Search

Induced joint is seen as a kind of crack prevention measure for roller compacted concrete arch dam. Whether induced joints can crack firstly when the temperature drops of dam body to release temperature stress and control disordered cracks mainly depends on the equivalent strength, structural form and arrangement of joints. In this paper, the non-penetrating RCC induced joints are used to simulate the bilateralism interval induced joints in practical engineering. The functional relation between the equivalent strength of rectangular induced joints and elliptical induced joints with the change of weakening degree is established through the axial tension test. At the same time, the temperature stress of a certain RCC double curvature arch dam is simulated, and the cracking of induced joints and its effect on the stress of the dam are analyzed. The results show that under the temperature control measures of pouring temperature control and water cooling in the whole dam, the bilateralism interval induced joints with equivalent strength less than 1.409 MPa are set in the high tension stress zone of the dam body, which can effectively release the temperature stress and ensure the safety of the dam body under the temperature load.

Materials that can efficiently absorb electromagnetic waves (EMWs) are required to deal with electromagnetic pollution. Structure design appears to be an efficient way to improve the EMW-absorption performance of such materials, particularly when adjustment of the constitution or mixing ratio is limited. In this study, bowl-like and honeycomb titanium dioxide/carbon nanotube (TiO2/CNT) composites with different CNT contents were fabricated using the methods of hierarchical and mixing vacuum-assisted filtration, respectively. Compared to the honeycomb structure, the bowl-like structure simultaneously facilitated greater interfacial polarization and conduction loss in favor of dielectric polarization, and augmented multiple reflections. The high porosity of the honeycomb structure was conducive to optimizing the impedance matching characteristics. The bowl-like TiO2/CNT composite exhibited a minimum reflection loss (RLmin) of −38.6 dB (1.5 mm) with a wide effective absorption band (EAB

To tackle the dissolution problem of boron carbide particles in silicon infiltration process, carbon-coated boron carbide particles were fabricated for the preparation of the reaction-bonded boron carbide composites. The carbon coating can effectively protect the boron carbide from reacting with liquid Si and their dissolution, thus maintaining the irregular shape of boron carbide particles and preventing the growth of boron carbide particles and reaction formed SiC regions. Furthermore, the nano-SiC particles, originated from the reaction of the carbon coating and the infiltrated Si, uniformly coated on the surfaces of boron carbide particles, thus forming a ceramic skeleton of the nano-SiC particles-coated and -bonded boron carbide particles. The Vickers hardness, flexural strength and fracture toughness of the composites can be increased by 26 %, 45 %, and 37 % respectively, by using carbon-coated boron carbide particles as raw materials.

The nanotube-consisted flower-like NiCo2S4 is successfully fabricated by a novel two-step hydrothermal technique. X-ray diffraction (XRD) identifies the spinel structure, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imply the flower-like morphology of the synthesized NiCo2S4. The electrochemical behaviors are studied by cyclic voltammetry and galvanostatic charge-discharge measurements. The NiCo2S4 nanotubes demonstrate enhanced pseudocapacitive performance of 429.5 C g-1 at current density of 0.5 A g-1. The NiCo2S4//AC device delivers high energy density of 37.69 Wh kg-1, maximum power density of 4000.6 W kg-1 and satisfied cycle property of 96% capacitance retention after over 7000 cycles. The results show that the NiCo2S4 nanotubes are promising electrode material for high performance supercapacitor applications.

CrAlN coatings were synthesized on pre-plasma nitrided M2 high speed steels using different ion current densities. The effect of plasma nitriding pretreatment on the microstructures and tribological properties of composite CrAlN coatings had been studied. The results showed that the nitriding efficiency could be significantly enhanced by higher ion current density. The thickness of nitrided layer increased from 43 μm to 63 μm with the increase of ion current density. The nitrided layers without either compound layer or grain boundary precipitation were produced with all experimental ion current densities. Radial cracks also appeared at the Rockwell-C indentation edge of the composite CrAlN coating due to the conformal effect. Moreover, radial cracks of the composite coatings originated from the hard and brittle nitrided layer. The highest interfacial adhesion of the composite CrAlN coating reached 105 N. Furthermore, the wear resistance of CrAlN coating was improved by combining nitriding pretreatment with coating deposition, and the composite coating (PN4/CrAlN) possessed the superior wear resistant.

