Na0.44MnO2 by Ti and trace Mg co-doping is reported for the first time. Subsequently, the Na0.44Mn0.895Ti0.1Mg0.005O2 (NMO-TM) material is synthesized with Ti/Mg co-doping. The structure and phase composition of the as-synthesized samples are investigated through X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The results indicate that Ti/Mg has been effectively doped into the crystal structure of Na0.44MnO2 while it maintains the stability of the tunnel structure. The material was used as cathode materials of rechargeable sodium-ion batteries. As a result, at a 1 C rate, the NMO-TM sample exhibits a considerable capacity of 110 mAh g−1, with retention rates of up to 93.6 % after 200 cycles. Even at a higher cycle rate of 20 C, the NMO-TM sample maintains a specific capacity of 80.0 mAh g−1, with a retention rate of 67 % after 2000 cycles. This work provides a facile strategy for regulating the tunnel structure to get stable and high-rate performance of cathode materials.
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•A lattice regulation strategy is used to enlarge the tunnel size and to maintain the stability of the structure of Na0.44MnO2.•The Na0.44Mn0.895Ti0.1Mg0.005O2 has excellent ultra-high rate performance and cycle performance for SIBs cathode material.
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