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Purpose of Review: Two-dimensional (2D) echocardiography and Doppler echocardiography are important tools for cardiac evaluation unfortunately affected by artifacts, which can obscure pathology. Certain artifacts may be inevitable, but others can be diminished by changing the probe position. Recent Findings: Common 2D imaging artifacts include shadowing and enhancement. There are a variety of reverberation artifacts, ranging from comet tail to mirroring, that result in atypical duplication. At the same time, device and electronic interference create unique interference patterns. Doppler imaging has its own specific artifacts. These can alter spectral graphs, such as aliasing, or be seen on color Doppler imaging, such as pseudoflow or blooming. Summary: Misinterpreting artifacts can result in improper management; thus, recognition is crucial. However, some artifacts can even be beneficial for evaluation and decision-making. We provide a review of artifacts in 2D and Doppler echocardiography for this reason. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) crystalline growth of transition metal dichalcogenides (TMDs) by atmospheric pressure chemical vapor deposition (APCVD) is highly sensitive to any changes in growth parameters. At an optimized growth temperature and transition metal flux, 2D compact domains grow primarily triangular/hexagonal in shape that transform into dendritic structures at higher transition metal flux. With changes in the local flux (or, local chalcogen-to-transition metal vapor ratio), domain morphologies on the substrate vary with distance for locations away from the center. In this work, phase field simulations are carried out to emulate experimentally observed morphology evolution as a function of transition metal flux. Our model demonstrates the critical roles of precursor flux and attachment time in controlling the domain morphologies which is further established by fractal dimension analysis. Evolution of patterns simulated as a function of flux and attachment time can help to identify more precise combination of growth parameters leading to a specific growth mode. Consistent with the experimental observations, the model also reproduces the interaction among multiple domains. Our findings could be useful for achieving controlled growth of 2D domains with desired shape (compact or dendritic) as required for the next-generation electronic and optoelectronic devices, and efficient catalytic applications. [ABSTRACT FROM AUTHOR]

A sulfhydryl monomicelles interfacial assembly strategy is presented for the synthesis of fully exposed single‐atom‐layer Pt clusters on 2D mesoporous TiO2 (SAL‐Pt@mTiO2) nanosheets. This synthesis features the introduction of the sulfhydryl group in monomicelles to finely realize the controllable co‐assembly process of Pt precursors within ordered mesostructures. The resultant SAL‐Pt@mTiO2 shows uniform SAL Pt clusters (≈1.2 nm) anchored in ultrathin 2D nanosheets (≈7 nm) with a high surface area (139 m2 g−1), a large pore size (≈25 nm) and a high dispersion (≈99 %). Moreover, this strategy is universal for the synthesis of other SAL metal clusters (Pd and Au) on 2D mTiO2 with high exposure and accessibility. When used as a catalyst for hydrogenation of 4‐nitrostyrene, the SAL‐Pt@mTiO2 shows a high catalytic activity (TOF up to 2424 h−1), 100 % selectivity for 4‐aminostyrene, good stability, and anti‐resistance to thiourea poisoning under relatively mild conditions (25 °C, 10 bar). [ABSTRACT FROM AUTHOR]

Dopant levels in layered compound InSe have considerable potential in optoelectronic devices. Dopant‐induced trap states are essential in determining the optoelectrical properties of semiconductors. However, detailed studies of the persistent photoconductivity (PPC) and related mechanism in doped InSe are still not available. Here, the dependence of excitation energy on the shallow donor level caused by the dopants (Ge, Sn) in InSe is systematically investigated. Notably, prolonged decay time originates from extrinsic Ge, Sn dopants and these doping‐assisted states improve the optoelectrical performance of pristine InSe. Those photogenerated carriers are trapped in the Ge, Sn shallow impurities states, which are long‐lived enough to be extracted into Au contacts before annihilation. This renders Ge‐, Sn‐doped InSe photoconductive gain and maximized photocurrent. Sn‐doped InSe single crystal device can achieve a maximum responsivity of around 1.7 × 106 A W−1 under red light and detectivity of 6.18 × 1013 Jones. In addition, Hall measurements identify the carrier concentration and the Hall mobility of pristine InSe is significantly changed by Ge and Sn dopants. It is demonstrated that doping Ge, Sn atoms is responsible for the obvious photoconductivity and beneficial for the high‐performance photodetector, offering intriguing opportunities for novel holographic memory applications. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study is to examine the application value of two‐dimensional (2D) and high‐definition live (HDlive) flow combined with spatiotemporal image correlation (STIC) in diagnosing fetal total anomalous pulmonary venous connection (TAPVC). Methods: Seventeen cases of fetal TAPVC were diagnosed using 2D and HDlive Flow combined with STIC. These cases were then retrospectively analyzed to examine the value of using 2D and HDlive Flow combined with STIC in the diagnosis of TAPVC. Results: 2D and HDlive Flow combined with STIC detected 13 cases of supracardiac TAPVC (two isolated cases, seven cases with right atrial isomerism (RAI), four cases with other complex malformations), one case of isolated intra‐cardiac TAPVC, and three cases of cardiac TAPVC (two isolated cases and one case with complex congenital heart anomaly). Small left atrium (LA), the absence of PVs drainage into the LA and the increased retroatrial distance between LA and the descending aorta (DAo) were significant signs that should raise the suspicion of fetal TAPVC. HDlive Flow combined with STIC can dynamically display the TAPVC which may assit the prenatal diagnosis of TAPVC. Conclusion: 2D and HDlive Flow combined with STIC can assit the diagnosis of fetal TAPVC abnormalities and has important clinical value. [ABSTRACT FROM AUTHOR]