Cr(VI)-based compounds pollution have attracted global concern due to serious harm to humans and environment. Hence, it is crucial to exploit an effective technique to eliminate Cr(VI) in water. Herein, we in-situ grown BiOI on graphitic carbon nitride to prepare the BiOI/g-C3N4 (BCN) direct Z-scheme heterojunction by solid phase engineering method at room temperature. Experimental result shown the photocatalytic activity of pure BiOI were obviously enhanced by constructing Z-scheme BCN heterostructure, and BCN-3 heterostructure exhibited the optimal photocatalytic degradation of RhB with 98% yield for 2.5 h and reduction of Cr(VI) with more than 99% yield for 1.5 h at pH = 2. Stability test shows BCN-3 still kept more than 98% reduction efficiency after 6 cycles. In addition, we also studied the reduction mechanism that shown the ·O2− radicals essentially helped to reduce the Cr(VI) in aqueous solution under illumination, verified the direct Z-scheme charge transfer path by X-ray photoelectron spectroscopy (XPS) and the free radical trapping experiment. The work open a new way for rationally designing photocatalyst heterostructure to reduce Cr(VI) to Cr(III).

The spatial–temporal evolution of coherent structures generated by an asymmetrical dielectric barrier discharge (DBD) plasma actuator is an intriguing unsteady process with profound implications fo...

In this paper, ordered mesoporous alumina (OMA) support with the high surface area (328 m2·g-1) and the large pore volume 0.74 (cm3·g-1) was synthesized by homogeneous precipitation method. And the influence of EDTA on the physical and chemical properties of the modified catalysts was also studied. The characteristic results showed that the addition of EDTA could adjust the metal-support interaction and improved the acidity of the corresponding catalyst. Combined with the catalytic performance results, the EDTA-modified NiMoE(1.0)/OMA catalyst displays the highest DBT hydrodesulfurization conversion (97.7%).

InGaO3(ZnO)m (m = 1, 2, 3, 4, and 5) ceramics are a series of n-type oxide thermoelectric materials with layered structures and low thermal conductivities. Herein, InGaO3(ZnO)m (m = 1, 2, 3, 4, and 5) ceramics were fabricated by spark plasma sintering (SPS). Two different trends in the thermoelectric properties of the InGaO3(ZnO)m (m = 1, 2, 3, 4, and 5) ceramics were observed depending on the odevity of the m value. The InGaO3(ZnO) sample exhibited a relatively high electrical conductivity and was therefore selected for vacuum annealing to further improve the electrical transport performance. Oxygen vacancy defects were introduced to the matrix during the annealing procedure, which improved the thermoelectric performance. A maximum ZT of 0.45 was obtained at 973 K for the InGaO3(ZnO) sample with a 96 h vacuum annealing treatment, which is 30 times higher than that of the pristine sample.

New amphiphilic carbazole-based dyes assemble in water into deep-blue-emitting, highly fluorescent helical aggregates as observed by transmission electron microscopy and atomic force microscopy. Single crystal X-ray diffraction and NMR spectroscopy reveal that self-complementary, antiparallel H-bonding and π-π stacking interactions are the driving forces for the formation of these dye aggregates.

Among the solid electrolytes studied for all-solid-state sodium batteries (ASSBs), Na3SbS4 (NAS) appears particularly promising due to its unique combination of high ionic conductivity and compatib...

Polymer dielectrics have drawn great attentions for applications in advanced electronic devices and power grids because of their high breakdown strength, low dielectric loss, and excellent flexibility. However, the low energy density in polymer dielectric capacitors will hinder the continuous miniaturization of electrical systems. In this work, ultraviolet irradiation is demonstrated to greatly enhance the breakdown strength and energy density of polypropylene. Dramatically improved breakdown strength of 867 MV/m and discharged energy density of 8.0 J/cm3, together with the high energy efficiency of >90%, were simultaneously achieved in polypropylene after ultraviolet irradiation. Our research shows that proper ultraviolet irradiation can effectively improve the energy density of polypropylene without sacrificing its high charge‐discharge efficiency, being potential for applications in power electronics and pulse electric systems.

