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Nitrogen oxides (NOx; NO and NO2) are major air pollutants and can cause harmful effects on the human body. Electron Beam Flue Gas Treatment (EBFGT) is a technology that generates electrons with an energy of 0.5–1 MeV using electron accelerators and effectively processes exhaust gases. In this study, NOx was removed using an electron beam accelerator with spraying additives (NaOH and NH4OH). NO and NO2 were 100% and more than 94% removed, respectively, at an electron beam absorbed dose of 20 kGy and an additive concentration of 0.02 M (mol/L). In most cases, NOx was removed better with lower initial NOx concentrations and higher electron beam absorbed doses. As the irradiation strength (mA) of the electron beam increases, the probability of electron impact on the material accordingly rises, which may lead to increase removal efficiency. The results of the present study show that the continuous electron beam process using additives achieved more effective removal efficiency than either individual process (wet-scrubbing or EB irradiation only).

In fuel cell technologies, low-temperature proton exchange membrane fuel cells (LT-PEMFC), high-temperature proton exchange membrane fuel cells (HT- PEMFC), and direct methanol fuel cells (DMFC) are gained significant attention as a promising energy system for practical applications. The developments of cost-effective membrane materials with excellent physicochemical properties are indispensable for replacing the high cost of commercial membranes and achieving the higher performance of fuel cell systems. This review focuses on the developments and modifications of cost-effective poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) as a cation exchange membrane for LT-PEMFC, HT- PEMFC and DMFC. Notably, this review bridges the understanding of PPO based membranes, current advancements, structure, physicochemical properties and fuel cell performances. Progressive developments and a systematic overview of PPO-based membrane developments are explained in detail in terms of functionalization, blend, composite, acid-base, cross-linking, copolymerization, coated and reinforcement. Moreover, the changes in physicochemical properties and fuel cell performances in the membrane are deeply reviewed. Additionally, the utilization of PPO based membranes in different kinds of redox flow battery systems are reviewed. Overall, this review provides an exclusive vision and perspectives to develop the PPO based advanced, cost-effective, and high-performance membranes for fuel cell technologies and redox flow battery systems.

A numerical simulation for a radio frequency (RF) thermal plasma torch was carried out to identify the temperature and velocity distributions and determine the optimal design of a plasma system based on the coil turn and torch inner diameter parameters. Then, the optimized conditions of five coil turns and a torch inner diameter of 64 mm were applied to synthesize titanium boride nanoparticles. The major crystal structure of the synthesized titanium boride nanoparticles was TiB2, with TiB as a minor phase and an average particle size of 42 nm. Subsequently, the gamma-ray shielding performance was analyzed using synthesized titanium boride nanoparticles. Flexible shielding materials were fabricated using a hydrogel to load the synthesized nanoparticles. The attenuation coefficient of the titanium boride nanoparticle flexible material was 0.238 cm−1, and the half-value layer was 2.91 cm.

An in-situ analysis of local strain accommodation on transformation induced plasticity (TRIP) aided multi-phase steel was performed with a correlative application of characterization techniques such as digital image correlation (DIC), electron backscatter diffraction (EBSD), and micro-mechanical testing. The local strain on the complex microstructure of the multi-phase steel was measured during a tensile test using an innovative DIC method (which does not employ artificial patterns), in conjunction with a scanning electron microscope. The constituent phases of the examined surface were identified by postprocessing implemented on the EBSD maps. This was further verified by nano-indentation, consequently enabling systematic and quantitative analyses of the strain partitioning between the phases. Soft acicular ferrite accommodated the largest strain with sites of intense strain localization around the hard, neighboring martensite. The retained austenite transformed gradually into martensite because of the applied strain and caused strain localization in the neighboring acicular ferrite. This verified that DIC method proposed in this study enables precise and effective data collection at the interfaces between different phases that could have certainly been blocked by the DIC patterns in the conventional method.

This work described the structural, morphological, temperature-dependent relative permittivity, and magnetic behavior of nickel ferrite (NiFe2O4) nanoparticles prepared via a facile co-precipitation method. A computational analysis, density functional theory (DFT) calculation was carried out to understand the band structure and density of the state of NiFe2O4. The crystallinity and phase purity was analyzed by powder X-ray diffraction, which confirms the polycrystalline nature of the cubic spinel structure of NiFe2O4 belonging to the Fd3m space group. The calculated crystallite size is about 22 nm. Field emission scanning electron micrograph confirms the agglomerated flake-like grains. All the phonon modes (A1g, Eg and T2g) confirm the inverse spinel cubic structure of NiFe2O4. The dielectric study shows that the relative permittivity is varied between 1.2 × 102 and 1.6 × 103 as a function of different temperature. The obtained semicircle arc from the Cole–Cole plot confirms the grain and grain boundaries contribution in the conduction process. The exploration of the magnetic hysteresis loop measured in the temperature between 5 and 300 K over the field strength of ± 2 T, revealed a ferromagnetic behavior. Temperature-dependent magnetization and coercivity were studied using modified Bloch’s law and Kneller’s law, respectively. The increasing magnetic parameters at low temperature may be due to increasing the surface-spin moment in the finite-size nanoparticles.

