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This paper describes the use of a highly crystalline conductive 2D copper3(hexaiminobenzene)2 (Cu3(HIB)2) as an ultrasensitive (limit of detection of 1.8 part‐per‐billion), highly selective, reversible, and low power chemiresistive sensor for nitric oxide (NO) at room temperature. The Cu3(HIB)2‐based sensors retain their sensing performance in the presence of humidity, and exhibit strong signal enhancement towards NO over other highly toxic reactive gases, such as NO2, H2S, SO2, NH3, CO, as well as CO2. Mechanistic investigations of the Cu3(HIB)2‐NO interaction through spectroscopic analyses and density functional theory revealed that the Cu‐bis(iminobenzosemiquinoid) moieties serve as the binding sites for NO sensing, while the Ni‐bis(iminobenzosemiquinoid) MOF analog shows no noticeable response to NO. Overall, these findings provide a significant advance in the development of crystalline metal‐bis(iminobenzosemiquinoid)‐based conductive 2D MOFs as highly sensitive, selective, and reversible sensing materials for the low‐power detection of toxic gases. [ABSTRACT FROM AUTHOR]

Carbon nanofillers in general and graphene in particular are considered as promising potential candidates in catalysis due to their two‐dimensional (2D) nature, zero bandwidth, single atom thickness with a promising high surface area: volume ratio. Additionally, graphene oxide via result of tunable electrical properties has also been developed as a catalytic support for metal and metal oxide nanofillers. Moreover, the possession of higher chemical stability followed by ultrahigh thermal conductivity plays a prominent role in promoting higher reinforcement of catalytically active sites. In this review we have started with an overview of carbon nanofillers as catalyst support, their main characteristics and applications for their use in heterogeneous catalysis. The review article also critically focusses on the catalytic properties originating from both functional groups as well as doping. An in‐depth literature on the various reaction catalysed by metal oxide based nanoparticles supported on GO/rGO has also been incorporated with a special focus on the overall catalytic efficiency with respect to graphene contribution. The future research prospective in the aforementioned field has also been discussed. [ABSTRACT FROM AUTHOR]

Direct formic acid fuel cells have attracted significant attention due to their low fuel crossover, high safety, and high theoretical power density among all proton‐exchange membrane fuel cells. Numerous efforts have been dedicated to studying formic acid oxidation, particularly in the fabrication of high‐performance electrocatalysts with economical utilization of Pt metal. In this work, we report a synthetic strategy to create PtAg dots supported on plate‐like Au nanoparticles and explore their applications in electrocatalytic formic acid oxidation. The highly dispersed nature of the catalytic Pt centers and the successful construction of PtAg−Au trimetallic interfaces makes the current nanostructure an ideal system to allow for a synergetic effect between Pt, Au, and Ag, leading to improved electrocatalysis. Compared with commercial Pt/C, our PtAg‐on‐Au heterogenous nanoplates exhibit superior mass activity, along with enhanced reaction kinetics and long‐term durability for FAOR in an acidic medium. Density functional theory (DFT) simulation results indicate that AgPtAu(111) exhibits a relatively high activity for HCOOH oxidation into CO2 among the various Au‐based catalysts. This work provides a viable strategy for constructing Pt‐based electrocatalysts with controlled Pt ensembles, offering insights into the development of fuel cell catalysts that make highly efficient use of costly noble metals. [ABSTRACT FROM AUTHOR]

Coordination polymers (CPs) have received a lot of attention as lithium-ion battery (LIB) anode electrode materials because of their varied chemical structure. In this paper, a novel two-dimensional (2D) [Co(BDC)1/2(PZA)(H2O)2]n (Co-CP) as anode material for rechargeable LIBs is introduced to meet the challenges of poor cycling performance and low specific capacity of organic electrode materials by a simple hydrothermal reaction. The Co-CP delivered high electrolyte stability due to the combination of the metal center and the organic ligand, and it has a significant reversible capacity of 843 mAh g−1 at 200 mA g−1 after 200 cycles when tested as LIB anode materials. The electrode was able to regain its initial capabilities when the current rate was reduced to 100 mA g−1 after elevating at the high current density test of 2000 mA g−1, suggesting the good rate performance of Co-CP. The experimental results show that the synergistic redox reaction of the metal center and the organic ligand contributes to the high lithium storage performance. [ABSTRACT FROM AUTHOR]

Ultrasound‐based elastography techniques are increasingly available on modern ultrasound systems. The application of elastography extends the utility of ultrasound, yielding new information about the impact of disease on tissue biomechanics. By modifying the B‐mode imaging pulse, an Acoustic Radiation Force Impulse produces shear waves in selected tissue. Quantifying the speed of the resultant shear wave provides an indirect assessment of tissue stiffness, with stiffer tissue producing faster shear wave movement than softer tissue. Two main types of ultrasound shear wave elastography are currently in use. Point shear wave elastography uses one or two pulses to measure shear wave speeds over a small fixed area. Alternatively, two‐dimensional shear‐wave elastography provides a colour elastogram map over a larger area, allowing the operator to select specific regions of interest to measure shear wave speed. This article will discuss the essential physics principles, and clinical uses of two‐dimensional shear wave elastography, aiming to provide sonographers with a basic understanding of the technology and current applications. [ABSTRACT FROM AUTHOR]