Two-dimensional layered materials have attracted increasing attention due to their unique structures and outstanding mechanical and physical properties. Transition metal dichalcogenides (TMDs) possess unique physical properties and optical properties that meet the basic requirements of photodetectors. As representative TMDs, MoS2 has excellent mechanical properties due to its strong covalent bonds and great elasticity. The monolayer MoS2 has a direct bandgap of around 1.8 eV. In addition, MoS2-based optoelectronic devices have high switching ratio and carrier mobility. However, due to the characteristic of atomic-scale thickness, the light-harvesting ability of layered TMDs is very weak, which largely limits the responsivity and detection rate of photodetectors, thus inhibiting the practical application of such devices. The slow photo response rate is also a problem that often occurs in TMDs devices. Researchers have reported several strategies to improve the performance of TMDs-based photodetectors. At present, there are two main optimization schemes, namely surface modification, and heterostructure construction. The utilization of metal plasmon effect and the construction of heterojunctions are both effective means to improve the performance of MoS2 photodetectors. These schemes can improve the light absorption capability of MoS2 and broaden the range of light detection. However, there are also disadvantages of the complex processes and limited enhancement effects in large-area fabrication. Therefore, it is of vital significance to further explore the response range and performance of MoS2 photodetectors. [ABSTRACT FROM AUTHOR]

Perovskite/silicon (Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional (3D) hybrid perovskite seriously hinders the lifetimes of tandem devices. In this work, the quasi-two-dimensional (2D) (BA)2(MA) n â€" 1Pb n I3 n + 1 (n = 1, 2, 3, 4, 5) (where MA denotes methylammonium and BA represents butylammonium), with senior stability and wider bandgap, are first used as an absorber of semitransparent top perovskite solar cells (PSCs) to construct a four-terminal (4T) tandem devices with a bottom Si-heterojunction cell. The device model is established by Silvaco Atlas based on experimental parameters. Simulation results show that in the optimized tandem device, the top cell (n = 4) obtains a power conversion efficiency (PCE) of 17.39% and the Si bottom cell shows a PCE of 11.44%, thus an overall PCE of 28.83%. Furthermore, by introducing a 90-nm lithium fluoride (LiF) anti-reflection layer to reduce the surface reflection loss, the current density (J sc) of the top cell is enhanced from 15.56 mA/cm2 to 17.09 mA/cm2, the corresponding PCE reaches 19.05%, and the tandem PCE increases to 30.58%. Simultaneously, in the cases of n = 3, 4, and 5, all the tandem PCEs exceed the limiting theoretical efficiency of Si cells. Therefore, the 4T quasi-2D perovskite/Si devices provide a more cost-effective tandem strategy and long-term stability solutions. [ABSTRACT FROM AUTHOR]

Fabricating hierarchical nanomaterials by self-assembly of rod-coil block copolymers attracts great interest. However, the key factors that affect the formation of the hierarchical nanomaterials have not been thoroughly researched. Herein, we have synthesized two diblock copolymers composed of poly(3-hexylthiophene) (P3HT) and polyethylene glycol (PEG). Through a heating, cooling, and aging process, a series of multilayered hierarchical micelles and fibers were prepared in alcoholic solutions. The transition from fibers to hierarchical micelles are strictly influenced by the strength of the π-π stacking interaction, the PEG chain length, and solvent. In isopropanol, the P3HT22-b-PEG43 could self-assemble into hierarchical micelles composed of several two-dimensional (2D) laminar layers, driven by the π-π stacking interaction and van der Waals force. The P3HT22-b-PEG43 could not self-assemble into well-defined nanostructures in methanol and ethanol, but could self-assemble into fibers in isobutanol. However, the P3HT22-b-PEG113 with a longer corona block only self-assembled into fibers in four alcoholic solutions, due to the increase in dissolving capacity and steric hindrance. The sizes and the size distributions of the nanostructures both increased with the increase in polymer concentration and the decrease in solvent polarity. This study shows a method to fabricate the hierarchical micelles. [ABSTRACT FROM AUTHOR]

Two-dimensional materials have excellent electronic and optical properties, suggesting absolute advantages in nanodevices. In this work, a new two-dimensional material with a puckered structure, a C 2 B 6 monolayer, is proposed. The material presents dynamic and thermal stability calculated by first-principle simulations. Interestingly, the C 2 B 6 monolayer possesses semiconductor behavior with an ultra-narrow bandgap of approximately 0.671 eV by HSE06 functional. Meanwhile, the hole in the C 2 B 6 monolayer shows ultrahigh mobility at approximately 6,342 cm 2 ⋅V -1 ⋅s -1 in decent transport directions, which is larger than traditional transition metal dichalcogenides materials. More importantly, the pronounced anisotropy of mobility of the electrons and holes can separate the photogenerated charges, suggesting the applications for photocatalytic, photovoltaic and optical and cold chain electronic devices. Then, the novel properties of the light absorption characteristic are obtained, and the anisotropic photocurrent implies the C 2 B 6 monolayer can be used as a potential photoelectric device. Our results provide theoretical guidance for the design and application of two-dimensional materials., Competing Interests: Author QS was employed by Nanjing Boya Intelligent Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Xu, Zhu, Zheng, Sun, Ma, Mu and Cui.)

Using a first-principles approach, this study delves into the effects of strain and electrostatic doping on the electronic and magnetic properties of the GaN/VTe 2 van der Waals (vdW) heterostructure. The results reveal that when the GaN/VTe 2 vdW heterostructure is doped with 0.1 h /0.2 h of electrostatic charge, its magnetization direction undergoes a remarkable reversal, shifting from out-of-plane orientation to in-plane direction. Therefore, we conduct a thorough investigation into the influence of electron orbitals on magnetic anisotropy energy. In addition, as the strain changes from -1% to 1%, the 100% spin polarization region of the GaN/VTe 2 vdW heterostructure becomes smaller. It is worth noting that at a doping concentration of 0.1 h , the GaN/VTe 2 vdW heterostructure has a Curie temperature of 30 K above room temperature. This comprehensive study provides valuable insights and provides a reference for analyzing the electronic and magnetic properties of low-dimensional systems., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Two-dimensional (2D) halide perovskites have become a promising class of memristive materials due to their low power consumption, compositional versatility, and microstructural anisotropy in electronics. However, implementing high-performance resistive random-access memory requires a higher reliability and moisture resistance. To address these issues, component studies and attempts to improve the phase stability have been reported but have not been able to achieve sufficient reliability. Here, highly textured thin films grown perpendicular to the substrate in Ruddlesden-Popper 2D perovskites exhibited highly stable and reliable binary memory performance. We further built a flexible crossbar array to verify data storage capability, achieving a high device yield, robust endurance, long retention, reliability to operate under bending conditions, and moisture stability over a year. These device performances are attributed to preformed vertically oriented nanocrystals that allow the conductive filaments to operate reliably. Our finding provides the material design strategy that can be extended to the development of semiconductor materials for next-generation memory devices.