Polyethylene glycol (PEG) and glycerol were tested as melt assistants to enhance the melt processability of poly(acrylonitrile-co-1-vinyl imidazole) (co-PAN). The effects of the melt assistants on the molecular mobility of co-PAN were investigated through molecular dynamics (MD) simulations, and the specific volume changes with temperature were analyzed to evaluate the efficiency of the melt assistants theoretically. The MD results demonstrated that both PEG and glycerol increase the specific volume of co-PAN compared to pristine co-PAN. However, the effects of PEG in terms of increasing the specific volume and mobility of co-PAN were superior to those of glycerol. These findings were verified by variations in the shear viscosity of the co-PAN. Spinnability was improved significantly for co-PAN/PEG, and a more uniform co-PAN melt-spun filament could be obtained compared to co-PAN/glycerol. Thus, PEG200 is the best melt assistant for co-PAN, and 15% (w/w) is the optimal content for the melt-spinning of co-PAN.

Helium (He) inductively coupled plasma (ICP) was generated by a right-helical-type RF antenna. At a fixed He pressure of 20 mTorr, the optical emission spectrum from the He plasma was measured with RF power. The E-H mode transition and the characteristic hysteresis of the mode transition were confirmed by a change in the spectral line intensity of the 3 3 D − 2 3 P transition at 587.6 nm. By laser absorption spectroscopy using a laser light with a wavelength of 1083 nm resonant to the 2 3 S → 2 3 P absorption transition, the line-integrated He 2 3 S metastable density was measured and found to show consistent behavior with the spectral line intensity of the 3 3 D − 2 3 P transition during the E-H mode transition. The line-integrated He 2 3 S metastable atom density exhibited distinctly different longitudinal distributions in the E and H modes.

In this study, hybrid inhibitor-doped sol–gels were synthesized using 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT), 3-glycidoxypropyltrimethoxysilane (GPTMS), and tetraethoxysilane (TEOS) at different pH values (4, 7, and 11). The fabricated sol–gels were applied as coatings via a self-assembly method to obtain corrosion resistance for copper substrates in 3.5% NaCl. The AHMT-doped hybrid sol–gel coatings were characterized through different methods. Interactions between the hybrid AHMT-doped sol–gel and copper metal were demonstrated by quantum chemical calculations based on the density functional theory and molecular dynamics simulations. The results from electrochemical impedance spectroscopy and potentiodynamic polarization analysis of the hybrid AHMT-doped sol–gel coating at pH 4 demonstrated enhanced corrosion resistance compared to the data from the tests at pH values of 7 and 11. This can be explained by the formation of an effectively packed layer, which acted as a physical barrier against corrosive chloride ions that protected copper metal against corrosion.

The interface created between an active metal and an oxide support is known to affect the catalytic performance because of the charge transfer process. However, oxide–oxide interfaces produced by s...

A typical metal complex has a central metal surrounded by multiple ligands, which greatly affect the properties of the whole complex. Although heteroleptic complexes often exhibit substantially different behaviors from homoleptic complexes, systematic studies to explain their origins have been rare. Of special importance is to understand why the heteroleptic metal complex shows a more complicated excited state relaxation dynamics than the homoleptic metal complex. To address this issue, we investigated the excited state relaxation dynamics of a heteroleptic Ir(III) complex, fac-Ir(ppy)2(ppz), and two homoleptic Ir(III) complexes, fac-Ir(ppy)3 and fac-Ir(ppz)3, using femtosecond X-ray transient absorption (fs-XTA) spectroscopy, ultrafast optical transient absorption (TA) spectroscopy, and DFT/TDDFT calculation. The data show that the ultrafast relaxation dynamics of ∼450 fs, which is significantly faster than those of previous Ir(III) complexes with other ligands, is observed only in fac-Ir(ppy)2(ppz) but not in the homoleptic Ir(III) complexes. Such dynamics observed for only heteroleptic Ir(III) complexes must originate from the heteroleptic character, and naturally, the inter-ligand energy transfer between two different types of ligands has been suggested to explain the fast dynamics. Both fs-XTA and TA data, however, favor the assignment of the ultrafast dynamics of ∼450 fs to the internal conversion (IC) process from the ppz-localized 3MLCT to the ppy-localized 3MLCT. The DFT/TDDFT calculations support that the abnormally fast IC for fac-Ir(ppy)2(ppz) is due to a large nonadiabatic coupling and the small energy gap between the two states.

Two-dimensional (2D) molybdenum disulfide (MoS2) layers are suitable for visible-to-near infrared photodetection owing to their tunable optical bandgaps. Also, their superior mechanical deformability enabled by an extremely small thickness and van der Waals (vdW) assembly allows them to be structured into unconventional physical forms, unattainable with any other materials. Herein, we demonstrate a new type of 2D MoS2 layer-based rollable photodetector that can be mechanically reconfigured while maintaining excellent geometry-invariant photo-responsiveness. Large-area (>a few cm2) 2D MoS2 layers grown by chemical vapor deposition (CVD) were integrated on transparent and flexible substrates composed of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNs) by a direct solution casting method. These composite materials in three-dimensionally rollable forms exhibited a large set of intriguing photo-responsiveness, well preserving intrinsic opto-electrical characteristics of the integrated 2D MoS2 layers; i.e., light intensity-dependent photocurrents insensitive to illumination angles as well as highly tunable photocurrents varying with the rolling number of 2D MoS2 layers, which were impossible to achieve with conventional photodetectors. This study provides a new design principle for converting 2D materials to three-dimensional (3D) objects of tailored functionalities and structures, significantly broadening their potential and versatility in futuristic devices.

