Candidate For Many Applications Research Articles

Electronic, Optical and Thermoelectric Properties of Two-Dimensional Molybdenum Carbon Mo2C-MXenes

We investigate the structural, electronic, optical, and thermoelectric properties of three compositions of Mo2C-MXenes (Mo2CF2, Mo2C(OH)2, and Mo2CO2) from monolayer to multilayer by first principles calculation within Density Functional Theory (DFT) and Boltzmann transport theory. Firstly, the atomic structures of Mo2C-MXenes are optimized, and their respective structures are created with comparative research. Secondly, their electronic band structures and optical properties are studied in detail. The estimation of the bandgap energy of Mo2C-MXenes with its functionalization reveal that most Mo2CF2 and Mo2C(OH)2 layers are semiconductors, while Mo2CO2 behaves as a metal. The electrical and optical properties can be altered by controlling the on-surface functional groups and the number of layers. Computation of the thermoelectric (TE) properties of Mo2C-MXenes reveals that, upon heating to 600 K, Mo2CF2 and Mo2C(OH)2 exhibit a high Seebeck coefficient and a relatively high electrical conductivity. The Seebeck coefficient reaches ~400 µV K−1 at room temperature for all layers of Mo2CF2 MXenes. Our results prove that Mo2CF2 is considered a promising material for thermoelectric devices, while Mo2CO2 does not possess better thermoelectric performance. Mo2C-MXenes from monolayer to multilayer have outstanding properties, such as flexible bandgap energy and high thermal stability, making them promising candidates for many applications, including energy storage and electrode applications.

Microstructure and mechanical behavior of TaxHf1−xC–SiC fabricated by reactive hot‐pressing: Effect of Ta:Hf ratio

AbstractTaxHf1–xC are promising candidates for many applications under harsh environments due to their unique properties. Up until now, low‐temperature densification is still a big challenge for these ceramics. Moreover, the effect of Ta:Hf ratio on microstructure development and mechanical behavior of the ceramics is not clear. In this work, highly dense TaxHf1−xC–SiC ceramics (x = 0.2, 0.4, 0.6, 0.8) were fabricated at 1700°C by a novel reactive hot‐pressing processing with 8 wt% Si as sintering aid, which present excellent mechanical properties. Fracture toughness of the ceramics is higher than 6.3 MPa·m1/2, with the highest toughness achieved in Ta0.6Hf0.4C–SiC (8.5 MPa·m1/2). With the increase of Ta content, hardness of the ceramics tends to increase, while the bending strength tends to decrease. The highest bending strength is achieved in Ta0.2Hf0.8C–SiC (637 MPa), and the highest hardness is achieved in Ta0.8Hf0.2C–SiC (17.6 GPa). This work lays the foundation for the composition design of TaxHf1−xC‐based ceramics and composites.

High-Brightness Blue Polariton Organic Light-Emitting Diodes.

Polariton organic light-emitting diodes (POLEDs) use strong light-matter coupling as an additional degree of freedom to tailor device characteristics, thus making them ideal candidates for many applications, such as room temperature laser diodes and high-color purity displays. However, achieving efficient formation of and emission from exciton-polaritons in an electrically driven device remains challenging due to the need for strong absorption, which often induces significant nonradiative recombination. Here, we investigate a novel POLED architecture to achieve polariton formation and high-brightness light emission. We utilize the blue-fluorescent emitter material 4,4'-Bis(4-(9H-carbazol-9-yl)styryl)biphenyl (BSBCz), which exhibits strong absorption and a highly horizontal transition-dipole orientation as well as a high photoluminescence quantum efficiency, even at high doping concentrations. We achieve a peak luminance of over 20,000 cd/m2 and external quantum efficiencies of more than 2%. To the best of our knowledge, these values represent the highest reported so far for electrically driven polariton emission from an organic semiconductor emitting in the blue region of the spectrum. Our work therefore paves the way for a new generation of efficient and powerful optoelectronic devices based on POLEDs.