In this study, a fully biodegradable ultra-light poly(lactic acid)/silicon dioxide (PLA/SiO2) aerogel nanocomposite with ultra-low thermal conductivity was successfully fabricated. PLA used was a produced from lactic acid, where the lactic acid has been produced from carbohydrates. The rheological properties of PLA were enhanced by diphenylmethane diisocyanate (MDI). The foaming properties, cell density, cell size uniformity, mechanical properties and thermal conductivity and thermal diffusivity of PLA were further improved by SiO2 aerogel, and finally the ultra-low density foamed material was prepared by supercritical CO2. The density of PLA foam can be as low as 0.02 g/cm3 and the thermal conductivity as low as 0.02628 W/m·K. The PLA-based composites can be used in many fields such as thermal insulation, vibration damping and packaging, and can be fully biodegradable and sustainable throughout their life cycle, which meets the global trend of energy saving and emission reduction.

Progress in understanding crystallization pathways depends on the ability to unravel relationships between intermediates and final crystalline products at the nanoscale, which is a particular challenge at elevated pressure and temperature. Here we exploit a high-pressure atomic force microscope to directly visualize brucite carbonation in water-bearing supercritical carbon dioxide (scCO2) at 90 bar and 50 °C. On introduction of water-saturated scCO2, in situ visualization revealed initial dissolution followed by nanoparticle nucleation consistent with amorphous magnesium carbonate (AMC) on the surface. This is followed by growth of nesquehonite (MgCO3·3H2O) crystallites. In situ imaging provided direct evidence that the AMC intermediate acts as a seed for crystallization of nesquehonite. In situ infrared and thermogravimetric–mass spectrometry indicate that the stoichiometry of AMC is MgCO3·xH2O (x = 0.5–1.0), while its structure is indicated to be hydromagnesite-like according to density functional theory and X-ray pair distribution function analysis. Our findings thus provide insight for understanding the stability, lifetime and role of amorphous intermediates in natural and synthetic systems. Non-classical crystallization may proceed through formation of intermediate phases, but it is not known whether these are linked to the final crystallization. Here, using an atomic force microscope at 90 bar, brucite carbonation is directly observed, with an amorphous intermediate acting as the seed for crystalline nesquehonite.

Ubiquitous crystals play an important role in our daily lives. Recent studies on the properties and formation of crystals have proven the attachment of particles ranging from ion pairs to well-crys...

In this paper, we report the fabrication of cobalt-doped de-NOx catalyst by pyrolyzing an analogous metal-organic framework-74 (MOF-74) containing Fe & Mn. The resulted catalyst exhibits distinctive microstructures of manganese, cobalt, and iron immobilized on N-doped carbon nanotubes (CNTs). It is found through experiments that the trimetallic catalyst Fe2Mn1Co0.5/CNTs-50 has the best NH3-selective catalytic reduction (SCR) performance. The Fe2Mn1Co0.5/CNTs-50 exhibited excellent water and sulfur resistance and good stability under the harsh gas environment of 250 °C and/or 170 °C, NO = NH3 = 1,000 ppm, 8 vol.% O2, 20 vol.% H2O, 1,000 ppm SO2, and gas hourly space velocity (GHSV) = 75,000 h−1. The de-NOx conversion was maintained about 55% and 25% after 192 h. The water and sulfur resistance performance were much higher than commercial vanadium series catalyst. The highly water and sulfur resistance performance may be attributed to the unique core-shell microstructure and the synergistic effect of manganese, cobalt, and iron which helps reduce the formation for byproducts (NH4HSO4). This study may promote to explore the development of a high stability catalyst for low-temperature selective catalytic reduction of NOx with NH3.