The growing understanding of the role of extracellular vesicles (EVs) in embryo)maternal communication has sparked considerable interest in their therapeutic potential within assisted reproductive technology, particularly in enhancing implantation success. However, the major obstacle remains the large-scale production of EVs, and there is still a gap in understanding how different culture systems affect the characteristics of the EVs. In the current study, trophoblast analogue human chorionic carcinoma cell line was cultivated in both conventional monolayer culture (2D) and as spheroids in suspension culture (3D) and how the cell growth environment affects the physical, biochemical and cellular signalling properties of EVs produced by them was studied. Interestingly, the 3D system was more active in secreting EVs compared to the 2D system, while no significant differences were observed in terms of morphology, size, and classical EV protein marker expression between EVs derived from the two culture systems. There were substantial differences in the proteomic cargo profile and cellular signalling potency of EVs derived from the two culture systems. Notably, 2D EVs were more potent in inducing a cellular response in endometrial epithelial cells (EECs) compared to 3D EVs. Therefore, it is essential to recognize that the biological activity of EVs depends not only on the cell of origin but also on the cellular microenvironment of the parent cell. In conclusion, caution is warranted when selecting an EV production platform, especially for assessing the functional and therapeutic potential of EVs through in vitro studies. [ABSTRACT FROM AUTHOR]

Cobalt telluride, with tunable magnetism and ferromagnetism that hinged upon the stoichiometric ratio, has emerged as a new member of 2D materials in the last decade. Metallic doping by sodium (Na) and platinum (Pt) atoms below critical concentrations is found to enhance the magnetism of cobalt telluride. After thinning cobalt telluride down to few‐layer, the saturation magnetism is improved by two order of magnitudes because of the oxidation state of cobalt (Co) and reduced coordination number of the surface atoms. In 2D limit, cobalt di‐telluride possesses Dirac band structure with many nodal lines that correlate with quantum criticality and other fantastic physics. In this mini‐review, the crystal and band structures of cobalt telluride categorized by stoichiometric ratio are overviewed after briefing the introduction. Both top‐down and bottom‐up methods are then discussed to offer optimum solutions for each specified application scenario. Afterward, emerging magnetic and electronic properties and credit enhancements are launched accompanied with their key advances. Beyond these, the faced challenges and possible directions of future research are also provided, attempting to boost both fundamental physics and device applications based on 2D cobalt telluride. [ABSTRACT FROM AUTHOR]

The growing understanding of the role of extracellular vesicles (EVs) in embryo-maternal communication has sparked considerable interest in their therapeutic potential within assisted reproductive technology, particularly in enhancing implantation success. However, the major obstacle remains the large-scale production of EVs, and there is still a gap in understanding how different culture systems affect the characteristics of the EVs. In the current study, trophoblast analogue human chorionic carcinoma cell line was cultivated in both conventional monolayer culture (2D) and as spheroids in suspension culture (3D) and how the cell growth environment affects the physical, biochemical and cellular signalling properties of EVs produced by them was studied. Interestingly, the 3D system was more active in secreting EVs compared to the 2D system, while no significant differences were observed in terms of morphology, size, and classical EV protein marker expression between EVs derived from the two culture systems. There were substantial differences in the proteomic cargo profile and cellular signalling potency of EVs derived from the two culture systems. Notably, 2D EVs were more potent in inducing a cellular response in endometrial epithelial cells (EECs) compared to 3D EVs. Therefore, it is essential to recognize that the biological activity of EVs depends not only on the cell of origin but also on the cellular microenvironment of the parent cell. In conclusion, caution is warranted when selecting an EV production platform, especially for assessing the functional and therapeutic potential of EVs through in vitro studies.

Traditional fault diagnosis methods have disadvantages such as incomplete coding and overly absolute coding boundaries, which are difficult to meet the actual needs of power grid operation and maintenance. Using the gas generated when a power transformer fails to diagnose the transformer fault is currently a popular research area for smart grid condition detection. However, the frequency of various types of faults in transformers varies greatly, which may result in incomplete fault sample information and insufficient data, and the traditional convolutional neural net- work models have problems such as unstable training process, low training accuracy and long time. Based on the transformer fault diagnosis technology of one dimensional convolutional neural network, this study proposes a new method of data enhancement while keeping the original data features unchanged, transforming expanded one dimensional data into two dimensional pictures to input into the two dimensional convolutional neural network diagnosis model, and improve the Adam optimization algorithm in the convolutional neural network model architecture. Diagnostic results indicate that the accuracy of network training reaches 96. 20%. At the same time, it has higher convergence speed and generalization ability than the traditional one dimensional convolutional neural network fault diagnosis method (92.12%). [ABSTRACT FROM AUTHOR]

Cutting and packing problems have been widely studied in the last decades, mainly due to the variety of industrial applications where the problems emerge. This paper presents an overview of the solution approaches that have been proposed for solving two‐dimensional rectangular cutting and packing problems. The main emphasis of this work is on two distinct problems that belong to the cutting and packing problem family. The first problem aims to place onto an object the maximum‐profit subset of items, that is, output maximization, while the second one aims to place all the items using as few identical objects as possible, that is, input minimization. The objective of this paper is not to be exhaustive but to provide a solid grasp on two‐dimensional rectangular cutting and packing problems by describing their most important solution approaches. [ABSTRACT FROM AUTHOR]