The discovery of novel materials with high gas sensing selectivity is a key driver of gas sensor technology. Based on the recently reported two-dimensional (2D) pentagonal BeP 2 , we introduce penta-BeAs 2 as a new member of the pentagonal family of materials for toxic gas sensors based on density functional theory (DFT). For electronic applications, a band structure calculation showed that penta-BeAs 2 has indirect band gaps of 0.38 and 0.79 eV, using GGA-PBE or HSE functionals. Stability analysis confirmed that penta-BeAs 2 is dynamically, mechanically, and thermally stable. The adsorption of toxic gases (CO, NO, and NO 2 ) and nontoxic gases (H 2 , N 2 , H 2 O, and CO 2 ) on the penta-BeAs 2 monolayer was studied. The contrasting adsorption behavior observed between toxic and nontoxic gases on penta-BeAs 2 (physisorption vs chemisorption) underscores its high selectivity for toxic gas-sensing applications. Adsorption energies for toxic gases fall within a moderate range (0.4-0.8 eV), indicating good reversibility and short recovery times at room temperature. Additionally, the quantum transport properties of penta-BeAs 2 were studied using the nonequilibrium Green's function (NEGF) approach, confirming strong sensitivity and selectivity toward toxic gases.

The method of moments generates a matrix which is usually solved using iterative methods due to the high computational complexity of a direct inversion. The cost of matrix-vector multiplications and memory requirement at each iteration step is proportional to O(N2), where N is the number of unknowns in the problem. To reduce the computational complexity, the Green’s function is approximated using Fourier series. This will allow to separate the source points from the observation points. Hence, aggregate all source points and then multiply it with each observation point with a small adjustment in the aggregation term. The proposed method is tested by solving electromagnetic wave scattering from perfect conductor two-dimensional basic canonical shape, i.e., circular cylinder. The results showed that the proposed method is accurate and for large N it has a computational complexity less than the direct matrix-vector multiplication.

Abstract Two‐dimensional (2D) layered transition metal carbides/nitrides, called MXenes, are attractive alternative electrode materials for electrochemical energy storage. Owing to their metallic electrical conductivity and low ion diffusion barrier, MXenes are promising anode materials for sodium‐ion batteries (SIBs). Herein, we report on a new 2D carbonitride MXene, viz., Ti2C0.5N0.5Tx (Tx stands for surface terminations), and the only second carbonitride after Ti3CNTx so far. A new type of in situ HF (HCl/KF) etching condition was employed to synthesize multilayer Ti2C0.5N0.5Tx powders from Ti2AlC0.5N0.5. Spontaneous intercalation of tetramethylammonium followed by sonication in water allowed for large‐scale delamination of this new titanium carbonitride into 2D sheets. Multilayer Ti2C0.5N0.5Tx powders showed higher specific capacities and larger electroactive surface area than those of Ti2CTx powders. Multilayer Ti2C0.5N0.5Tx powders show a specific capacity of 182 mAh g−1 at 20 mA g−1, the highest among all reported MXene electrodes as SIBs with excellent cycling stability.

The excellent intrinsic properties of two-dimensional MXenes, such as hydrophilic, good electrical and thermal conductivity, excellent film forming ability, render them potential candidates for many innovations in different areas. High-quality MXene plays an important role in enhancing the devices’ performances in various applications. However, the synthesis of high-quality MXenes has not been well documented. Herein, we summarize the up-to-date preparation strategies of MXene and compare their respective advantages and disadvantages. We particularly outline the criteria of high-quality MXenes, and focus on the influence of different synthetic methods on the surface functional groups, morphology (size and defect), layer spacing of MXene, etc. The challenges on MXenes’ preparation and their future perspectives are also provided. We anticipate this perspective will provide prospective guidance for synthesizing desirable high-quality MXenes.

In this study, two-dimensional (2D) MXene material (Ti3C2Tx) was employed to investigate its potentials toward the Cr(VI) removal in aqueous system by batch experiments. Characterization techniques such as SEM-EDS, HRTEM, XRD, FI-TR and XPS were used to analyze the structure and interaction of Ti3C2Tx before and after Cr(VI) adsorption. The results indicated that the layered structure of Ti3C2Tx had unique surface functional properties and abundant active sites, such as –OH, Ti–O, C = O, which exhibited high adsorption capacity for Cr(VI) removal. The Cr(VI) adsorption capacity by Ti3C2Tx decreased with the increase of pH, and its maximum value can reach 169.8 mg/g at pH = 2.0. The adsorption kinetic was well-explained by a pseudo-second-order kinetic, indicating that chemical interaction played a dominant role in the adsorption of Cr(VI) on Ti3C2Tx. Meanwhile, the isotherm data was calculated to conform to the Freundlich isotherm model. Thermodynamic analysis indicated that the adsorption process of Cr(VI) on Ti3C2Tx was a spontaneous endothermic process. These experimental results revealed that Ti3C2Tx had tremendous potential in heavy metals adsorption from aqueous solutions. HIGHLIGHTS Novel Two-dimensional titanium carbide nanosheets (Ti3C2Tx MXene) were employed for Cr(VI) scavenging.; Ti3C2Tx MXene exhibited high adsorption ability for the Cr(VI) removal, namely 169.8 mg/g at pH = 2.0.; The adsorption of Cr(VI) on Ti3C2Tx MXene is a multilayer adsorption and spontaneous endothermic process.; The chemical interaction played a dominant role in the Cr(VI) removal by Ti3C2Tx MXene.;