Soft Optical Waveguides for Biomedical Applications, Wearable Devices, and Soft Robotics: A Review

In the domains of biomedical applications, wearable devices, and soft robotics, recent advancements have underscored the potential of soft, stretchable, and biocompatible devices. The design of optical soft devices has emerged as an ideal candidate for many applications owing to their high flexibility and immunity to electromagnetic interference. In this review, recent advances in soft optical waveguides, including advanced material selection, fabrication strategies, and characterization, are discussed. Herein, a comprehensive summary of the soft‐waveguide sensing strategies and actuation approaches are provided. Furthermore, the extensive applications of soft optical waveguides in the fields of biomedicine, wearable devices, and soft robotics are explored. Lastly, the challenges and opportunities for the future of soft optical waveguides, including multimodal sensing, algorithm optimization, and manufacturing scalability, are discussed.

Metal oxide stabilized zirconia modified bio-derived carbon nanosheets as efficient electrocatalysts for oxygen evolution reaction

Zirconia is a promising candidate for many applications, especially when stabilized with metal oxide nanoparticles such as yttria and ceria. Zirconium oxide-based materials supported on carbon nanomaterials have shown excellent performance electrocatalysts due to their outstanding catalytic activities and high stability. In this work, a one-pot hydrothermal method was used to prepare porous stabilized zirconia nanoparticles with yttria and ceria (YSZ and CSZ) anchored on carbon nanosheets derived from molasses fiber waste as a sustainable source and annealing at various temperatures (MCNSs). The prepared composites YSZ/MCNSs and CSZ/MCNSs exhibit superior oxygen evolution reaction performance in alkaline medium. Various physicochemical analysis techniques such as SEM, EDX, HR-TEM, BET, XRD and XPS are employed to characterize the designed catalysts. The results showed that the doping of molasses fibers exfoliated into 2D nanosheets controlled the growth of the YSZ particles into the nanosize and increased their crystallinity. This improves the electrochemical surface area and stability, and modulates the electronic structure of zirconium, yttrium and cerium which facilitate the adsorption of OH− ions, and all contribute to the higher catalytic activity.Graphical

A Wideband Circularly Polarized Magnetoelectric Dipole Transmitarray Antenna Based on Element Rotation Techniques

In this article, a wideband circularly polarized (CP) transmitarray antenna (TA) operating at the X-band is reported. A receive-and-transmit type anisotropic magneto-electric (ME) dipole is proposed as the broadband TA unit cell with low-insertion-loss characteristic. By employing the element rotation methodology, the continuous transmissive phase compensation is achieved, thus producing the high-gain directive radiation. The 16×16-element CP TA implemented using the designed ME-dipole structure not only possesses wide measured 1-dB and 3-dB gain bandwidths of 24.5% (10.75-13.75 GHz) and 33.3% (10-14 GHz), respectively, but also yields a notable 1.5-dB axial ratio (AR) bandwidth of 37.4% (9.25-13.5 GHz). Peak gain of 24.3 dBic and aperture efficiency of 46% are experimentally measured. The proposed CP TA shows attractive advantages including wide bandwidth, high-purity circular polarization and stable gain, which makes it a competitive candidate for many applications including satellite communication (SatCom).

Enhanced spectral density of a single germanium vacancy center in a nanodiamond by cavity integration

Color centers in diamond, among them the negatively charged germanium vacancy (GeV−), are promising candidates for many applications of quantum optics, such as a quantum network. For efficient implementation, the optical transitions need to be coupled to a single optical mode. Here, we demonstrate the transfer of a nanodiamond containing a single ingrown GeV− center with excellent optical properties to an open Fabry–Pérot microcavity by nanomanipulation utilizing an atomic force microscope. Coupling of the GeV− defect to the cavity mode is achieved, while the optical resonator maintains a high finesse of F=7700, and a 48-fold spectral density enhancement is observed. This article demonstrates the integration of a GeV− defect with a Fabry–Pérot microcavity under ambient conditions with the potential to extend the experiments to cryogenic temperatures toward an efficient spin-photon platform.