2D half‐metallic multiferroic materials have attracted great interest due to their rich novel performances and wide application prospect in nanoelectronics and nanodevices. Three intrinsic half‐metallic multiferroic monolayers AV2S4 (A = Na, K, and Rb) are predicted based on the first‐principles calculations. From the calculations, their ground states are all ferromagnetic and are completely spin‐polarized at the Fermi level. Their total magnetic moments are always 3.00 μB per primitive cell, which origin mainly from V‐ions. The two‐center electronic structure t2g6↑t2g4↓eg1↑ of V‐ions is proposed from the perspective of the crystal field theory to explain successfully the calculated magnetic moments. Interestingly, the alkali‐metal ions are non‐magnetic, but they may cause important influence on the magnetic coupling between transition ions, and then the half‐metallicity of these monolayers. Their electric and magnetic properties may be tuned by their charge states and strains. Especially, their half‐metallic stability may be evidently improved by the tensile strains. The half‐metallic gaps of these monolayers may be increased by about 67.4%, 50.8%, and 32.4% for NaV2S4, KV2S4, and RbV2S4 by the tensile strain 2.0%, respectively. [ABSTRACT FROM AUTHOR]

2D half‐metallic multiferroic materials have attracted great interest due to their rich novel performances and wide application prospect in nanoelectronics and nanodevices. Three intrinsic half‐metallic multiferroic monolayers AV2S4 (A = Na, K, and Rb) are predicted based on the first‐principles calculations. From the calculations, their ground states are all ferromagnetic and are completely spin‐polarized at the Fermi level. Their total magnetic moments are always 3.00 μB per primitive cell, which origin mainly from V‐ions. The two‐center electronic structure t2g6↑t2g4↓eg1↑ of V‐ions is proposed from the perspective of the crystal field theory to explain successfully the calculated magnetic moments. Interestingly, the alkali‐metal ions are non‐magnetic, but they may cause important influence on the magnetic coupling between transition ions, and then the half‐metallicity of these monolayers. Their electric and magnetic properties may be tuned by their charge states and strains. Especially, their half‐metallic stability may be evidently improved by the tensile strains. The half‐metallic gaps of these monolayers may be increased by about 67.4%, 50.8%, and 32.4% for NaV2S4, KV2S4, and RbV2S4 by the tensile strain 2.0%, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the first order perturbation theory (PT) and the small slope approximation (SSA) are employed to analyze the scattering behavior of a two dimensional dielectric-topological insulator (TI) rough interface with Gaussian distribution. Zeroth and first order scattering amplitudes are utilized to obtain the analytic expressions for the coherent and incoherent intensities, respectively. For vertical incidence, an equation can be found whose numerical solution gives the Brewster angle at which the co polarized coherent intensity becomes zero. The scattering scenarios are analyzed where both polarization states of the incident field exhibit total depolarization and the co polarized incoherent scattering is zero.

This article presents the design of a low-profile, two-dimensional and beam-switching transmitarray antenna for millimetre-wave (26.3-29.3 GHz) applications. The transmitarray panel is designed using two substrate layer polarization rotating phase shift elements. The phase distribution on the transmitarray panel is approximated by 0 and $\pi $ . The phase shift element dimensions are $0.22\lambda _{0}$ x $0.22\lambda _{0}$ x $0.14\lambda _{0}$ , ( $\lambda _{0}$ corresponds to frequency of 28 GHz). The overall size of the transmitarray panel is $5.6~\lambda _{0}$ x $5.6~\lambda _{0}$ with a focus-to-dimension (f/d) ratio of 0.5, which makes the design compact. The panel is fed by a 9-port Yagi array antenna arranged in a $3\times $ 3 configuration. The offset antennas undergo a scanning loss of 1.6 dB with a peak gain of 19.7 dBi in the main beam. The 3-dB beamwidth of 9.8-11.2° is obtained in different radiation beams. The radiation patterns of the offset antennas are tilted ± 15° with respect to the focal antenna, thus giving a radiation coverage of 30°. The antenna can be used in millimetre wave base stations for beam-switching and can also act as a repeater antenna at millimetre wave frequencies in public transport vehicles.

In this paper, the first order perturbation theory (PT) and the small slope approximation (SSA) are employed to analyze the scattering behavior of a two dimensional dielectric-topological insulator (TI) rough interface with Gaussian distribution. Zeroth and first order scattering amplitudes are utilized to obtain the analytic expressions for the coherent and incoherent intensities, respectively. For vertical incidence, an equation can be found whose numerical solution gives the Brewster angle at which the co polarized coherent intensity becomes zero. The scattering scenarios are analyzed where both polarization states of the incident field exhibit total depolarization and the co polarized incoherent scattering is zero. [ABSTRACT FROM AUTHOR]

The excessively leached metal ions from traditional metallic antimicrobial nanoparticles are harmful to biological and human tissues. Metal-organic frameworks (MOFs) coordinating bioactive metal ions to organic bridging ligands can potentially address this issue, avoiding the excessive leaching of metal ions and simultaneously exhibiting high effective antibacterial activities. Here, we report the preparation of a 2-dimensional leaves-like zeolitic imidazolate framework (ZIF-L) for potential antibacterial and anti-algae applications. The ZIF-L nanosheet exhibits complete inactivation of Escherichia coli (phosphate buffer saline: 4 h) and Bacillus subtilis (seawater: 0.5 h). The ZIF-L/epoxy composite has excellent antibacterial effect, poisoning effect and anti-adhesion effect on a variety of marine algae. It is worth noting that the removal rate (Escherichia coli) for ZIF/epoxy composite can be reached to 90.20% by only adding ZIF-L (0.25 wt%). This work will inspire researchers to develop more metal-organic frameworks materials for applications in the antibacterial and anti-algae fields. [ABSTRACT FROM AUTHOR]