BACKGROUND Clinical differentiation between pigmented basal cell carcinoma (BCC) and seborrheic keratosis (SK) can sometimes be difficult. Noninvasive diagnostic technologies, such as thermal imaging, can be helpful in these situations. This study explored the use of dynamic thermal imaging (DTI), which records thermal images after the application of external thermal stimuli (heat or cold) for the differential diagnosis of pigmented BCC and SK. MATERIALS AND METHODS Twenty-two patients with pigmented BCC and 15 patients with SK participated in this study. Dynamic thermal images of lesions (pigmented BCC or SK) and control sites (contralateral normal skin) were recorded after the heat and cold stimuli. Temperature changes in the region of interest (ROI) are plotted as a thermal response graph. After fitting an exponential equation to each thermal response graph, the rate constants were compared between groups (pigmented BCC versus control, SK versus control). RESULTS The thermal response graphs revealed that the average temperature of pigmented BCC showed faster thermal recovery to baseline than the control site. There was a significant difference in the rate constants of the fitted exponential equations between the pigmented BCCs and the control sites (p

In early studies on organic solar cells with high conductivity PEDOT:PSS, the contact between ITO and PEDOT:PSS was considered ohmic. However, because low-conductivity PEDOT:PSS (such as AI4083) is mainly utilized in contemporary solar cells, the contact between ITO and PEDOT:PSS is not ohmic anymore. Despite the high possibility that there are serious interface problems, little attention has been paid to the interface between PEDOT:PSS and ITO. Most of the previous studies of interfaces in organic solar cells have focused on the interface between the active and charge transport layers. In this work, we have employed a conjugated polyelectrolyte that uses potassium poly[9,9-bis(3′-sulfonatopropyl)fluorene-alt-(9-(2,7-diethylheptyl)-carboazole)] (WPFSCz-) between ITO and low-conductivity PEDOT:PSS to overcome complicated organic–inorganic interfacial problems. The insertion of the WPFSCz- layer provides substantial advantages in the operation of polymer solar cells. First, the inserted WPFSCz- layer modifies the work-function of ITO, thereby forming an effective cascading energy alignment, which is favorable for good hole transport. Second, the introduction of the WPFSCz- layer eliminates interfacial trap sites. The reduction in traps reduces recombination losses at the interface, resulting in an improvement in the fill factor. These effects result in a significant increase in the efficiency of non-fullerene solar cells based on PM6 and Y6, from 15.86 to 17.34%. In addition, we have found that the problem of the interface in contact with ITO occurs not only in PEDOT:PSS, but also in oxide-based charge transport layers. We have confirmed that the insertion of the WPFSCz- layer between ITO and an MoO3 (or ZnO) charge transport layer shows the same positive results.

Sonication of gallium or gallium-based liquid metals in an aqueous solution of vinyl monomers leads to rapid free radical polymerization (FRP), without the need for conventional molecular initiators. Under ambient conditions, a passivating native oxide separates these metals from solution and renders the metal effectively inert. However, sonication generates liquid metal nanoparticles (LMNPs) of ∼100 nm diameter and thereby increases the surface area of the metal. The exposed metal initiates polymerization, which proceeds via a FRP mechanism and yields high molecular weight polymers that can form physical gels. Spin trapping EPR reveals the generation of free radicals. Time-of-flight secondary ion mass spectrometry measurements confirm direct polymer bonding to gallium, verifying the formation of surface-anchored polymer grafts. The grafted polymers can modify the interfacial properties, that is, the preference of the metal particles to disperse in aqueous versus organic phases. The polymer can also be degrafted and isolated from the particles using strong acid or base. The concept of physically disrupting passivated metal surfaces offers new routes for surface-initiated polymerization and has implications for surface modification, reduction reactions, and fabrication of mechanically responsive materials.

Surgeons usually used short screws to avoid extensor tendon problems during volar locking plate fixation in distal radius fracture. However, the stability according to the length of distal locking screws have not been fully understood. We investigated this issue through finite element analysis and compression test using synthetic radius. Our results demonstrated that the bi-cortical full-length fixation does not contribute to the stiffness increase in the axial compression direction, and a reduction in length of up to more than 50% length can still provide similar stability to full-length screws. Our data can support that surgeon should undersize the distal screw.

Quantitative understanding of nanoscale interactions is a prerequisite for harnessing the remarkable collective properties of nanoparticle systems. Here, we report the combined use of liquid-phase transmission electron microscopy and electron beam lithography to elucidate the interactions between charged nanorods in a predefined potential energy landscape. In situ site-selective lift-off of surface-functionalized lithographed gold nanorods is achieved by patterning them with adhesion layer materials that undergo etching at different rates. Analysis of the subsequent nanorod motion, which is two-dimensionally confined as a result of the particle-substrate attraction, allows quantification of interparticle interactions in a lithographically engineered environment. For lithographed nanorods patterned with the same adhesion layer material, their self-assembly behavior following lift-off is tuned by changing their starting spatial arrangement. Our approach facilitates investigation of interparticle interactions in designed nanoparticle systems and affords fundamental insights into the role of the potential energy landscape in determining the kinetic pathway for nanoparticle self-assembly.