Two-dimensional (2D) lead halide perovskites have garnered increasing interest due to their high photoluminescence quantum yields and tunable luminescence characters, making them excellent materials in light-emitting, especially for white-light emission. In contrast to their 3D analogues, they are formed by inserting large organic cations between the anionic layers of lead halide octahedra. Herein, we designed and prepared AVA2PbClxBr4-x (x = 0, 1, 2, 3, 4) alloy perovskites, in which AVA (5-aminovaleric acid) was used as an organic cation to separate the layers of chlorine-substituted lead bromide 2D perovskite, in order to identify the role of Cl substitution in tuning the bandgap and luminescence characters of the 2D AVA2PbBr4 perovskite. X-ray diffraction measurements revealed achievement of single-phase thin films of AVA2PbClxBr4-x perovskites with a (001) orientation. With increasing Cl/Br ratio from 0 to 1, the lattice constant c was found to decrease from 1.672 nm to 1.597 nm following c(x) = 1.674 – 0.076x, while the bandgap increased from 3.11 eV to 3.76 eV as approximated with Eg(x) = 3.08 + 0.62x. Correspondingly, the alloy luminescence character evolved from narrow-band blue-violet to broadband white-light emission, which was attributed to transformation from free-exciton to self-trapped-exciton emission with increasing octahedral distortion caused by Cl substitution. Based on an alloy system with continuously varying content designed for the first time, the work highlighted the role of Cl incorporation in changing the crystal lattice structure, and tuning bandgap as well as the light emission characters in 2D lead halide perovskites.

Zinc manganese oxide (ZMO) system represents a notable family of mixed transition metal oxides (MTMOs) because of their superiority of the high theoretical capacity, adequacy of natural content, and low cost. However, the methods to match both the reliable synthesis and the designable construction of large-sized two-dimensional (2D) ZMO nanosheets are still considered as grand challenges. Herein, we have successfully realized the preparation of 2D ZMO nanosheets with large lateral sizes up to ∼20 μm by simple pyrolysis of 2D metal–organic framework (MOF) nanosheets precursor. The growth mechanism of 2D MOF is proposed to be based on the lamellar micelles formed by polyvinyl pyrrolidone (PVP). The obtained 2D and porous ZMO nanosheets exhibit high specific capacity as well as good rate capability. More importantly, the as-prepared ZMO electrode shows a remarkable capacity increment upon cycling (from 832 mAh g−1 at the 2nd cycle to 1418 mAh g−1 at the 700th cycle, at 1 A g−1). Through simple adjustment of the calcination temperature, the valence state of Mn species in the yielding ZMO samples can be fine-tuned. Through systematic investigation towards these ZMOs containing different Mn species, the extra specific capacity is revealed to be chiefly on account of the arising of the valence state of Mn upon the cycling process. Moreover, it is disclosed that the higher-valent Mn the pristine ZMO contains, the more additional capacity it gains upon cycling. We believe that this work will inspire more detailed analysis on the relationship between the valence state of Mn and extra capacity.

Background: Midline cerebral structures are essential for the normal morphogenesis and function of the fetal brain. However, the diagnosis of congenital anomalies of midline cerebral structures. The Aim of The Work: This study aimed to evaluate the role of 2D versus 4D ultrasound in the diagnosis of midline structures of the fetal brain at the second trimester of pregnancy.Patients and Methods: 200 pregnant women at the second trimester [18-22 weeks] were selected. They were clinically evaluated to check the female and fetal wellbeing. Then a screening of fetal brain midline strictures had been performed by two- and four-dimensional ultrasound, aiming to discover any anomalies of the fetal brain midline structure. Both scans were compared with the postnatal transcranial ultrasound.Results: The 2D ultrasound detected no abnormality in 194 out of 200 fetuses [97.0%], and 4 cases [2.0%] had mega-cisterna magna, and 2 cases [1.0%] had encephalomylocele, which were detected by the 4 D and confirmed by postnatal transcranial ultrasound. The 4 D US discovered 2 cases [1.0%] of Dandywalker malformation, which was confirmed by postnatal transcranial US. There was a complete agreement between prenatal 4D ultrasound and postnatal transcranial ultrasound. The prenatal 2D ultrasound had a sensitivity of 75.0%, specificity of 100.0%, PPV of 100.0%, NPV of 98.7% and overall accuracy of 99.0%. Otherwise, the prenatal 4D ultrasound was 100.0% sensitive and specific. Conclusion: 4D ultrasound showed superiority in the diagnosis and confirmation of the fetal brain midline structure’s abnormalities. Also, the prenatal 4D ultrasound was 100.0% sensitive as postnatal transcranial US.

Since the innovative development of photosensitizers (PSs) is pivotal prerequisite for the successful clinical translation of photodynamic therapy (PDT), the unresolved challenges of classical PSs such as photobleaching, poor bioavailability, lack of tumor selectivity encourage the exploitation of new-generation PSs. In this work, we develop silicene nanosheets with unparalleled physiochemical nature and intriguing biocompatibility as the distinct two-dimensional (2D) nanoscale photosensitizer based on the mechanism of wet-chemical synthetic approach to achieve effective PDT-based tumor nanotherapy. The generation capacities of singlet oxygen (1O2) in different atmospheres have been systematically explored in depth. Furthermore, the conjunction of c (RGDyC) onto 2D silicene nanosheets (denoted as SRGD) endows the SRGD nanomedicines with specific targeting properties to αvβ3 integrin-overexpressed cancer cells, accomplishing in vivo and in vitro potent tumor growth inhibition efficiency. More notably, the excellent light absorption capacity of 2D silicene enables the tumor-specific photoacoustic imaging for potentiating the therapeutic guidance and monitoring. This paradigm can inspire the future design and applications of 2D silicene-based cancer-theranostic nanoplatform in biology and medicine.