We study the abilities of pore network models of different complexities to determine the flow statistics and structural controls for single-phase flow in partially saturated porous media. The medium permeability and hydraulic tortuosity are the basic parameters for upscaling flow problems from the pore to the Darcy scale. They represent average flow properties. However, upscaling and predicting dispersion and anomalous solute transport from the pore to the continuum scale requires knowledge of the velocity distribution, not only its mean values. Considering four different network models of increasing complexity, we analyze the statistical and structural properties of the fluid-filled pore space that determines the flow statistics. We consider statistical network models based on regular lattices with the same statistical properties as the porous medium regarding coordination number and pore-size distribution. We consider regular lattices which are characterized by uniform coordination, and diluted lattices, and random lattices, which are characterized by a distribution of coordination numbers. Furthermore, we consider a detailed network model, which accounts for the spatial location of pores, their coordination numbers, and the sizes of pore bodies and throats. The flow behaviors estimated from these network models are compared to direct numerical single-phase flow simulations in the digitized images of a fully and partially saturated two-dimensional porous medium and different saturation degrees. We find that the statistical network models can capture the saturation dependence of permeability and tortuosity but are not able to reproduce velocity statistics of even the velocity range observed in the direct flow simulations. The detailed network models, in contrast, provide excellent estimates for all flow statistics. This indicates that the configuration and correlation of the fluid phase are crucial structural controls of the observed distribution of flow velocities. Plain Language Summary Conceptualizing a porous media as a network of conductors sets a compromise between the oversimplifying conceptualization of the media as a bundle of capillary tubes and the computationally expensive and unobtainable detailed description of the media's geometry needed for direct numerical simulations. These models are abundantly being used to evaluate single and multiphase flow characteristics. The different flow characteristics are valuable in evaluating phenomena that may or may not be relevant for different applications. Here, we evaluate how different information about the pore space affects the ability of the network model to evaluate different flow characteristics. We found that the resistance of a media to the fluid flow can be estimated by the general stochastic features of the media (its size and connectivity). However, to account for more complex phenomena, such as solute transport and dispersion through the media, a piece of detailed information about the spatial location of the fluids is needed. • Simple network can evaluate the media permeability but not the flow distribution • Pore velocities and tortuosity are controlled by phase configuration not pore geometry • Network properties to match DNS flow statistics are identified. [ABSTRACT FROM AUTHOR]

The present numerical study addresses the buoyancy assisted transient two-dimensional early-stage heat transfer and melting process of PCM's in a square enclosure. Two PCM materials are used namely pure paraffin wax and paraffin with 1 mass % fraction of SiC nano particles. The square enclosure walls are subjected to a constant temperature of 65 °C (Hot wall) and 27 °C (Cold wall) at bottom and top side, respectively, while remaining sides of the enclosure are perfectly insulated. A finite volume (FVM)-based Ansys fluent software along with enthalpy-porosity method is used to capture the phase change process from solid to liquid. The pressure–velocity coupling is performed by coupled scheme, while pressure correction is done by PRESTO method. The transient variation of PCM liquid fraction, temperature, velocity and enthalpy are plotted. The results obtained shows that a notable difference is confined between early melting stages of both paraffin and nano-enhanced paraffin materials. The close observation of velocity vectors clearly shows that the addition of SiC nanoparticles in pure paraffin improves the convective heat transfer rate with time. The addition of SiC nano particles in paraffin reduces the melting time of paraffin but contrary influence the uniformity in temperature distribution and heat transfer characteristics. The presence of SiC nanoparticles increases the liquid fraction and temperature rise by 33% as compared with pure paraffin. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen generation from direct water splitting is recognized as a progressive and renewable energy producer. The secret to understanding this phenomenon is discovering an efficient photocatalyst that preferably uses sunlight energy. Two-dimensional (2D) graphitic carbon nitride (g-C3N4)-based materials are promising for photocatalytic water splitting due to special characteristics such as appropriate band gap, visible light active, ultra-high specific surface area, and abundantly exposed active sites. However, the inadequate photocatalytic activity of pure 2D layered g-C3N4-based materials is a massive challenge due to the quick recombination between photogenerated holes and electrons. Creating 2D heterogeneous photocatalysts is a cost-effective strategy for clean and renewable hydrogen production on a larger scale. The 2D g-C3N4-based heterostructure with the combined merits of each 2D component, which facilitate the rapid charge separation through the heterojunction effect on photocatalyst, has been evidenced to be very effective in enhancing the photocatalytic performance. To further improve the photocatalytic efficiency, the development of novel 2D g-C3N4-based heterostructure photocatalysts is critical. This mini-review covers the fundamental concepts, recent advancements, and applications in photocatalytic hydrogen production. Furthermore, the challenges and perspectives on 2D g-C3N4-based heterostructure photocatalysts demonstrate the future direction toward sustainability.