Due to its high strength, excellent electrical conductivity and high resistance to stress corrosion, Cu-Ni-Sn alloy has been selected as a kind of advanced metal material which can be used as the manufacture of springs, connectors, bearings and so on. In addition, the addition of Nb can efficiently improve the comprehensive properties of the alloy. In the present work, the effect of heat treatment conditions on microstructure and mechanical properties were studied in a Cu-9Ni-6Sn-0.22Nb alloy by means of optical microscopy (OM), transmission electron microscopy (TEM), tensile test and microhardness tests. The results show that before ageing, a large number of fine γ precipitates with DO22 type structure are distributed on the matrix. With the prolongation of ageing time, the ultimate tensile strength (UTS), yield strength (YS) and Vickers hardness increased firstly, and then decline. The reason can be attributed to the occurrence of spinodal decomposition and the formation of discontinuous precipitation (DP). At first, spinodal decomposition induced the enhanced interaction between dislocations and internal stress field, resulting in an increase of mechanical properties. Then the increased DP at grain boundaries leads to the decline of strength in the material. Finally, the relationship between the microstructure and the electrical conductivity was also analyzed, and the results show that the electrical conductivity increased with ageing time/ageing temperature increasing for the present alloy. Through the analysis of Matthiessen’ s rule, the variation of electrical resistivity depends on precipitates, solute atoms, dislocations, vacancies and grain boundaries, and the precipitates play an important role among them. Besides, more precipitates improve electrical conductivity. Therefore, the increase of ageing time/ageing temperature induced the increase of DP, resulting in an increase of electrical conductivity.

The search for high-energy-density materials (HEDMs) using polymeric nitrogen has attracted widespread attention in recent years. However, it is very difficult to synthesize polymeric nitrogen due ...

BSPIF-S-7.5A, a kind of open cell and low-density polyimide foam was developed for Chinese satellite. The polyimide foam is thermal isolation material with low thermal conductivity and high glass transition temperature. Basic physical properties, thermal physical properties, mechanical properties have been studied. For validating space environment resistance of polyimide foam, outgassing in vacuum, thermal cycle, total dose radiation, thermal vacuum and atomic oxygen tests have been performed. The apparent core density of this foam is as low as 7.5 ± 0.5 kg m−3. Its volume percentage of open cells is over 98%, which is beneficial to outgas in orbit. Coefficient of thermal expansion is less than 40 × 10–6 K−1 in the temperature range from − 170 to 135 ℃. Thermal conductivity in vacuum increases from 2.7 to 42.3 mW (m K)−1 with temperature rising from – 130 to 135 ℃. After severe space environment tests, thermal conductivity becomes even lower, compressive strength raises slightly, but shear property declines apparently. Covered with polyimide film, polyimide foam can resist atomic oxygen erosion effectively. Therefore, the polyimide foam is superior thermal insulation material for space application, which is ideal for satellite structure.

Pt3Ni alloy structure is an effective strategy to accelerate ethanol oxidation reaction (EOR), while the stability in acid electrolyte is the fatal weakness and the current density still needs to be enhanced. Herein, ultralong Pt3Ni nanowires tailored by trace Mo (Mo/Pt3Ni NWs) were successfully synthesized by surfactant free method. The specific activity of the optimized catalyst was 2.66 mA·cm−2, which is approximately 2.16 and 4.6-fold that of Pt3Ni NWs and commercial Pt/C catalyst, respectively. Most importantly, the Mo/Pt3Ni NWs catalyst showed negligible structure degradation after 3,000 cycles (42 h) of durability test in 0.1 M HClO4 and 0.5 M ethanol, as compared to severe structural collapse and Ni dissolution for the pure Pt3Ni NWs. The density functional theory (DFT) calculation also confirmed that both the surface and subsurface Mo atom could form Pt-Mo and Ni-Mo bonds with Pt and Ni, which were stronger than Pt-Ni bonds, to pin the Ni atoms in the unstable position and suppress the dissolution of surface Ni. The findings of this study indicate a promising pathway for the design and engineering of durable alloy nanocatalysts for direct ethanol fuel cell applications.