Enhanced Hall mobility in graphene-on-electronic-grade diamond

The outstanding electronic properties of graphene make this material a candidate for many applications, for instance, ultra-fast transistors. However, self-heating and especially the detrimental influence of available supporting substrates have impeded progress in this field. In this study, we fabricate graphene-diamond heterostructures by transferring graphene to an ultra-pure single-crystalline diamond substrate. Hall-effect measurements were conducted at 80 to 300 K on graphene Hall bars to investigate the charge transport properties in these devices. Enhanced hole mobility of 2750 cm2 V−1 s−1 could be observed at room-temperature when using diamond with reduced nitrogen (Ns0) impurity concentration. In addition, by electrostatically varying the carrier concentration, an upper limit for mobility is determined in the devices. The results are promising for enabling carbon–carbon (C-C) devices for room-temperature applications.

A Versatile Supramolecular Assembly Platform for Tumor Microenvironment Motivated Drug Release and Ferroptosis Synergistic Therapy.

We report a simplistic approach that employs complexation between poly(N-allylglycine) modified with 3-mercaptoacetic acid (PNAG-COOH) and a series of metal ions to construct a new type of supramolecular architecture with intriguing features that enable a versatile and advanced nanoplatform. In most cases, such complexation results in nanoscale vesicles with superior stability, which differs significantly from the precipitates of conventional carbon-chain polymers and polypeptides. We attribute this to the polar tertiary amide groups in the polypeptoid backbone that offer excellent water affinity and numerous noncovalent molecular interactions. Particularly, the PNAG-COOH/Fe2+ complex can generate reactive oxygen species via a Fenton reaction in the presence of H2O2, thus causing ferroptosis selectively in the tumor cell. In addition, a H2O2-modulated intracellular in situ morphology transition enables prompt release of doxorubicin, representing a synergistic target antitumor efficacy. The prepared supramolecular platforms present promising candidates for many applications, considering the ability to assemble with various metal ions.

Preparation and Magneto-Structural Investigation of High-Ordered (L21 Structure) Co2MnGe Microwires

We used the Taylor–Ulitovsky technique to prepare nanocrystalline Co2MnGe Heusler alloy glass-coated microwires with a metallic nucleus diameter of 18 ± 0.1 µm and a total diameter of 27.2 ± 0.1 µm. Magnetic and structural studies were carried out to determine the fundamental magneto-structural characteristics of Co2MnGe glass-coated microwires. XRD revealed a well-defined nanocrystalline structure with an average grain size of about 63 nm, lattice parameter a = 5.62 and a unique mixture of L21 and B2 phases. The hysteresis loops measured at different temperatures indicated a well-known ferromagnetic behavior for the reduced remanent, where a monotonic increasing in the reduced remanent and saturation magnetization occurs. The coercivity shows anomalous behavior compared to the Co2Mn-based glass-coated microwires. The magnetization curves for field cooling and field heating (FC–FH) demonstrate a considerable dependence on the applied magnetic field, ranging from 50 Oe to 20 kOe. Internal stresses, originated by the production process, resulted in various magnetic phases, which were responsible for the notable difference of FC and FH curves on magnetization dependence versus temperature. Furthermore, the ferromagnetic behavior and expected high Curie temperature, together with high degree of the L21 order, make it a promising candidate for many applications.

Powder Metallurgy Processing and Characterization of the χ Phase Containing Multicomponent Al-Cr-Fe-Mn-Mo Alloy