A series of hexagonal group IV-V (IV=C, Si, Ge, V=N, P, As) phase-α and -β monolayers are studied using the first-principle calculation. The 18 monolayers are all optical transparent semiconductors with band gaps in the range of 1.91–6.06 eV and have good light adsorption in UV range. And each monolayer has its own unique properties. The CN phase-α and -β monolayers have good mechanical properties (large 2D Young's moduli, 555.3 N m−1 and 585.5 N m−1) comparable to that of two layer graphene. The CP-β monolayer is the only one with direct band gap and can translate into indirect semiconductor when applied biaxial tensile strain greater than 4 %, while the CP-α, CAs-α and CAs-β monolayers can realize the transition from the indirect semiconductor to direct one with 6–10 % biaxial tensile strain. The SiN and GeN monolayers are ductile with large Poisson's ratio (∼0.30). And the GeN monolayers can maintain indirect band gaps under 10 % strain and have linear relationships between the band gaps and strains. The GeAs monolayers have partial light adsorption in visible range (several 104 cm−1 in 390–450 nm) and possess water-splitting photocatalytic properties under suitable conditions (neutral and alkaline for the GeAS-α and alkaline for GeAS-β). The different properties of each hexagonal group IV-V (IV=C, Si, Ge, V=N, P, As) binary monolayers can be potential applied in different two dimensional electronic devices. [ABSTRACT FROM AUTHOR]

Introduction: Lateral cephalograms are widely used in Orthodontics as a vital tool for treatment planning in orthodontics. The reliability of cephalometric analyses depends on projection and identification errors. Aim: Comparative assessment of reliability and identification of Craniofacial landmarks on CBCT-synthesised cephalograms vs conventional cephalograms, and to check whether the technique used to synthesize CBCT cephalograms has an impact on the reproducibility of the cephalometric measurements. Materials and Methods: This was a Cross sectional retrospective study was conducted in the Department of Orthodontics and Dentofacial Orthodontics, Guru Nanak Institute of Dental Sciences and Research for six months period of time, where 50 (25 Cone beam computed tomography generated cephalograms and 25 Conventional digital cephalograms) were selected and parameters were studied using Steiners analysis. Seven Linear and nine angular measurements were done. The linear and angular measurement required for different analysis were determined for cephalometric analysis software named Nemoceph (updated version 7). Results: The values of the two imaging modalities does not show any statistically significant difference. Correlation coefficient/r-value shows that both Digital cephalograms and CBCT cephalograms are highly reliable. Conclusion: So, the authors can conclude that both conventional digital lateral cephalogram and CBCT generated cephalogram can be readily used for craniofacial landmarks identification. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) hybrid perovskites with novel functionalities and structural diversity are a perfect platform for emerging optoelectronic devices such as photodetectors, light‐emitting diodes, and solar cells. Here, we demonstrate that excess concentration of Cesium bromide (CsBr) is key to the formation of easily exfoliated 2D Cs2Cu(Cl/Br)4 perovskite crystal. Furthermore, by employing this trick to 2D perovskite MA2Cu(Cl/Br)4 (MA=methylammonium), we achieve a phase‐pure easily exfoliated 2D mixed‐cation (MA/Cs)2Cu(Cl/Br)4 perovskite crystal, which exhibits reduced bandgap (1.53 eV) with ferromagnetic behavior and photovoltaic property. The resultant mixed‐cation structured device reveals enhanced efficiency compared to all MA and all Cs counterparts. These findings demonstrate the importance of cation‐engineering in developing innovative materials with novel properties. [ABSTRACT FROM AUTHOR]

Ti, Cr, Zr and Hf embedded novel C 6 N 3 containing sp-N exhibit excellent performance toward hydrogen evolution. [Display omitted] Two-dimensional (2D) carbon nitrides (C x N y) have great potential in advanced fields such as energy harvest and storage. We report a novel 2D C x N y , C 6 N 3 , comprising sp-N and sp2-C atoms. Density functional theory calculations indicate that electronically, thermally, and dynamically stable C 6 N 3 is metallic even when cut into very narrow nanoribbons. C 6 N 3 adsorbed single atoms of 3d, 4d, and 5d transition metals to fabricate single-atom catalysts (SACs) for an electrocatalytic hydrogen evolution reaction (HER). Among all SACs studied, Ti-, Cr-, Zr-, and Hf-embedded C 6 N 3 had excellent overall performance including promising stability, moderate binding strength of H and H 2 , and good electrical conductivity. Our results suggest a novel C 6 N 3 with an sp-N skeleton that has great potential for HER. More investigations are needed to further understand the properties and applications of C 6 N 3 in other fields. [ABSTRACT FROM AUTHOR]

The production of electricity is important, suitable and secure for human living, yet electricity is actually generated mainly from fossil fuels and nuclear energy, calling for renewable energies such as solar, wind and tidal renewable energies such as solar, wind and tidal. Solar energy is broadly harvested by various types of solar cells. Three-dimensional perovskite solar cell exhibits high power conversion efficiency of 25.2% with low stability, whereas two-dimensional perovskite solar cell exhibits better stability with moderate power conversion efficiency. Hence, we review two-dimensional perovskite solar cells fabricated with varying numbers of hybrid two-dimensional perovskite layers, organic cations, deposition techniques, the addition of additives and capping layers to improve power conversion efficiency with long-term better stability. [ABSTRACT FROM AUTHOR]

In an incoherent optical code division multiple access (OCDMA) system using amplitude spectral coding (SAC), which exceeds 1.5 Gbps, it is difficult or impossible to make a transmission with a bit error rate better than 10–9. For this, it is necessary to associate an error correction code (ECC) to the SAC-OCDMA system. In this paper, we proposed an architecture of a two-dimensional SAC-OCDMA system (spectral (w) and spatial (s)) using multi-diagonal code (MD) as spreading code and low-density parity check code (LDPC) as ECC. According to the properties of the MD code and the proposed architecture, the phase induced intensity noise is eliminated, which has improved the performance of the system. The theoretically results shows that LDPC/2D-SAC-OCDMA allowing more than 40 users to be multiplexed compared to a non-coded 2D SAC-OCDMA system. This combination allowed us to increase the cardinality of the LDPC/SAC-OCDMA (W/S) system without using an optical hard limiter. [ABSTRACT FROM AUTHOR]