Synthesis of cobalt boride nanoparticles and h-BN nanocage encapsulation were conducted using a triple direct current (DC) thermal plasma jet system. Mixed cobalt and boron powder were used as the starting material. The thermal plasma jet was generated using mixed Ar–N2 and Ar–H2 gases. The nanostructure of the synthesized nanoparticles varied according to the gas composition. In the Ar–N2 plasma, the dissociated nitrogen anticipated a chemical reaction with the boron precursor and synthesized h-BN nanocages that encapsulated cobalt boride nanoparticles, additionally, c-BN nanoparticles were synthesized. In the Ar–H2 plasma, only

Two-dimensional (2D) molybdenum disulfide (MoS2) with vertically aligned (VA) layers exhibits significantly enriched surface-exposed edge sites with an abundance of dangling bonds owing to its intrinsic crystallographic anisotropy. Such structural variation renders the material with exceptionally high chemical reactivity and chemisorption ability, making it particularly attractive for high-performance electrochemical sensing. This superior property can be further promoted as far as it is integrated on mechanically stretchable substrates well retaining its surface-exposed defective edges, projecting opportunities for a wide range of applications utilizing its structural uniqueness and mechanical flexibility. In this work, we explored VA-2D MoS2 layers configured in laterally stretchable forms for multifunctional nitrogen dioxide (NO2) gas sensors. Large-area (>cm2) VA-2D MoS2 layers grown by a chemical vapor deposition (CVD) method were directly integrated onto a variety of flexible substrates with serpentine patterns judiciously designed to accommodate a large degree of tensile strain. These uniquely structured VA-2D MoS2 layers were demonstrated to be highly sensitive to NO2 gas of controlled concentration preserving their intrinsic structural and chemical integrity, e.g., significant current response ratios of ∼160-380% upon the introduction of NO2 at a level of 5-30 ppm. Remarkably, they exhibited such a high sensitivity even under lateral stretching up to 40% strain, significantly outperforming previously reported 2D MoS2 layer-based NO2 gas sensors of any structural forms. Underlying principles for the experimentally observed superiority were theoretically unveiled by density functional theory (DFT) calculation and finite element method (FEM) analysis. The intrinsic high sensitivity and large stretchability of VA-2D MoS2 layers confirmed in this study are believed to be applicable in sensing diverse gas species, greatly broadening their versatility in stretchable and wearable technologies.

The electrochemical N2 reduction reaction has attracted interest as a potential alternative to the Haber–Bosch process, but a significantly low conversion efficiency and a significantly low ammonia...

We control the aggregation of short-side-chain (SSC) perfluorinated sulfonic acid (PFSA) ionomers for catalyst-layer (CL) inks by using a dispersion solvent of dipropylene glycol (DPG) and water. By increasing the fraction of PFSA backbone preferable DPG content in a dispersion solvent, the size of SSC-PFSA aggregates decreases exponentially from microscale to nanoscale, affecting the catalyst-ionomer agglomerates’ size and distribution in the CL inks. The surface morphology and porosity properties of the resulting CL are investigated, and the fuel cell performances are studied at two different humidity conditions (50 and 100% RH). Compared to the previous study with long-side-chain (LSC) PFSA ionomers, the SSC-PFSA ionomers show the optimized performance at higher DPG content, where the solvating power is intermediate for SSC-PFSA ionomers having shorter hydrophilic side chain than LSC-PFSA ionomers.

We explored the feasibility of wafer-scale two-dimensional (2D) molybdenum disulfide (MoS2) layers toward futuristic environmentally friendly electronics that adopt biodegradable substrates. Large-...

Platinum diselenide (PtSe2) is an emerging class of two-dimensional (2D) transition metal dichalcogenide (TMD) crystals recently gaining substantial interests owing to its extraordinary properties ...

Fibrous network of highly-integrated CNTs/MoO3 composite bundle in which CNTs anchored with MoO3 nanoplates was prepared by electrospinning process and subsequent simple heat-treatment. By performing the pre-acid-treatments of both CNTs and PAN, dipole-dipole interactions and hydrogen bonding between CNTs and PAN could form MoO2(acac)2-PAN-CNTs complex in a solution, which allows for the formation of a stable jet during electrospinning. Notably, by selectively removing PAN in as-spun fibers during heat-treatment, a highly integrated CNTs/MoO3 bundle network anchored with MoO3 nanoplates was obtained. This unique CNTs/MoO3 percolation network makes it possible to achieve a superior lithium ion storage performance by improving electrical conductivity and structure stability. Thus, the unique nanostructure has high discharge capacities of 972 mA h g−1 after 100 cycles at 1.0 A g−1 and 905 mA h g−1 after 800 long-term cycles at 2.0 A g−1, when applied as anode materials for lithium-ion batteries. The discharge capacities of 980, 920, 819, 742, 599, 484, and 374 mA h g−1 were observed at current densities of 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 10.0 A g−1, respectively.