The key problems restricting the wide development of Ti3AlC2 material are the low hardness and strength. In this paper, MAX phase Ti3(Al,Si)C2 solid solutions with different Si doping were successfully synthesized using an in-situ reaction of Ti–Al–C system by powder metallurgy route. The phase structures and microstructures of the as-synthesized Ti3(Al,Si)C2 solid solutions were analyzed, the mechanical properties were tested, and the fracture surface morphologies were characterized. The results show that doping Si can prevent the lath-like structure of MAX phase from coarsening. When doping 0.2 mol Si, the as-synthesized Ti3Al1.0Si0.2C2 sample offers fine microstructure and has excellent performance. Its Vickers hardness, flexural strength and the fracture toughness are 5.52 GPa, 546 MPa, 7.51 MPa m1/2, respectively. The fracture mode is transgranular cleavage fracture. During propagation, the main crack deflects and branches obviously. The crack extends in a zigzag like path, accompanied by transgranular fracture. When suffering external force, the particular layered structure of Ti3(Al,Si)C2 can absorbs and dissipates more energy through hybrid deformation modes such as extrusion, kink, fold, interlaminar separation and tearing. With this complex and mixed fracture mode, the crack propagation were effectively prevented, and its flexural strength and fracture toughness were enhanced.

The temperature-dependent (T-dependent) linewidth (ΓG) and frequency shift (ΔωG) of the G mode provide valuable information on the phonon anharmonicity of graphene-based materials. In contrast to the negligible contribution from electron-phonon coupling (EPC) to the linewidth of a Raman mode in semiconductors, ΓG in pristine graphene is dominated by EPC contribution at room temperature due to its semimetallic characteristics. This leads to difficulty in resolving intrinsic contribution from phonon anharmonicity to ΓG. Here, we probed the intrinsic phonon anharmonicity of heavily-doped graphene by T-dependent Raman spectra based on FeCl3-based stage-1 graphite intercalation compound (GIC), in which the EPC contribution is negligible due to the large Fermi level (EF) shift. The ΔωG and ΓG exhibit a nonlinear decrease and noticeable broadening with increasing temperature, respectively, which are both dominated by phonon anharmonicity processes. The contribution of phonon anharmonicity to ΓG of heavily-doped graphene decreases as the EF approaches to the Dirac point. However, the T dependence of ΔωG is almost independent on EF and qualitatively agrees with the theoretical result of pristine graphene. These results provide a deeper understanding of the role of phonon anharmonicity on the Raman spectra of heavily doped graphene.

We investigate transient nanotextured heterogeneity in vanadium dioxide (VO2) thin films during a light-induced insulator-to-metal transition (IMT). Time-resolved scanning near-field optical microscopy (Tr-SNOM) is used to study VO2 across a wide parameter space of infrared frequencies, picosecond time scales, and elevated steady-state temperatures with nanoscale spatial resolution. Room temperature, steady-state, phonon enhanced nano-optical contrast reveals preexisting "hidden" disorder. The observed contrast is associated with inequivalent twin domain structures. Upon thermal or optical initiation of the IMT, coexisting metallic and insulating regions are observed. Correlations between the transient and steady-state nano-optical textures reveal that heterogeneous nucleation is partially anchored to twin domain interfaces and grain boundaries. Ultrafast nanoscopic dynamics enable quantification of the growth rate and bound the nucleation rate. Finally, we deterministically anchor photoinduced nucleation to predefined nanoscopic regions by locally enhancing the electric field of pump radiation using nanoantennas and monitor the on-demand emergent metallicity in space and time.