High entropy alloys present many promising properties, such as high hardness or thermal stability, and can be candidates for many applications. Powder metallurgy techniques enable the production of bulk alloys with fine microstructures. This study aimed to investigate powder metallurgy preparation, i.e., mechanical alloying and sintering, non-equiatomic high entropy alloy from the Al-Cr-Fe-Mn-Mo system. The structural and microstructural investigations were performed on powders and the bulk sample. The indentation was carried out on the bulk sample. The mechanically alloyed powder consists of two bcc phases, one of which is significantly predominant. The annealed powder and the sample sintered at 950 °C for 1 h consist of a predominantly bcc phase (71 ± 2 vol.%), an intermetallic χ phase (26 ± 2 vol.%), and a small volume fraction of multielement carbides—M6C and M23C6. The presence of carbides results from carbon contamination from the balls and vial during mechanical alloying and the graphite die during sintering. The density of the sintered sample is 6.71 g/cm3 (98.4% relative density). The alloy presents a very high hardness of 948 ± 34 HV1N and Young’s modulus of 245 ± 8 GPa. This study showed the possibility of preparing ultra-hard multicomponent material reinforced by the intermetallic χ phase. The research on this system presented new knowledge on phase formation in multicomponent systems. Moreover, strengthening the solid solution matrix via hard intermetallic phases could be interesting for many industrial applications.

Sc2CX (X=N2, ON, O2) MXenes as a promising anode material: A first-principles study

MXenes’ tunable properties make them excellent candidates for many applications in future nanoelectronics. In this work, we explore the suitability of Sc2CX (X=N2, ON, O2) MXenes to act as the active anode materials in Na-ion based batteries (NIBs) by means of ab initio simulations. After analyzing the structural and elastic properties of all the possible models to evaluate the energetically favorable N and O functionalization sites, our calculations show that both Sc2CON and Sc2CN2 present a clear metallic character, making them potential candidates as anode materials. The investigation of the most relevant features for anode performance, such as the adsorption and diffusion of Na atoms, the intrinsic capacity, the open circuit voltage, and the storage capacity, shows that both systems are serious alternatives to the most common 2D materials currently employed in alkali metal batteries. In particular, Sc2CN2 presents better diffusion behavior thanks to the absence of Na clustering on its surface, with optimal diffusion barriers comparable to other 2D materials, such as MoN2, while the values of diffusion barriers for Sc2CON are at least three times smaller than those found for other anode candidates. Similarly, while the capacity of Sc2CON is close to the one reported for 2D Sc2C, Sc2CN2 possesses a power density more than twice higher than the ones of 2D materials, such as Sc2C, graphite, and MoS2. Our results, thus, confirm the urge for further experimental exploration of the MXene Sc2CX (X=N2, ON, O2) family as anode material in NIBs.

A Correlation Coefficient Sparsity Adaptive Matching Pursuit Algorithm

This paper presents a correlation coefficient sparsity adaptive matching pursuit (CCSAMP) algorithm for practical compressed sensing (CS). The sparsity adaptive matching pursuit (SAMP) has been enhanced using the CCSAMP algorithm. The CCSAMP's capacity to accurately reconstruct the signal with fewer repetitions is its most novel characteristic when compared to other state-of-the-art SAMP enhancement methods. This makes it a candidate for many practical applications that need fast reconstruction. The proposed algorithm constructs two correlation vectors, which represent the input signals recovered from the support set and candidate set. The step size is transformed by their Pearson correlation coefficients (PCCS). Compared to the residual energy, the correlation coefficient is more sensitive. The CCSAMP reduces the number of iterations while maintaining the SAMP's capability of signal reconstruction without prior knowledge of the sparsity. Simulation shows that the CCSAMP can significantly reduce the number of iterations compared to the SAMP algorithm. The CCSAMP can be used for radar detection, radar 3D imaging, and other fields where fast and accurate reconstruction of signals is required.

A review on MWCNTS: the effect of its addition on the polymer matrix

In recent years, it has been realized that nanocomposite materials are candidates for many applications in all fields due to their unique properties. This review aims to study the possibility of modifying some properties of polymers by adding carbon nanotubes to improve their properties by taking advantage of the large surface area of MWCNTs to volume ratio. For this purpose, multi-walled carbon nanotubes were used at different ratios and by different mixing methods. Then the effect of this addition was monitored by the procedure of some mechanical, electrical and thermal measurements of the resulting nanocomposite materials. The results of the tests showed that the quality of the filling depends on the way it is distributed within the polymer matrix, where the homogeneous dispersion of MWCNTs will reflect on the properties of the nanocomposite material thus benefit from the special properties of it. Also, the results showed that the addition of MWCNTs at low ratios achieved uniform distribution and dispersion, so improved the properties of the materials such as tensile strength, elongation at break and young's modulus. The ratio of 0.5 wt % of MWCNTs represented an average value for adding MWCNTs to various types of polymers. These composite nanomaterials can replace other industrial materials in many applications.