The excessively leached metal ions from traditional metallic antimicrobial nanoparticles are harmful to biological and human tissues. Metal-organic frameworks (MOFs) coordinating bioactive metal ions to organic bridging ligands can potentially address this issue, avoiding the excessive leaching of metal ions and simultaneously exhibiting high effective antibacterial activities. Here, we report the preparation of a 2-dimensional leaves-like zeolitic imidazolate framework (ZIF-L) for potential antibacterial and anti-algae applications. The ZIF-L nanosheet exhibits complete inactivation of Escherichia coli (phosphate buffer saline: 4 h) and Bacillus subtilis (seawater: 0.5 h). The ZIF-L/epoxy composite has excellent antibacterial effect, poisoning effect and anti-adhesion effect on a variety of marine algae. It is worth noting that the removal rate (Escherichia coli) for ZIF/epoxy composite can be reached to 90.20% by only adding ZIF-L (0.25 wt%). This work will inspire researchers to develop more metal-organic frameworks materials for applications in the antibacterial and anti-algae fields.

The calculation of motor temperature field is an essential part of motor design. The temperature rise of motor is related to the safety and stability of the whole system and related equipment. According to the parameters of the motor, the electromagnetic model of the motor is established to calculate the loss, and the loss is loaded into the two-dimensional model in the form of heat source density to calculate the motor temperature field. In order to improve the accuracy of temperature rise calculation, the equivalent thermal conductivity method is used to process the heat exchange in the air gap of the motor according to the structure characteristics of the moto. The accuracy of the equivalent thermal conductivity method is verified by comparing the simulation results with the experimental data. Fluent software is adopted to solve the two-dimensional temperature field model in a unidirectional coupling way. Finally, the temperature field data obtained by the experiment is compared with the simulation calculation results to verify the accuracy of the two-dimensional model to calculate the steady-state temperature field of the experimental motor. [ABSTRACT FROM AUTHOR]

A two dimensional spectral/spatial cyclic shift (2D-CS) optical code division multiple access (OCDMA) systems is proposed for a potentially next generation passive optical network (NG-PON) implementation called (2D-CS NG-OCDMA-PON) system. The2D-CS proposed code is characterized by a high capacity and a zero cross correlation property leads to completely eliminating the multiple access interference (MAI) effect that is considered as the main OCDMA system drawback. Firstly, the 2D-CScode construction is investigated from 1D-CS code. Secondly, a system description is provided by exhibiting the transmitter and receiver architecture in the PON context. Analytical analysis reveals that our proposed 2D-CScode outperforms similar codes such as perfect difference (2D-PD) and dynamic cyclic shift (2D-DCS) codes in terms of spectral efficiency, simultaneous network subscribers and data bit rate. In addition, based on numerical analysis 2D-CS NG-OCDMA-PON system shows a good system performance by means of avery low BER and a high Q-factor values equal to 10 - 26 and 10.41 dB, respectively. Likewise, for four users and free-amplification the achievable reach ability distance of the NG-OCDMA-PON system is 63.21 km, 43.57 km and 33.2 km while Q-factor is equal to 6 dB at a bit rate of 622 Mb/s, 1 Gb/s and 1.5 Gb/s, respectively. On the other side, according to the system setup the number of single mode fiber (SMF) is reduced to the half compared to other 2D-OCDMA-PON systems based on enhanced multi diagonal (EMD) and single weight ZCC (SWZCC) codes. [ABSTRACT FROM AUTHOR]

Comprehensive two-dimensional gas chromatography (GC × GC) is a mature analytical technique with a far greater separation capability than conventional one-dimensional methods. Atmospheric organic aerosols are comprised of a diverse range of substances which challenge one-dimensional analysis, and for which the two-dimensional method has proved very suitable. The review outlines the basic principles of the two-dimensional separation, and the instrumentation, including detectors. Time-of-flight mass spectrometry offers many advantages, especially with unknown mixtures, and has included use of low and high energy electron impact ionisation. The available methods of data reduction and analysis are outlined. GC × GC may be used in either targeted or untargeted modes, and studies have covered a very wide range of analytes, including many compound groups. Most common are studies of hydrocarbons, including polycyclic aromatic hydrocarbons (PAH), but other work has included oxygenates, chlorinated and nitrogen compounds, and diverse industrial chemicals and consumer products sampled across a range of environments. • Separation capability of GCxGC is ideally suited to organic aerosol analysis. • Nature of the hardware and data processing software is reviewed. • Recent advances include tandem EI ionisation at different electron energies. • Applications include both targeted and untargeted aerosol analysis. • Diverse compound groups have been studied in depth using ToF-MS detection. [ABSTRACT FROM AUTHOR]