Platinum ditelluride (PtTe2) is an emerging semimetallic two-dimensional (2D) transition-metal dichalcogenide (TMDC) crystal with intriguing band structures and unusual topological properties. Despite much devoted efforts, scalable and controllable synthesis of large-area 2D PtTe2 with well-defined layer orientation has not been established, leaving its projected structure-property relationship largely unclarified. Herein, we report a scalable low-temperature growth of 2D PtTe2 layers on an area greater than a few square centimeters by reacting Pt thin films of controlled thickness with vaporized tellurium at 400 °C. We systematically investigated their thickness-dependent 2D layer orientation as well as its correlated electrical conductivity and surface property. We unveil that 2D PtTe2 layers undergo three distinct growth mode transitions, i.e., horizontally aligned holey layers, continuous layer-by-layer lateral growth, and horizontal-to-vertical layer transition. This growth transition is a consequence of competing thermodynamic and kinetic factors dictated by accumulating internal strain, analogous to the transition of Frank-van der Merwe (FM) to Stranski-Krastanov (SK) growth in epitaxial thin-film models. The exclusive role of the strain on dictating 2D layer orientation has been quantitatively verified by the transmission electron microscopy (TEM) strain mapping analysis. These centimeter-scale 2D PtTe2 layers exhibit layer orientation tunable metallic transports yielding the highest value of ∼1.7 × 106 S/m at a certain critical thickness, supported by a combined verification of density functional theory (DFT) and electrical measurements. Moreover, they show intrinsically high hydrophobicity manifested by the water contact angle (WCA) value up to ∼117°, which is the highest among all reported 2D TMDCs of comparable dimensions and geometries. Accordingly, this study confirms the high material quality of these emerging large-area 2D PtTe2 layers, projecting vast opportunities employing their tunable layer morphology and semimetallic properties from investigations of novel quantum phenomena to applications in electrocatalysis.

Modern electronics have been geared toward exploring novel electronic materials that can encompass a broad set of unusual functionalities absent in conventional platforms. In this regard, two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors are highly promising, owing to their large mechanical resilience coupled with superior transport properties and van der Waals (vdW) attraction-enabled relaxed assembly. Moreover, 2D TMD heterolayers based on chemically distinct constituent layers exhibit even more intriguing properties beyond their mono-component counterparts, which can materialize only when they are manufactured on a technologically practical wafer-scale. This mini-review provides a comprehensive overview of recent progress in exploring wafer-scale 2D TMD heterolayers of various kinds. It extensively surveys a variety of manufacturing strategies and discusses their scientific working principles, resulting 2D TMD heterolayers, their material properties, and device applications. Moreover, it offers extended discussion on remaining challenges and future outlooks toward further improving the material quality of 2D TMD heterolayers in both material and manufacturing aspects.

Comonomers vinylimidazole, methyl acrylate, and acrylic acid were added to acrylonitrile to synthesize two polymers, poly(acrylonitrile-co-1-vinylimidazole) and poly(acrylonitrile-co-N-vinylimidazole-co-methyl acrylate-co-acrylic acid), with the goal of enhancing their melt processability for their use as carbon fibers. The two polymers were melt-extruded, but the as-spun filaments were brittle. Therefore, glycerol was mixed with the polymers to improve their spinnability and drawability. The addition of glycerol to the polyacrylonitrile copolymer and tetrapolymer reduced their melt viscosity, enhanced their melt spinnability, and improved their drawability. When 15 % (w/w) glycerol was added, the melt viscosity of the two polymers was reduced to below 1000 Pa·s at a shear rate of 100 s-1, and the tensile strength of the resulting filaments was high enough for them to be used as precursor filaments for carbon fibers. Furthermore, a draw ratio of over 5.5 was achieved for the melt spun filaments of mixtures of the copolymer and tetrapolymer with 15 % glycerol (w/w) at a temperature of 150 °C.

An appropriate water balance between the conservation of the membrane humidity and the reduction of excess water in the cell remains a key challenge for commercialization of polymer electrolyte fuel cells (PEFCs). Here, we report a microporous layer (MPL) consisting of line patterns with different morphologies by using inkjet printing method, which provides a better water transport pathway not limiting by mass transport for reactant gases to reach the catalyst layer. The pattern-MPL coated on the gas diffusion backing layer (P-GDL) increases the power performance at 50 and 32% RH conditions comparing to commercial one (SGL, 39BC). This result suggests that the in-plane different porous pattern of MPL possesses the significant potential to improve the PEFCs performance with the water balance in the membrane/electrode assembly (MEA).

Oil spills are a major threat to the marine ecosystem, requiring immediate solutions to remove spilled oil from oceanic environments. In this study, we report a superhydrophobic molybdenum disulfide (MoS2) coated polydimethylsiloxane (PDMS) sponge and demonstrate its high proficiency in spilled oil recovery and oil spill detection based on oil-water separation ability. This novel oil sorbent is fabricated by a simple dip-coating to incorporate MoS2 flakes into PDMS sponge. The optimized MoS2-sponge displays a water contact angle of >152°, demonstrating excellent superhydrophobicity and high oil absorption (>97 wt%) for a variety of oils, including vegetable oil and fuel waste. Moreover, the material retains excellent oil absorption capability upon repetitive compression cycles. The versatility of this novel sorbent has been extended for the real-time spontaneous detection of oils by taking advantage of electrically conductive MoS2 layers.