Traditional ferrites are of poor electromagnetic wave (EMW) absorption while doping rare earth elements (REEs) can greatly enhance their permeability to improve the EMW loss performance. In this study, Co-Zn ferrite nanoparticles doped with various amounts of REEs (Gd3+, Nd3+ and Pr3+) were synthesized by a hydrothermal method, and their particle morphology and an EMW absorption performance were characterized by using transmission electron microscopy (TEM) and a Vector network analyzer (VNA). The results show that the initial spherical Co-Zn ferrite nanoparticles present an irregular quadrilateral structure after Gd3+ doping, and the average particle size of Co0.5Zn0.5−xGdxFe2O4 increases from 26 to 50 nm with x increasing from 0 to 0.35. At x of 0.25, the reflectivity absorbance achieves −27.94 dB at 18 GHz with the effective absorption bandwidth (EAB) of 4.08 GHz at a sample thickness of 2.5 mm. When Nd3+ doping amount reaches x = 0.3, the minimum reflection loss (RL) is −25.63 dB at 18 GHz and EAB is 3.91 GHz. Doping Pr3+ (x = 0.25) in the sample broadens EAB, and the minimum RL is −16.1 dB at 16.81 GHz and EAB is 7.31 GHz. This study shows that the magnetic moment produced by doping REES can form magnetic domains, which affects the incident EMW and improves the magnetic loss. It is expected that REEs-doped Co-Zn ferrite nanoparticles can be used as efficient electromagnetic shielding materials in aerospace.

This study develops an atomistic simulation-based methodology for studying the dispersed droplet phase in immiscible alloy. The methodology is applied to the immiscible Al–Pb alloy liquid droplet system to study the temperature and curvature effects on the droplet radial distributions of thermodynamic properties, the mutual miscibilities within the spherical droplets, and the pressure differences across the curved liquid–liquid interfaces. The pressure tensor components profiles along radial direction are computed by the Irving–Kirkwood method coupling the spherical coordination and providing the inner droplet pressure data with sufficient statistical precision to validate the generalized Laplace equation in a liquid immiscible alloy system (both Al-rich convex droplet interface and Pb-rich concave droplet interface). Noticeable changes in mutual miscibilities in the droplet phases are seen, which correspond to the shifts of the solvus lines toward lower solubilities as temperature increases or the droplet size decreases. Compared with spherical droplets under the same temperature, cylindrical droplets with the same radii own the same Laplace pressure dependence of the mutual miscibilities but a weaker capability to tune the nano-alloy droplet phase diagram. Current findings contradict the miscibility changes in the two-complexion equilibria within the monoatomic layer at the Al(111)–Pb(liquid) interface [Acta Mater 2018;143:329]. The combined simulation-characterization methodology proposed in this study applies to broader types of immiscible alloy. The calculated data could provide guides to design well-dispersed droplet phases in the immiscible alloys and their manufacturing processes, facilitate the development of the thermodynamic theory/modeling of the nano-sized alloy phase diagram.

Although solid-state lithium (Li)-metal batteries promise both high energy density and safety, existing solid ion conductors fail to satisfy the rigorous requirements of battery operations. Inorganic ion conductors allow fast ion transport, but their rigid and brittle nature prevents good interfacial contact with electrodes. Conversely, polymer ion conductors that are Li-metal-stable usually provide better interfacial compatibility and mechanical tolerance, but typically suffer from inferior ionic conductivity owing to the coupling of the ion transport with the motion of the polymer chains1–3. Here we report a general strategy for achieving high-performance solid polymer ion conductors by engineering of molecular channels. Through the coordination of copper ions (Cu2+) with one-dimensional cellulose nanofibrils, we show that the opening of molecular channels within the normally ion-insulating cellulose enables rapid transport of Li+ ions along the polymer chains. In addition to high Li+ conductivity (1.5 × 10−3 siemens per centimetre at room temperature along the molecular chain direction), the Cu2+-coordinated cellulose ion conductor also exhibits a high transference number (0.78, compared with 0.2–0.5 in other polymers2) and a wide window of electrochemical stability (0–4.5 volts) that can accommodate both the Li-metal anode and high-voltage cathodes. This one-dimensional ion conductor also allows ion percolation in thick LiFePO4 solid-state cathodes for application in batteries with a high energy density. Furthermore, we have verified the universality of this molecular-channel engineering approach with other polymers and cations, achieving similarly high conductivities, with implications that could go beyond safe, high-performance solid-state batteries. By coordinating copper ions with the oxygen-containing groups of cellulose nanofibrils, the molecular spacing in the nanofibrils is increased, allowing fast transport of lithium ions and offering hopes for solid-state batteries.