Background: Echocardiography increasingly used for diagnosis of right atrial dilatation. Three dimensional is superior than two dimensional echocardiography. However, advances and new windows continues to emerge to increase its accuracy Aim of the work: to show the feasibility and accuracy of right parasternal approach and its usefulness in qualitative and quantitative assessments of right atrium in patients with right atrial dilatation in comparison with transesophageal approach. Patients and Methods: The study included thirty patients with right atrial dilatation. All patients underwent full history taking, clinical, 12-lead electro-cardiography and echocardiography. Transesophageal Echocardio-graphy was used as a gold standard for the accuracy of the right parasternal approach. Results: The study includes 30 patients with right atrial dilatation the right parasternal (RPS) view obtained in 18 patients (60%), and not obtained in 12 patients (40%). There was significant decrease of SVC anteroposterior minimal diameter (Min AP), crista terminalis (CT) width, CT length, right atrial appendage (RAA) base Maximum diameter and RAA base Minimum diameter, in 2D Echocardiography when compared to 3D Echocardiography. On the other side, there was no statistically significant difference in Right parasternal approach (3D) and Transesophageal approach. Conclusions: Parasternal approach is feasible in imaging right heart structures. In addition, three dimensional TTE had an incremental value over two dimensional TTE in the assessment of these structures

Abstract Compositional gradient can be described as changes in the composition of components both vertically and horizontally in a hydrocarbon reservoir. In the present work, two-dimensional compositional gradient in multi-component gas and oil mixtures is modeled. A thermodynamic model is developed based on molecular diffusion coefficients in mass diffusive flux. A combination of Sigmund and Bird correlations is considered to estimate molecular diffusion coefficients for gas mixtures. Implementing this comprehensive developed model on a gas condensate sample shows interesting differences not only in trends of component compositions but also in gradient magnitude. A real set of data from a supergiant gas condensate field is used to validate the model. It is perceived that the developed model reduces relative absolute errors to about 50%. In the next step, a comprehensive study was conducted to understand the cross effects of molecular diffusion and natural convection in gas condensate and volatile oil samples. Gas and oil samples are selected to investigate if natural convection has the same effects in different samples. It is observed that increase in natural convection causes to reduce horizontal and vertical composition gradients. This effect is more significant in gas reservoir, as methane composition varies by more than 5.2 mol% diagonally in gas condensate sample, whereas this value is about 0.45 mol% in volatile oil sample. Lower density and higher bulk velocity in gas sample cause more disturbances in flow streams of gas mixture. Evaluation of the developed model shows that the model is reliable for reservoir studies and management programs.

Employing the Density Functional Theory investigations, we have designed 2D α-CN with the dopants P, Si and B as catalyst for HER and OER activities. Doping of P and B over α-CN modifies its electronic properties and reduces band gap (3.78 eV) of α-CN to the required band gap for HER and OER activities. The modification of electronic properties is discussed by the analysis of partial density of states, Löwdin charge and charge density plot. To understand HER and OER activities better, we computed Gibbs free energy change after adsorption of H/O in various doped α-CN systems. We observe that the P doping at C site and B doping at N site of α-CN are best suited for HER and OER respectively. The HER (OER) activity increases by 88.33% (29.35%) for P doped at C site (B doped at N site) of α-CN in comparison to pristine α-CN. [Display omitted] • B, Si and P doping in 2D α-CN drastic reduces its electronic band gap. • P doping enhances the HER activity by 88.33% as compared to pristine 2D α-CN. • B doping enhances the OER activity by 29.35% as compared to pristine 2D α-CN. [ABSTRACT FROM AUTHOR]

In view of the calculation of starting characteristics of small asynchronous motor in different starting modes, the two-dimensional electromagnetic model is constructed based on the finite element method to simulate the starting characteristics of the motor. Considering the effect of the motor end on the overall electromagnetic simulation in the two-dimensional model, the parameterization of the resistance and leakage inductance of the stator and rotor end are equivalently processed to the model by the method of field circuit combination. The power models of direct starting, Y-Δ step-down starting and constant frequency voltage ratio starting are established by MagNet and Simulink software according to the starting circuit structure. The starting time, starting current and starting speed of the motor under different starting modes are compared and analyzed. The results show that the model can accurately simulate the characteristics of asynchronous motors under common starting methods. [ABSTRACT FROM AUTHOR]

We have prepared composites of CuCo2S4/GO/Fe2O3(Fe3O4) and applied them as an electrode for supercapacitor and as a magnetically recoverable Fenton catalyst towards dye degradation. The nanoplate structured CuCo2S4 was obtained by a simple hydrothermal approach, on which the electron transfer property was tuned by the addition of graphene oxide, and magnetic recoverability was induced by the loading of iron oxides (Fe2O3, Fe3O4) to form a ternary composite. On evaluating the behavior of the composites as a supercapacitor electrode material, the CuCo2S4/GO/Fe2O3 composite showed a good specific capacitance value of about 595 Fg− 1 at the current density of 1 Ag− 1 than the pure CuCo2S4 nanoplates along with good cyclic stability which showed 52% capacity retention even after 4000 cyclic experiments at 20Ag− 1. The composites were further utilized as a Fenton type catalyst towards the degradation of cationic dye rhodamine B (RhB). The CuCo2S4/GO composite showed the remarkable removal efficiency of about 99.34% within 20 min of reaction time. The obtained results show us that the ternary CuCo2S4/GO/Fe2O3 (Fe3O4) composites would serve as an ideal material for energy and environmental applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) metal–organic frameworks (MOFs) have emerged as intriguing 2D materials because of their specific features of 2D morphology and designable skeletons, which have elicited great interest in environment remediation. In this work, 2D MOF nanosheets are fabricated via a mixed-solvent solvothermal method, and a regulation strategy of metal inorganic clusters on MOFs is used to construct two different 2D MOFs with monometallic and bimetallic coordination, that is, Ni-MOF and Ni/Cd-MOF. Binary metal coordination renders more crystal defects and vacancies in the framework; thus, compared to monometallic Ni-MOF, bimetallic Ni/Cd-MOF exhibits fewer layers (4∼5 layers), higher specific surface area, larger pore size, and higher surface electronegativity, which leads to its excellent adsorption removal for Pb2+, with higher adsorption rate and affinity, and superior adsorption capacity (950.61 mg/g, almost twice as high as that of monometallic Ni-MOF). Besides, the adsorption mechanism further confirmed that the carboxyl groups (−COO−) from organic linker on 2D MOFs serve as the main binding sites for Pb2+ coordination, and bimetallic Ni/Cd-MOF has more active −COO− sites for Pb2+ capture. Thus, the bimetallic Ni/Cd-MOF regulated by heterogeneous metal atoms shows promising application for highly efficient adsorption of heavy metal ions.