The impact of topological defects associated with grain boundaries (GB defects) on the electrical, optical, magnetic, mechanical and chemical properties of nanocrystalline materials1,2 is well known. However, elucidating this influence experimentally is difficult because grains typically exhibit a large range of sizes, shapes and random relative orientations3-5. Here we demonstrate that precise control of the heteroepitaxy of colloidal polyhedral nanocrystals enables ordered grain growth and can thereby produce material samples with uniform GB defects. We illustrate our approach with a multigrain nanocrystal comprising a Co3O4 nanocube core that carries a Mn3O4 shell on each facet. The individual shells are symmetry-related interconnected grains6, and the large geometric misfit between adjacent tetragonal Mn3O4 grains results in tilt boundaries at the sharp edges of the Co3O4 nanocube core that join via disclinations. We identify four design principles that govern the production of these highly ordered multigrain nanostructures. First, the shape of the substrate nanocrystal must guide the crystallographic orientation of the overgrowth phase7. Second, the size of the substrate must be smaller than the characteristic distance between the dislocations. Third, the incompatible symmetry between the overgrowth phase and the substrate increases the geometric misfit strain between the grains. Fourth, for GB formation under near-equilibrium conditions, the surface energy of the shell needs to be balanced by the increasing elastic energy through ligand passivation8-10. With these principles, we can produce a range of multigrain nanocrystals containing distinct GB defects.

We synthesize ZnS–ZnO heterostructure nanorings at ∼680 °C under carrier gases with various [CO2]/[N2] ratios simulating an anoxic and weakly reduced atmosphere on early Earth. The synthesized nanorings consist of a ZnS–ZnO bilayered stem, ZnO teeth, and ZnS wing-like structures between the teeth and the ZnS layer. O atoms are supplied through the decomposition of CO2 presumably catalyzed by the ZnS surface. The respective growth directions of ZnS and ZnO layers in the stem are [0001] and [0111], and ZnO teeth are directed outward from the ring. The nanorings are structurally different from ZnS–ZnO nanorings having inward-directed teeth, which were grown under an oxygen-containing ambient environment. Contrary to the assumption of sulfide dominance including ZnS and MnS while disregarding oxygen-containing minerals such as ZnO on early Earth, we show that ZnS–ZnO nanorings, which are more advantageous in CO2 reduction efficiency, could be formed.

Two-dimensional (2D) transition metal dichalcogenide (TMD) layers have gained increasing attention for a variety of emerging electrical, thermal, and optical applications. Recently developed metallic 2D TMD layers have been projected to exhibit unique attributes unattainable in their semiconducting counterparts; e.g., much higher electrical and thermal conductivities coupled with mechanical flexibility. In this work, we explored 2D platinum ditelluride (2D PtTe2) layers - a relatively new class of metallic 2D TMDs - by studying their previously unexplored electro-thermal properties for unconventional window applications. We prepared wafer-scale 2D PtTe2 layer-coated optically transparent and mechanically flexible willow glasses via a thermally-assisted tellurization of Pt films at a low temperature of 400 °C. The 2D PtTe2 layer-coated windows exhibited a thickness-dependent optical transparency and electrical conductivity of >106 S m-1 - higher than most of the previously explored 2D TMDs. Upon the application of electrical bias, these windows displayed a significant increase in temperature driven by Joule heating as confirmed by the infrared (IR) imaging characterization. Such superior electro-thermal conversion efficiencies inherent to 2D PtTe2 layers were utilized to demonstrate various applications, including thermochromic displays and electrically-driven defogging windows accompanying mechanical flexibility. Comparisons of these performances confirm the superiority of the wafer-scale 2D PtTe2 layers over other nanomaterials explored for such applications.

We present a novel structure for topologically protected propagation of mechanical waves in a continuous, elastic membrane using an analog of the quantum valley Hall effect. Our system involves a thin, continuous graphene monolayer lying on a pre-patterned substrate, and as such, it can be employed across multiple length scales ranging from the nano to macroscales. This enables it to support topologically-protected waves at frequencies that can be tuned from the kHz to GHz range by either selective pre-tensioning of the overlaying membrane, or by increasing the lattice parameter of the underlying substrate. We show through numerical simulations that this continuous system is robust against imperfections, is immune to backscattering losses, and supports topologically-protected wave propagation along all available paths and angles. We demonstrate the ability to support topologically-protected interface modes using monolayer graphene, which does not intrinsically support topologically non-trivial elastic waves.

Resistance spot welding, which is the dominant welding process with high productivity for manufacturing car body and other components, is widely used to weld various steel sheets in automotive industry. However, electrode indentation affects both the surface quality and mechanical property of resistance spot welded lap joint. Variation in the tip diameter of upper electrode and use of copper plate at the lower electrode side are an effective recourse to get sound surface appearance with reduced indentation depth due to lower current intensity. In present study, with 10 mm thick copper plate on lower electrode side, resistance spot welding of 1.2 and 1.6 mm thick cold rolled steel sheets has been performed to examine the effect of upper electrode tip diameter on formation of indentation depth and nugget diameter. The result exhibits that larger electrode tip diameter significantly reduced indentation depth on optimal nugget size corresponding to Korean Industrial Standard requirements for resistance spot welding. In case of welding in 1.2 mm thick steel sheets using electrode tip diameter of 8 mm, nugget diameter increased with increasing welding current and then the maximum tensile shear load was 6.55 kN under welding current of 10 kA. The maximum tensile shear load of 1.6 mm thick steel sheets reached 11.28 kN under welding current of 11 kA.