It is generally accepted that the interface effect and surface electronic structure of catalysts have vital impact on catalytic properties. Understanding and tailoring the atomic arrangement of interface structure are of great importance for electrocatalysis. Herein, we proposed a simple method to synthesize etching-PtNiCu nanowires (e-PtNiCu NWs) enclosed by both (110) and (100) facets evolving from PtNiCu nanowires (PtNiCu NWs) mainly with (111) facets by selectively etching process. After acetic acid etching treatment, the e-PtNiCu NWs possess high total proportions (88.3%) of (110) and (100) facets, whereas the (111) facet is dominant in PtNiCu NWs (64%) by qualitatively and quantitatively evaluation. Combining the structure characterizations and performance tests of ethanol electrooxidation reaction (EOR), we find that the e-PtNiCu NWs display remarkably performance for EOR, which is nearly 4.5 times and 1.5 times enhancement compared with the state-of-the-art Pt/C catalyst, as well as 2.2 and 1.4 times of PtNiCu NWs, in specific activity and mass activity, respectively. The improved performance of e-PtNiCu NWs is attributed to synergistic catalytic effect between (110) and (100) facets that not only significantly decreases the onset potentials of adsorbed CO (COads) but also favors the oxidation of COads on the surface of catalyst. Furthermore, thermodynamics and kinetic studies indicate that the synergistic effect of both (110) and (100) facets in e-PtNiCu NWs can decrease the activation energy barrier and facilitate the charge transfer during the reaction. This work provides a promising approach to construct catalysts with tunable surface electronic structure towards efficient electrocatalysis.

The effect of freeze-thaw cycles on the axial tension and axial compression properties of completely carbonized concrete are investigated in this study. Three grade concrete specimens (C30, C40, and C45) were fabricated. The freeze-thaw cycle test was carried out on the completely carbonized specimens, followed by axial tension and axial compression tests. The results show that completed carbonization increases the axial tensile peak stress of C30, C40, and C45 concrete specimens by 8.7%, 9.7%, and, 12.1%, respectively. The peak axial tension strain increased by 1.9%, 7.2%, and 9.6%, respectively. The peak axial compressive stress increased by 10.5%, 19.1%, and 24.1%, respectively. The peak axial compressive strain decreased by 13.7%, 14.1%, and 14.3%, respectively. With the increase of freeze-thaw cycles, the peak stress of tensile stress, peak strain, and compressive stress of concrete decrease continuously. The peak strain of compressive strain increases. The lower the strength grade of concrete, the faster the decline rate of stress and strain. According to the data changes of peak stress and peak strain at different times of freeze thaw after carbonization, the stress-strain curve fitting formula for concrete under freeze-thaw cycles after complete carbonization is put forward, which has a good coincidence with the experimental result.

The development of kesterite photovoltaic solar cells has been hindered by large open-circuit voltage (Voc) deficit. Recently, SnZn deep point defect and associative defect cluster have been recognized as the main culprit for the Voc losses. Therefore, manipulating the deep-level donor of SnZn antisite defects is crucial for breaking through the bottleneck of present Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic technology. In this study, the SnZn deep traps in CZTSSe absorber layer are suppressed by incorporation of Ge. The energy levels and concentration of SnZn defects measured by deep-level transient spectroscopy (DLTS) decrease significantly. In addition, the grain growth of CZTSSe films is also promoted due to Ge implantation, yielding the high quality absorber layer. Consequently, the efficiency of CZTSSe solar cells increases from 9.15% to 11.48%, largely attributed to the 41 mV Voc increment.