Abstract Manganese sulfides (MnS) are particularly appealing electrode candidates for lithium/sodium‐ion batteries, because of their low cost, wide availability, and environmental benignity. Herein, well‐defined Mn(OH)(OCH3) nanoflakes are synthesized for the first time, whereby two‐dimensional (2D) porous α‐MnS and its composite with N, S co‐doped carbon (α‐MnS@NSC) are produced via the topologic sulfurization of Mn(OH)(OCH3) or a Mn(OH)(OCH3)@polydopamine intermediate. The electrochemical lithium/sodium‐storage properties of α‐MnS are most likely governed by the conductivity, and thus can be significantly enhanced through integrating with conductive carbon coating. As a result, α‐MnS@NSC outperforms the bare α‐MnS and most of the reported MnS‐based anodes, demonstrating the high reversible capacities (1275 mA h g−1 at 0.2 A g−1 for LIBs and 581 mA h g−1 at 0.1 A g−1 for SIBs), great rate capability, and long cyclabilities. This work showcases both a novel strategy to fabricate 2D manganese‐based compounds and a preferred architecture for high performance lithium/sodium‐ion batteries.

Two-dimensional (2D) material is the promising for next-generation information technology. The recently discovered intrinsic magnetic crystals have simulated a renaissance in 2D spintronics, which provides an ideal platform for exploring novel physical phenomena. However, current experimental trial-and-error methods in discovering new spintronic material are still very expensive and challenging. In contrast, based on well-developed first-principles calculations, computationally designing the spintronic materials provides a more efficient way for exploring new ferromagnetic (FM) materials and understanding the nature of magnetic properties. Several predictions, such as CrI3 monolayer, CrGeTe3 bilayer, CrSBr monolayer, FeCl2 monolayer, and Fe3GeTe2 monolayer have been confirmed by experiments, showing the great performance of computational approaches. This minireview article attempts to give a brief of discovering intrinsic 2D spintronics from theoretical aspect, and in particular, we emphasize roles played by calculation based on first-principles methods in designing 2D FM materials and devices. The current challenges and proposals on future developments of 2D spintronics are also discussed.

Among typical energy storage devices, supercapacitors play a predominant role in industry and our life owing to their rapid charge/discharge rate, superior lifespan, high power density, low cost, and outstanding safety. However, their low energy density has severely hindered their further development. For active electrode materials, graphene-based mesoporous nanosheets (GMNs) can combine the advantages from graphene and mesoporous materials, which can be applied to significantly enhance the energy density of supercapacitors. Here, we review the recent advances in GMNs for supercapacitors, focusing on in-plane mesoporous graphene and sandwich-like graphene-based heterostructures. Firstly, the synthesis of in-plane mesoporous graphene with ordered and disordered mesopores for supercapacitors is introduced. Secondly, sandwich-like graphene-based heterostructures are classified into mesoporous carbon/graphene, mesoporous heteroatom-doped carbon/graphene, mesoporous conducting polymer/graphene, and mesoporous metal oxide/graphene, and their applications in supercapacitors are discussed in detail. Finally, the challenges and opportunities of GMNs for high-performance supercapacitors are proposed.

The escalating urgency to mitigate climate change and enhance energy security has prompted heightened exploration of hydrogen production via electrocatalysis as a viable alternative to conventional fossil fuels. Among the myriad of electrocatalysts under investigation, two-dimensional (2D) metal–organic frameworks (MOFs) stand out as a particularly appealing option. Their unique properties, including a large active specific surface area, distinctive pore structure, ample metal active sites, ultra-thin thickness, superior ion transport efficiency, fast electron transfer rate, and the ability to control the morphological synthesis, endow these frameworks with exceptional versatility and promising potential for electrocatalytic applications. In this review, we delineate the structural features and advantages of 2D MOFs and their derivatives. We proceed to summarize the latest advancements in the synthesis and utilization of these materials for electrocatalytic hydrogen evolution reactions (HER) and oxygen evolution reactions (OER). Finally, we scrutinize the potential and challenges inherent to 2D MOFs and their derivatives in practical applications, underscoring the imperative for continued research in this captivating field of electrocatalysis.

Membrane separation is a central area of research in chemical engineering because of its important status as the key technology in chemical separation and water treatment processes. Recently, polymeric graphitic carbon nitride (g-C3N4) has emerged as a candidate material for membrane applications because of its appealing physiochemical properties and ease of fabrication. Herein we review the progress of g-C3N4-based membranes, including the peculiarity of two-dimensional (2D) g-C3N4, the tailoring of functionality, and integration into membrane stacks for practical applications in gas separation, water purification, pervaporation, photocatalytic water filtration, oil-in-water separation, and polymer electrolyte membranes. Moreover, possible development directions of g-C3N4-based membranes are discussed along with the current challenges and future perspectives. [ABSTRACT FROM AUTHOR]

Photocatalytic CO 2 reduction to fuels and valuable chemicals by two-dimensional (2D) covalent organic framework nanosheets (CONs) is gathering much attention. However, it is still a challenge to improve photocatalytic performance. Herein, cobalt and nickel coordinated guanidinium-based 2D covalent organic framework nanosheets were synthesized by the condensation reaction between triformylphloroglucinol (TP) and triaminoguanidine (TG). In photocatalytic CO 2 reduction, CO 2 could be converted to CO effectively by using the prepared cobalt and nickel coordinated 2D CONs as photocatalyst. In particular, cobalt coordinated 2D guanidinium-based CONs (denoted as Co-TPTG Cl) was the most effective, CO and H 2 production rate reached up to 14641 μ mol mg-1 h-1 and 7968 μ mol mg-1 h-1, respectively. Compared with Ni-based catalyst, Co-based catalysts exhibited better catalytic performance in the photocatalytic CO 2 reduction. From the characterizations of fluorescence spectroscopy and CO 2 absorption-desorption isotherm, Co-TPTG Cl 2D CONs owns longer fluorescence lifetimes and better absorption capacity of CO 2. [Display omitted] • Cobalt and nickel coordinated guanidinium-based 2D CONs were prepared. • CO production rate reached up to 14641 μ mol mg-1 h-1 with Co-TPTG Cl as catalyst. • The recombination of photogenerated electrons and holes was inhibited effectively. [ABSTRACT FROM AUTHOR]