The physics of vacuum arc spot operation remains subject of research due to difficulties associated with short characteristic times (ns to μs) and short length scales (μm or even smaller). The advancement of modern plasma diagnostic technologies may allow us to probe arc spot plasma with higher spatial and temporal resolution than before. In this contribution, we report on the evolution of arc spots using a steered arc plasma source which is in its construction similar to a linear sputtering magnetron: the E x B field is utilized to have some control of spot locations while performing the study. The main plasma diagnostics tool we employ is a streak camera with an image intensifier which allows us to observe the dynamics of the optical emission of arc spots in various sweep time intervals (50 μs, 10 μs, 1 μs, and 500 ns). The observed spot shows self-similar patterns in the emitted light with different sweep times.

When a crack occurs under an installed waterproofing material and moves due to environmental effects (freeze–thaw, settlement, vibration, dead load, etc.), waterproofing materials without adequate elongation or tensile strength properties may break and tear. To enable the selection of materials with proper response against the strain that occur during crack movement, this study proposes and demonstrates a new evaluation method for determining and comparing strain concentration of waterproofing materials under the effect of concrete crack movement. For the proposed testing method and demonstration, three common types of waterproofing material types were selected for testing, poly-urethane coating (PUC), self-adhesive asphalt sheet (SAS) and composite asphalt sheet (CAS). Respective materials are installed with strain gauges and applied onto a specimen with a separated joint that undergoes concrete crack movement simulation. Each specimen types are subject to repeated movement cycles, whereby strain occurring directly above the moving joint is measured and compared with the strain occurring at the localized sections (comparison ratio which is hereafter referred to as strain concentration ratio). Specimens are tested under four separate movement length conditions, 1.5 mm, 3.0 mm, 4.5 mm and 6.0 mm, and the results are compared accordingly. Experimental results show that materials with strain concentration ratio from highest to lowest are as follows: PUC, SAS and CAS.

Titanium, nickel, and tungsten boride nanoparticles were synthesized in the triple thermal plasma jet system. The coalesced high-enthalpy thermal plasma jet not only generates extensive high temperature regions but also allows the starting materials to penetrate into the center of high temperature regions effectively. The synthesis process of metal boride was investigated according to the nucleation temperature of three metals and boron. In the case of titanium and nickel borides synthesis, metals nucleation temperatures are lower than boron. The crystallinity of synthesized titanium boride nanoparticles was higher than nickel boride nanoparticles, since not only the nucleation temperature of titanium is higher than nickel but also the Gibbs free energy of all titanium boride was lower than whole nickel boride. However, the nucleation temperature of tungsten is higher than boron where nanoparticle synthesis process differed from former synthesis processes. It had influence on the crystal growth time in the high temperature regions where tungsten boride crystal structure was strongly prepared than nickel boride nanoparticles.

Nanostructured cellulose fabric with an air-bubble-enhanced anti-oil fouling property is introduced for quick oil-cleaning by water even with the surface fouled by oil before water contact under a dry state. It is very challenging to recover the super-hydrophilicity because once the surface is oil-fouled, it is hard to be re-wetted by water. Anti-oil-fouling under a dry state was realized through two main features of the nanostructured, porous fabric: a low solid fraction with high-aspect-ratio nanostructures significantly increasing the retracting forces, and trapped multiscale air bubbles increasing the buoyancy and backpressure for an oil-layer rupture. The nanostructures were formed on cellulose-based rayon microfibers through selective etching with oxygen plasma, forming a nanoscale open-pore structure. Viscous crude oil fouled on a fabric under a dry state was cleaned by immersion into water owing to a higher water affinity of the rayon material and low solid fraction of the high-aspect-ratio nanostructures. Air bubbles trapped in dry porous fibers and nanostructures promote oil detachment from the fouled sites. The macroscale bubbles add buoyancy on top of the oil droplets, enhancing the oil receding at the oil-water-solid interface, whereas the relatively smaller microscale bubbles induce a backpressure underneath the oil droplets. The oil-proofing fabric was used for protecting underwater conductive sensors, allowing a robot fish to swim freely in oily water.

In polymer electrolyte membrane fuel cell, the poor power performance of hydrocarbon (HC)-based membranes in low relative humidity conditions arises from the materials’ inherently inadequate proton conductivity under water-deficient conditions. In this study, we introduce boehmite into the catalyst layer as a water retention material to enhance the power performance of a HC-based membrane/electrode assembly (MEA) in low RH conditions. The addition of well-dispersed boehmite into the CCL increased the water concentration and consequently accelerated water back diffusion to the MEA at a low RH. The power performance also improved upon the addition of an optimal percent content of boehmite.