Full exploitation of two-dimensional (2D) semiconducting MoSe2, an exciting 2D transition-metal dichalcogenide, in optoelectronics is hampered because of dearth of scalable production methods. Here, a redox-mediated green route growth of ultrathin MoSe2 nanosheets and nanocrystals is reported. At solvothermal condition, molybdenum acetate [(CH3COO–)2Mo2+]2 at (+II) oxidation state is employed as the molybdenum source for the first time to grow 2D MoSe2 of 2H phase. Edible olive oil acts as a solvent as well as a ligand to block the growth in the Z direction, leading to the formation of 2D MoSe2. The bottom-up solution-processed method differs distinctly from other available synthesis methods in terms of the 2D MoSe2 nanosheet growth of the semiconducting phase (2H) without using any template or any external reducing agent. Evolution of MoSe2 nanosheets is systematically studied by X-ray diffraction and Raman spectroscopy with the variation of the reaction temperature and the reaction time. Prolonged sonication and gradient centrifugations enable in obtaining MoSe2 nanocrystals of different sizes. Tuneable optical properties and temperature-dependent emissions of MoSe2 nanocrystals and nanosheets are studied by UV–visible and photoluminescence spectroscopies. Finally, we have fabricated a photoconductive device which shows broadband visible light detection, demonstrating the potential use of bottom-up solution-processed semiconducting MoSe2 in broadband photodetection applications. [ABSTRACT FROM AUTHOR]

It still remains a challenge to simultaneously optimize the nanostructure and electronic structure of electrocatalysts of noble‐metal‐based electrocatalysts to improve their performance and reduce their noble metal loadings, in which the dispersion and activity of the noble metal components play an important role. A series of hybrids of noble metal nanocrystals (NMNCs) and two‐dimensional metal‐organic framework (2D MOF) nanosheets are designed and synthesized by a facile, fast, and general approach, in which NMNC dispersion is quickly mixed with MOF precursors at room temperature. The NMNCs/2D MOF hybrids, denoted as M‐Ni‐NS (M = Ir, Ru or Pt, etc.), are assembled by taking advantage of abundant O‐atom arrays on the surface the of 2D MOF nanosheets and they enable excellent dispersity and stability. Experimental and computational results show that the M‐O‐Ni bridging bonds realize successful tuning of the electronic structure of active sites and modify their activity. Taken together with the merits of the nanostructure of the 2D MOF support, this multiscale optimization strategy produces Ir‐Ni‐NS electrocatalysts with excellent performance for the oxygen evolution reaction, achieving a low overpotential of 270 mV at 10 mA cm−2 in alkaline media and long time stability. [ABSTRACT FROM AUTHOR]

Orthogonal time-frequency-space (OTFS) modulation has shown significant error performance advantages over orthogonal frequency division multiplexing (OFDM) in time-varying channels. However, the symbols in OTFS frames still suffer from inter-Doppler interference (IDI) and inter-symbol interference (ISI). In this letter, we propose a two dimensional (2D) adaptive multichannel decision feedback equalizer (DFE) to combat the interference. The proposed receiver constructs the input signal and feedback signal of the DFE based on the characteristic of OTFS modulation. Meanwhile, by exploiting the sparsity feature of the channels in delay-Doppler domain, the iterative improved proportionate normalized least mean squares (IPNLMS) algorithm is employed to achieve fast convergence and fast tracking. The simulation results show that the proposed equalizer could achieve satisfied BER performance with lower complexity. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) superconductors are important both for the basic understanding of pairing mechanism and potential applications in nanosuperconducting quantum interference devices. In this work, we explore the phonon-mediated superconductivity of hole-doped and lithium-deposited monolayer BC2N by first-principles calculations. Our results reveal that the hole-doped planar BC2N cannot superconduct due to weak electron–phonon coupling (EPC) with λ = 0.07. When lithium is deposited on the monolayer, the EPC constant is enhanced significantly to 0.52 and the superconducting transition temperature Tc is determined to be 3.58 K. Because more phonons, in particular the out-of-plane modes, are triggered to participate in the EPC process, the Tc is higher than 1.4 K of Ca-deposited graphene, 1.3 K of Li-deposited stanene, and 3 K of doped WS2 and NbSe2. It is also found that tensile biaxial strain weakens the EPC and leads to a decreased superconducting transition temperature. Our findings will provide a new guideline for designing novel 2D superconductors and enrich the potential application of 2D BC2N. [ABSTRACT FROM AUTHOR]