Torsional oscillator (TO) is an experimental technique which is widely used to investigate superfluid responses in helium systems confined in porous materials or adsorbed on substrates. In these systems, heat capacity (HC) is also an important quantity to study the local thermodynamic properties. We have developed a simple method to incorporate the capability of HC measurement into an existing TO without modifying the TO itself. By inserting a rigid thermal isolation support made of alumina and a weak thermal link made of fine copper wires between a standard TO and the mixing chamber of a dilution refrigerator in parallel, we were able to carry out simultaneous TO and HC measurements on exactly the same helium sample, i.e., four atomic layers of 4He adsorbed on graphite, with good accuracies down to 30 mK. The data reproduced very well the previous workers' results obtained independently using setups optimized for individual measurements. This method is conveniently applicable to a variety of experiments where careful comparisons between results of TO and HC measurements are crucial. We describe how to design the thermal isolation support and the weak thermal link to manage conflicting requirements in the two techniques. [ABSTRACT FROM AUTHOR]

Tuning the nanostructure of anode material is one of the most effective ways to promote energy storage performance in the field of lithium-ion batteries. Herein, two-dimensional (2D) MoNb12O33 (MNO) material synthesized by combining a hydrothermal method and high-temperature calcination treatment is reported as a potential candidate anode material for lithium-ion batteries. Compared with other niobium-based oxide, Mo has higher valence and higher conductivity, which is very beneficial for maintaining its own good electrochemical performance. The sheet-like structure with abundant holes is favorable for the sufficient connection between MNO nanoparticles and electrolyte, further enhancing the kinetics of the lithium-ion diffusion process, thus giving rise to even better electrochemical performance. Benefitting the elegant structure, the charge–discharge capacity of MNO is maintained separately at 60.74 mA h g−1 and 61.26 mA h g−1 after 1000 cycles at 10 C, and the coulomb efficiency is close to 100%. The lamellar MNO fabricated by the facile method in this work displays great promise for application in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Designing a heterostructure photoanode with an appropriate band alignment, a beneficial charge migration pathway, and an adequate interfacial coupling is crucial for photoelectrochemical (PEC) energy conversion. Herein, we fabricate a hetero-nanostructure photoanode with CdS nanorods (CdS NRs) and two-dimensional (2D) ZnIn2S4 nanosheets (ZIS NSs) via a two-step in situ growth method on FTO glass to acquire a sufficient interfacial contact between two semiconductors. Based on their electronic band structures, the CdS is designed to be firstly grown on FTO to act as a photoelectron transport layer and 2D ZIS is further fabricated on the CdS as a photohole accumulation layer to directly contact the electrolyte. Benefitting from the Type II band alignment between the CdS and ZIS, such a heterostructure significantly enhances the separation efficiency and prolongs the lifetime of photocarriers. More importantly, it ensures that photoholes accumulate on the 2D ZIS with a highly exposed surface area for an oxidation reaction at the surface-active sites, while the photoelectrons transfer to counter electrode for hydrogen evolution. The optimum CdS@ZIS heterostructure photoanode exhibits a superior PEC performance with a photocurrent of 4.19 mA/cm2 at 1.23 VRHE (two times that of the CdS and eight times that of ZIS) and an applied bias photo-to-current efficiency (ABPE) of 1.93% at 0.49 VRHE. This work can inspire the future design of heterostructure photoanodes for highly efficient solar energy conversion. [ABSTRACT FROM AUTHOR]

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Background and Objectives: The use of two-dimensional materials in the photodetector fabrication has received much attention in recent years. Graphene is a two-dimensional material that has been extensively researched to make photodetectors. The responsivity of graphene photodetectors was limited by the low optical absorption in graphene (~2.3% for single layer graphene). Therefore, graphene along with other materials has been used to fabricate a photodetector with the desired properties. The graphene is used for the improvement of the silicide platinum photodetector. Methods: The platinum silicide photodetector with graphene has been experimentally fabricated and characterized, and all steps of the device fabrication and the characterization are completely provided in addition to required equations for device analysis is completely provided. A graphene layer is transferred on the platinum silicide layer, and the graphene layer creates the photoconductor gain in the platinum silicide photodetector. Results: In the proposed device, near-infrared light is detected in the platinum silicide, and by placing a layer of graphene on the platinum silicide, the optical current and responsivity increase compared to the platinum silicide photodetector without graphene. Experimental results show that the optical current, external quantum efficiency, and responsivity increase in the platinum silicide photodetector with graphene. The graphene not only functions as the charge transport channel, but also works as a photoconductor. Conclusion: The optical current and responsivity are increased by the platinum silicide photodetector with graphene. In our photodetector, the highest responsivity is 120 mA/w in the 1310 nm wavelength, and the optical current is 100 nA at the applied voltage of 8 V. Our photodetector has optical current, responsivity, and external quantum efficiency twice as much as platinum silicide photodetector. Experimental results show the good performance of graphene with platinum silicide photodetector. [ABSTRACT FROM AUTHOR]

[Display omitted] • Negative formation energies, positive phonon modes, and AIMD simulations confirm the stability of the MLs and the heterostructure. • SnS/GeSe heterostructure exhibits a direct band gap, indicating that this system can be used in optical devices. • A smooth paraelectric-ferroelectric phase transition in SnS/GeSe, is explained by phonon dispersions and Landau theory. • Our results indicate that the spontaneous polarization of the SnS/GeSe construct can be controlled via in-plane strains. Low-dimensional layered ferroelectric van der Waals heterostructures (vdWHs) are of tremendous interest for novel nanoscale electronic applications, including nonvolatile memories, transistors, and sensors. Here, we design SnS/GeSe multilayer vdWHs and show that the construct is ferroelectric with a spontaneous polarization of 3.71 × 10-10 Cm−1. We computationally analyze SnS and GeSe monolayers (MLs) and SnS/GeSe heterostructures using density functional theory (DFT) with van der Waals (vdW) correlations. Specifically, we determine structural parameters, formation energies, polarization, and phonon modes. Negative formation energies with real frequencies of phonon spectra confirm the (relative) stabilities of SnS and GeSe monolayers (MLs) and SnS/GeSe heterostructures. The electronic properties of both monolayers are retained in the SnS/GeSe construct, which exhibits a direct band gap with a value of 1.13 eV. The calculations of phonon spectra and double-well potential of monolayers unveil a Pnm21 ferroelectric – Pnmm paraelectric phase transformation. The SnS/GeSe multilayer shows the largest spontaneous polarization of 3.71 × 10-10 Cm−1 compared to 2.78 × 10-10 Cm−1 and 3.69 × 10-10 Cm−1 for SnS- and GeSe-MLs, respectively. Additionally, we demonstrate that the spontaneous polarization, band gap, dynamic stability, and band gap types of SnS/GeSe heterostructures can be tuned through the application of biaxial strains. For an in-plane 5 % tensile strain, SnS/GeSe has a spontaneous polarization of 3.90 × 10-10 Cm−1. The band gap of the SnS/GeSe heterostructure widens with increasing tensile biaxial strain, maintaining its characteristics as a direct band gap semiconductor up to 2 % tensile strain. These findings demonstrate that SnS/GeSe heterostructures are promising materials with significant potential for applications in nanoelectronics. [ABSTRACT FROM AUTHOR]