The tungsten carbide nanomaterials were synthesized in the triple DC thermal plasma jet system using refractory tungsten, and carbon sources such as multi wall carbon nanotube (MWCNT), amorphous carbon and methane. The starting materials were evaporated in the high temperature region of triple plasma jet, then condensed particles were prepared in nanoscale under 100 nm. The effect of carbon sources was investigated on a view of crystal phase structure and morphology. W₂C crystal nanoparticles were mainly synthesized and WC and WC1-x phase nanoparticles were observed additionally with all carbon sources. From MWCNT starting material, tungsten carbide attached MWCNT composite were produced with spherical tungsten carbide nanoparticles. In case of amorphous carbon, spherical and rod-shaped tungsten carbide was synthesized. Only spherical tungsten carbide nanoparticles were synthesized by methane. In addition, it was revealed that the main crystal structure was changed from W₂C to WC1-x by increasing W/CH₄ composition ratio.

Hierarchical yolk-shell-structured NiCoSe2/CNT [HYS-(NiCo)Se2/CNT] hybrid microspheres consisting of a porous yolk and embossed hollow thin shell were prepared by one-step spray pyrolysis and subsequent selenization heat treatment for potential use as anode materials for sodium-ion batteries. The unique HYS-(NiCo)Se2/CNT microspheres had a hierarchical configuration of an external thin shell, inside porous yolk, and interstitial hollow space. In particular, the porous yolk is composed of CNTs walls and contained interconnected mesopores formed by PS decomposition during one-step spray pyrolysis. The discharge capacity of the HYS-(NiCo)Se2/CNT microspheres was 366 mA h g−1 after 10,000 cycles at a high current density of 3.0 A g−1, and their capacity retention after the 2nd cycle was 85%. The HYS-(NiCo)Se2/CNT microspheres have discharge capacities of 444, 429, 400, 380, 352, 329, 300, 266, 222, and 163 mA h g−1 at current densities of 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, 10.0, 12.0, 15.0 and 20.0 A g−1, respectively. The synergistic effects of the uniquely hierarchical yolk-shell structure, CNTs walls with high electrical conductivity, interstitial mesopores, and anchored (Ni,Co)Se2 nanoparticles resulted in high structural stability during the cycles and excellent sodium-ion storage performance.

The phase velocity of the wakefield of a laser wakefield accelerator can, theoretically, be manipulated by shaping the longitudinal plasma density profile, thus controlling the parameters of the generated electron beam. We present an experimental method where using a series of shaped longitudinal plasma density profiles we increased the mean electron peak energy more than 50%, from 175 ± 1 MeV to 262 ± 10 MeV and the maximum peak energy from 182 MeV to 363 MeV. The divergence follows closely the change of mean energy and decreases from 58.9 ± 0.45 mrad to 12.6 ± 1.2 mrad along the horizontal axis and from 35 ± 0.3 mrad to 8.3 ± 0.69 mrad along the vertical axis. Particle-in-cell simulations show that a ramp in a plasma density profile can affect the evolution of the wakefield, thus qualitatively confirming the experimental results. The presented method can increase the electron energy for a fixed laser power and at the same time offer an energy tunable source of electrons.

Two zinc oxide (ZnO) morphologies, nanorods and nanoplates, were synthesized using solvothermal synthesis, and the effect of the ZnO morphologies on the UV absorbance and anitmicrobial activity of nylon 6/ZnO composite filaments was investigated. The ZnO nanorods and nanoplates exhibited a hexagonal wurtzite crystal structure. The ZnO nanorods were 50 nm in diameter and 300 nm in length, and the ZnO nanoplates were 150 nm in width and 25 nm in thickness. Photoluminescence (PL) measurements showed that the intensity of the deep level emission of the ZnO plates in the visible light range was lower than that of the ZnO nanorods, indicating that amount of surface defects on the ZnO nanoplates was relatively small compared that of the ZnO nanorods. The strong crystal diffraction peaks of the ZnO nanorods confirmed that they exhibited higher crystallinity than the ZnO nanoplates. Both the nylon 6/ZnO nanorod and nylon 6/ZnO nanoplate composite filaments showed very good antimicrobial activity even when only 0.5 wt% of ZnO particles was added. The specific surface area of the ZnO nanorods and nanoplates were 10.353 and 11.249 m2/g, respectively. UV protection of the nanoplates was higher than that of the nanorods. The larger specific surface area of the ZnO nanoplates led to higher UV absorbance of the nylon 6/ZnO nanoplate composite filaments.

Triple dc plasma torch system was used for the synthesis of nanoparticles. Three thermal plasma jets are ejected from each plasma torch and they are merged into a strong single plasma plume. Since the feedstock is injected into the jet merging area, this system is suitable for refractory nanoparticle synthesis and enable to high production yield caused by the complete evaporation is possible. In this paper, numerical simulation was carried out to analyze thermal plasma characteristic inside a reactor according to the plasma-forming gas and carrier gas compositions: Ar, Ar–H2, and Ar–N2 plasma; Ar, He, and N2 carrier gas. Then, it was comparatively interpreted with the actually synthesized nanoparticle in order to understand the condensation process of nanoparticles. It was revealed that the thermal environment is able to control readily in the triple torch system by the operating condition depending on the target materials.