MULTIFREQUENCY STACKED PATCH ANTENNA ANALYSIS

In this paper, the theoretical and simulated results of a quad-band patch antenna without any air/foam gap between the dielectric layers are discussed. The design idea uses a skated dielectric layers to achieve a multi-frequency operation. The antenna under study includes four patches patterned on the top of layered dielectric substrates and is stacked vertically. Two pairs of spaced slits are embedded at the patch's radiation edges of the bottom and second patches to adjust the resonant frequencies. The resonant frequencies of the different patches are obtained at 4 GHz, 5 GHz, 6 GHz, and 7 GHz. According to the cavity theory and equivalent circuit approach, a theoretical model of the multilayer stacked patch antenna (MLSPA) is determined. Theoretical and simulated return loss plot is presented to validate the proposed design. The antenna parameters such as radiation pattern, gain, voltage standing wave ratio (VSWR), and beam-width are also discussed. Good impedance matching and radiation characteristics at the four operating bands make this antenna a good candidate for many applications. The antenna simulations are performed using a high frequency structure simulator (HFSS) 15.0 tool.

Potential of MXenes as a novel material for spintronic devices: a review.

The search for materials for next-generation spintronic applications has witnessed exponentially increasing interest, mainly due to the explosive development of numerous two-dimensional (2D) materials discovered in the last decade. Among them, MXenes have emerged as promising candidates for many applications due to their unique and versatile tunability in structure and properties. In particular, their excellent combination of conductivity and highly charged surfaces leads to outstanding electrochemical properties that are significant in electronic applications. Moreover, the ease of modifying the atomic and electronic structures, and thus the functionalities of MXenes, further opens up the opportunity to realize MXenes-based spintronic device applications. The explosive development of MXenes, such as tuning the bandgap and enhancing their magnetic properties, could pave the way for the integration of MXenes in device configurations suitable for spintronics. In this article, we provide an overview of the potential applications of MXenes with a special focus on spintronic device applications. We commence the discussion with various fundamental aspects of spintronics, including the understanding of materials for spintronics in general, MXenes, and their fabrication, followed by presenting perspectives on plausible strategies and future challenges in integrating MXenes into spintronic devices.

Minimizing Deployment Cost for Vehicular Sensor Networks in Air Monitoring Applications

The vehicular sensor network (VSN) is a bright candidate for many applications owing to its particular advantages. Such an application is air pollution monitoring, a critical issue associated directly with public health. We also notice that public transports are well-suited to deploy the network for this type of application. In this article, we propose a practical approach that leverages public buses to build the vehicle network with attached sensors for air pollution monitoring toward minimizing the deployment cost. Therefore, we hereafter call this problem vehicular sensor deployment (VSD). We first convert the VSD issue to a flow network described by a directed graph. Then, based on air sampling requirements, capacity constraints, and flow conservation of the flow network, we formulate the problem as an integer linear programming (ILP) model that yields the optimal solution. In addition, we suggest an approximation algorithm implemented by the linear programming relaxation technique combined with the randomized rounding algorithm (LPR-RRA), which provides approximate solutions to large-scale VSD problems. We also propose a greedy-based algorithm (GBA) to solve the problem against the most effective sampling in each iteration. Finally, we conduct experiments to evaluate the performance of the proposed algorithms as well as the influences of associated factors on the deployment cost. Simulation results show that the approximation algorithm approaches the optimal and outperforms the greedy.