Determining suitable anode materials is crucial in the advancement of lithium-ion and sodium-ion battery technologies. We propose that the two-dimensional (2D) material Cu 2 N holds promise as a viable anode candidate. The Cu 2 N monolayer exhibits a stable checkerboard lattice crystal structure, ensuring structural integrity. Its excellent metallic electronic structure facilitates efficient conductivity during battery operation. We have observed that Li/Na ions can chemically bond to Cu 2 N substrates via specific charge exchange mechanisms. Moreover, the Cu 2 N monolayer demonstrates favorable wettability and compatibility with common electrolytes used in lithium-ion and sodium-ion batteries, including solvent molecules and metal salts. Our findings indicate that the Li/Na storage capacity of the Cu 2 N monolayer reaches approximately 760/760 mAh/g, surpassing that of graphite anodes significantly. Notably, the Li/Na diffusion barrier on the Cu 2 N monolayer is merely 5/13 meV, lower than that of most other 2D anode materials. Our results underscore the potential of the Cu 2 N monolayer as an outstanding electrode material, offering high storage capacity, rapid charge/discharge rates, and favorable wettability with electrolytes. • The Cu 2 N monolayer has a tessellated lattice structure with good topological properties. • The Cu 2 N monolayer has good wettability with common electrolyte solutions. • The Cu 2 N monolayer can stably adsorb Li and Na ions and has good electrical conductivity before and after adsorption. • The Cu 2 N monolayer has a high storage capacity and a low diffusion barrier. • The open-circuit voltage of Cu 2 N monolayer as anode material is also in the ideal range. [ABSTRACT FROM AUTHOR]

Plant cell wall polysaccharides are notoriously difficult to analyze, and most methods require expensive equipment, skilled operators, and large amounts of purified material. Here, we describe a simple method for gaining detailed polysaccharide structural information, including resolution of structural isomers. For polysaccharide analysis by gel electrophoresis (PACE), plant cell wall material is hydrolyzed with glycosyl hydrolases specific to the polysaccharide of interest (e.g., mannanases for mannan). Large format polyacrylamide gels are then used to separate the released oligosaccharides, which have been fluorescently labeled. Gels can be visualized with a modified gel imaging system (see Table of Materials). The resulting oligosaccharide fingerprint can either be compared qualitatively or, with replication, quantitatively. Linkage and branching information can be established using additional glycosyl hydrolases (e.g., mannosidases and galactosidases). Whilst this protocol describes a method for analyzing glucomannan structure, it can be applied to any polysaccharide for which characterized glycosyl hydrolases exist. Alternatively, it can be used to characterize novel glycosyl hydrolases using defined polysaccharide substrates.

A Ruddlesden-Popper (RP) type structure is well-known in oxide perovskites and is related to many interesting properties such as superconductivity and ferroelectricity. However, the RP phase has not yet been discovered in inorganic halide perovskites. Here, we report the direct observation of unusual structure in two-dimensional CsPbBr3 nanosheets which could be interpreted as the RP phase based on model simulations. Structural details of the plausible RP domains and domain boundaries between the RP and conventional perovskite phases have been revealed on the atomic level using aberration-corrected scanning transmission electron microscopy. The finding marks a major advance toward future inorganic halide RP phase synthesis and theoretical modeling, as well as unraveling their structure-property relationship.

Synopsis: A case of open spina bifida with brain anomalies diagnosed using three‐dimensional ultrasound in the first trimester. [ABSTRACT FROM AUTHOR]

In this paper, the heat transfer and ablation thermal insulators in solid rocket motor are investigated. Therefore, by collecting and solving the thermal ablation equations, a computer program, using MATLAB software, is developed which can predict the thermal response of insulators in different operating conditions and compare the performance of these insulators. The heat and mass transfer equations are considered in two dimensions in a solid body. We used the equations, finite volume method with implicit formulation for time dependency to solve equations. The reaction equation which written in the form of Arrhenius, is solved using Runge-Kutta method, and the density and the flux of the gas produced at each step are obtained. Also we represent a model for the rate of recession.

Iron(II)-based metal organic framework (Fe(II)-MOF) nanosheets have emerged as promising candidates for photo-Fenton catalysis. However, efficiently synthesizing Fe(II)-MOF nanosheets remains a significant challenge. Here, a bottom-up synthesis strategy is proposed to prepare two-dimensional Fe-MOF nanosheets (TFMN) with micrometer lateral dimensions and nanometer thickness, featuring Fe(II) as the metal nodes. The application of TFMN in the photo-Fenton degradation of carbamazepine (CBZ) demonstrates remarkable CBZ degradation performance and excellent efficiency across a wide range of pH values. The electron density and density of states are further calculated by density functional theory. Mechanism analysis identifies h+, •OH and •O 2 − as the predominant active species contributing to the catalytic oxidation process in the Vis/TFMN/H 2 O 2 system. [Display omitted] • TFMN were synthesized for the first time by a simple solvent thermal method. • The suitability of the method in synthesizing various MOF nanosheets was explored. • TFMN exhibited outstanding activity in photocatalytic degradation of pollutants. • The electron transfer direction and density of states of TFMN were calculated. [ABSTRACT FROM AUTHOR]

[Display omitted] • The 2D superlattice heterostructure VOGO-11 was fabricated using an interface modulation strategy via electrostatic-interaction-driven self-assembly. • The hierarchical design enabled the full exposure of accessible adsorption sites and realized the restrained dissolution. • VOGO-11 exhibited broad working pH range and excellent adsorption capacity for Nd, Dy, and Lu exceeding 600 mg/g. • Environment application assessment demonstrated the practical application potential of VOGO-11. Effective recovery of rare earth elements from wastewater is crucial for the modern industry, as well as for protecting the human health and ecosystem. Nevertheless, it is still challenging to realize efficient and selective low-concentration rare earth extraction in systems containing high levels competing metal ions. Here, we report on the fabrication of two-dimensional superlattice heterostructures (VOGO-x) through the alternating restacking of VOPO 4 nanosheets and GO-PDDA nanosheets via electrostatic self-assembly. The meticulously organized molecular scale of superlattice heterostructures enable the full exposure of accessible adsorption sites and facilitate the transport of rare earth ions, meanwhile the abundant oxygen-containing phosphate groups within the interlayer can realize selective rare earth ions extraction. Furthermore, the tunable interlayer interaction can promote structure stability to prevent dissolution. Consequently, VOGO-11 possesses excellent rare earth adsorption performance, with a saturated adsorption capacity (Nd(III) 631.52 mg/g, Dy(III) 689.48 mg/g, Lu(III) 716.06 mg/g), high utilization rate of adsorption sites and short adsorption equilibrium time of simply 10 min in the REE aqueous solution. Furthermore, VOGO-11 exhibits outstanding selective rare earth adsorption ability over a wide range of metal ions in the low-concentration simulated wastewater and actual leaching tailings. These results demonstrate the material's promising potential in capturing rare earth ions and pave the way to the development of two-dimensional superlattice heterostructures through interface modulation for effective rare earth extraction. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) organic-inorganic hybrid perovskites have emerged as promising candidates for photocatalytic hydrogen production due to their unique optoelectronic properties. However, the organic cations in the interlayer of 2D perovskites generally retard the internal charge transfer due to the large interlayer van der Waals barrier for electron transfer, which defines the imperative to engineering the organic entity. Herein, taking phenethylammonium lead iodide (PEA 2 PbI 4) as a typical example, we show that by substituting the hydrogen with fluorine atom in the para-position of the phenyl group, the internal electron transfer was promoted remarkably. The improved electron transfer is ascribed to the introduction of fluorine with strong electronegativity, which leads to interlayer polarization and almost zero-potential barrier between the organic layers. Consequently, 4-FPEA 2 PbI 4 exhibits ca. 8.2 times higher photocatalytic H 2 evolution activity than PEA 2 PbI 4. This work establishes a paradigm for optimizing the photocatalytic properties of 2D hybrid perovskites by engineering the organic cations. [Display omitted] • The F substitution for H in the organic cations modified the geometry of PEA 2 PbI 4. • The F substitution introduced strong interlayer polarization in PEA 2 PbI 4. • The F substitution reduced the electron potential barrier between the organic layers. • The F substitution for H boosts the internal electron transfer of PEA 2 PbI 4. • The photocatalytic activity of 4-FPEA 2 PbI 4 is 9.2 times that of PEA 2 PbI 4. [ABSTRACT FROM AUTHOR]

Janus materials possess extraordinary physical, chemical, and mechanical properties caused by symmetry breaking. Here, the mechanic properties, electronic structure, magnetic properties, and optical properties of Janus Cr 2 TeX (X= P, As, Sb) monolayers are systematically investigated by the density functional theory. Janus Cr 2 TeP, Cr 2 TeAs, and Cr 2 TeSb are intrinsic ferromagnetic (FM) half-metals with wide band gaps between spin-down channel and half-metallic gaps. The Curie temperature (T c) of these monolayers are about 583, 608, and 597 K, respectively by Monte Carlo simulations based on the Heisenberg model. Additionally, it has been found that Cr 2 TeX (X= P, As, Sb) monolayers still exhibit FM half-metallic properties under biaxial strain ranging from −6% to 6%. At last, the Cr 2 TeP monolayer has a higher absorption coefficient than the Cr 2 TeAs and Cr 2 TeSb monolayers in the visible region. The results predict that Janus Cr 2 TeX (X= P, As, Sb) monolayers with novel properties have good potential for applications in future nanodevices. • Janus Cr 2 TeP, Cr 2 TeAs, and Cr 2 TeSb are intrinsic ferromagnetic (FM) half-metals with wide band gaps between spin-down channel and half-metallic gaps. • The Curie temperature of these monolayers are about 583, 608, and 597 K, respectively by Monte Carlo simulations based on the Heisenberg model. • Cr 2 TeX (X= P, As, Sb) monolayers still exhibit FM half-metallic properties under biaxial strain ranging from −6% to 6%. • The Cr 2 TeP monolayer has a higher absorption coefficient than the Cr 2 TeAs and Cr 2 TeSb monolayers in the visible region. [ABSTRACT FROM AUTHOR]

The search for new two-dimensional (2D) carbon nitride (CN) materials with desirable properties is an important and critical area of research. This study presents a series of 2D CN materials with appealing features such as semimetal or flat bands. By utilizing group theory and graph theory, we perform a random search of the configurational space of 2D CN monolayers, leading to the identification of 721 new CN materials. Extensive density functional theory calculations were then conducted to evaluate their properties. We found that 57 materials exhibit semimetal behavior, while 664 display characteristics of semiconductors and normal metals. Notably, materials such as 51-5-16-C 3 N-r568 and 55-5-20-C 4 N-r568 feature topological Dirac semimetals with protected 1D topological boundary states. Moreover, 31 materials possess flat bands near their Fermi level, including two with kagome-like flat bands that induce intrinsic spontaneous magnetization due to partially-occupied flat bands. Our results offer several promising candidates for exploring physical phenomena related to semimetals or flat bands in 2D CN materials. [Display omitted] [ABSTRACT FROM AUTHOR]