Laser powder bed fusion of titanium aluminides using sequential thermal scanning strategy

Titanium Aluminides (TiAls) are good candidates for many applications in the automobile, aerospace, and energy industry because of their high strength, toughness, corrosion, and oxidation resistance at high temperatures. Nevertheless, the low ductility and fracture toughness makes processing of TiAls extremely difficult. Laser powder bed fusion (L-PBF) can additively manufacture high-quality components of various materials. The micro layer-based nature of this process allows for design freedom and near-net shape products. The rapid cooling rates during the L-PBF process may cause defects during the manufacturing of hard materials such as TiAls. These rapid cooling rates lead to high induced residual stresses and crack formation. Several heating strategies and post-heat treatments methods are presented in the open literature for reducing the cracks formed during the L-PBF of TiAl. This study presents a new, novel scanning strategy for mitigating the cracks and reducing residual stresses in the L-PBF of Ti-48Al-2Cr-2Nb. This scanning strategy, referred to as sequential thermal scanning (STS) strategy, applies three thermal cycles in each layer: pre-heating selective area of the powder, melting a layer of powder, and post-heating the solidified layer. The laser process parameters used in each step of the STS strategy were determined and explained in this study. The thermal cycles applied in this scanning strategy were verified using an infra-red thermal camera. Sets of process parameters were studied in the melting step of the STS strategy using a factorial design of experiments. These sets of process parameters cover a large range of volumetric energy density (17–2917 J/mm3). The powder morphology, composition, and behavior were studied. The TiAl fabricated parts were investigated for bulk density, surface and internal cracks, balling defects, internal pores, and surface quality. The spatter formation was studied using a high speed camera. Process maps for the relationship between the laser process parameters and part defects were formulated. Residual stresses were measured to understand the influence of the STS strategy and its effects on the surface features and cracks. The results showed that the STS strategy could be used to produce parts of approximately 99 % density without internal pores. In addition, the STS strategy minimized the amount of internal micro-cracks in TiAl parts. This study contributes to the mitigation of internal defects in the L-PBF of TiAl using a sequential thermal scanning (STS) strategy.

Polyglycerols as Multi-Functional Platforms: Synthesis and Biomedical Applications.

The remarkable and unique characteristics of polyglycerols (PG) have made them an attractive candidate for many applications in the biomedical and pharmaceutical fields. The presence of multiple hydroxy groups on the flexible polyether backbone not only enables the further modification of the PG structure but also makes the polymer highly water-soluble and results in excellent biocompatibility. In this review, the polymerization routes leading to PG with different architectures are discussed. Moreover, we discuss the role of these polymers in different biomedical applications such as drug delivery systems, protein conjugation, and surface modification.

Nitrogen-doped porous carbons derived from sustainable biomass via a facile post-treatment nitrogen doping strategy: Efficient CO2 capture and DRM

Nitrogen (N)-doped carbon materials have become promising candidates for many applications. In this paper, the biomass activated carbon (BC) was obtained by carbonization and activation of soybean meal. Using soybean meal as the precursor, potassium hydroxide (KOH) as the activator and melamine as the nitrogen source, a series of N-doped porous biomass carbons (H-NC-X) with different N contents were achieved via a facile post-treatment nitrogen doping strategy. Then these samples were used as a catalyst for dry reforming of methane (DRM) reaction and an adsorbent for CO2 capture. Among all the investigated samples, BC has the largest specific surface area and the best pore structure characteristics, showing the best CO2 adsorption capacity. However, when BC was used as a catalyst for DRM reaction, it showed the worst catalytic performance. After nitrogen doping treatment, the CO2 adsorption capacity of the prepared N-doped biomass porous carbon decreased gradually with the increase of the introduced N content. This is mainly due to the destruction of the microporous structure of porous carbon by post-processing nitrogen doping. In contrast, when nitrogen-doped porous carbon was used as the reforming catalyst, the catalytic activity increased with the increase of the introduced N content. The order was: H-NC-30>H-NC-20>H-NC-10. This indicates that when nitrogen-doped porous carbon was used as an adsorbent, the pore structure plays a major role; while when it was used as a reforming catalyst, nitrogen functional groups are the major active sites. This study provides a promising N-doped carbon material for effect CO2 adsorption and DRM reactions.