Understanding the transport behavior of a gel system in porous media is of great significance in enhancing oil recovery (EOR) for high water cut oil reservoirs. However, the length of the experiment models (sandpack or core sample) in current studies is usually in the range of centimeter scale, which is too short to track the full movement path of gel particles. In this work, 10-m long slim sandpacks were adopted to conduct gel flooding experiments. The pressure and polymer concentration distribution along the sandpack was tracked, and scanning electron microscope (SEM) technique was employed to observe the pore morphology after the gel flooding. The results show that the movement of polymer particles is usually within 7 m away from the inlet due to the adsorption and retention in the porous medium. For 0.4 PV injection cases, SEM images show that the pore morphology at the inlet region exhibits a stable polymer network, while the network structure disappears at the outlet, along with the decrease of fluid viscosity from 620.1 mPa·s to 1.2 mPa·s. However, we can still find the stringy state polymer after 5 m movement and the viscosity is 584.0 mPa·s for 1 PV gel injection cases. Four characterization parameters, including equivalent viscosity, breakthrough pressure gradient, dimensionless gelation gradient, and plugging ratio, were proposed to quantitatively characterize the performance of gel flooding. In addition, empirical models were also obtained to predict the four parameters through multi-parameters fitting, and these models facilitate the characterization of the gel flooding performance. This is the first work, to the best of the authors’ knowledge, using long slim sandpack (10 m) to experimentally study gel system transport in porous media, which provides theoretical implications in enhancing oil recovery.

In this work, a new kind of butterfly-like molecules of oxacalix[2]arene[2]pyrazine (OAP) are reported, which exhibit typical characteristics of aggregation-induced emission (AIE) via the restriction of intramolecular vibration (RIV) mechanism. Unlike any of the reported RIV-type AIE molecules, the synthetic procedures of which are complicated and associated high costs, OAP AIEgens can be synthesized in a facile manner by a one-step catalyst-free reaction using commercially available materials. Notably, OAP AIEgens are ideal ligands for constructing metal-organic frameworks (MOFs) due to their built-in coordination sites of pyrazine groups. OAP-based MOFs exhibit multiple potential applications in reversible gas response, encrypted information storage, and construction of white light-emitting devices. This work enriches limited kinds of RIV-type AIEgens, offers additional selections of bridging ligands for constructing luminescent MOFs and provides a visualized prototype to understand the effect of RIV process on the luminescence property of MOFs.

In order to investigate the influence of water content on the damage and degradation characteristics of Hutubi sandstone, different saturation experiments and laboratory mechanical experiments were carried out on Hutubi sandstone. The experimental results show that under uniaxial and triaxial conditions, with the increase in water content, the axial, lateral, and volume deformations gradually increase, and the deformation shows obvious dilatancy characteristics. The deviator stress and elasticity modulus of the sandstone decreased exponentially with the increasing water content. Confining pressure has a significant effect on the strength improvement of sandstone under the constant water content. Based on lognormal distribution, the damage constitutive model of sandstone which can reflect both uniaxial and triaxial condition with different water contents was proposed. The theoretical curves were compared with the experimental curves, and it was found that the theoretical curves and the experimental curves have similar changing trends. It shows the rationality of the statistical damage constitutive model.

Based on three-dimensional (3D) general solutions for one-dimensional (1D) hexagonal piezoelectric quasicrystals (PEQCs), this paper studied the frictional contact problem of 1D hexagonal PEQCs layer. The frequency response functions for 1D hexagonal PEQCs layer are analytically derived by applying double Fourier integral transforms to the general solutions and boundary conditions, which are consequently converted to the corresponding influence coefficients. The conjugate gradient method is used to obtain the unknown pressure distribution, while the discrete convolution–fast Fourier transform technique is applied to calculate the displacements and stresses of phonon and phason, electric potentials and electric displacements. Numerical results are given to reveal the influences of layer thickness, material parameters and loading conditions on the contact behavior. The obtained 3D contact solutions are not only helpful for further analysis and understanding of the coupling characteristics of phonon, phason and electric field, but also provide a reference basis for experimental analysis and material development.

ZnS has great potentials as an anode for lithium storage because of its high theoretical capacity and resource abundance; however, the large volume expansion accompanied with structural collapse and low conductivity of ZnS cause severe capacity fading and inferior rate capability during lithium storage. Herein, 0D-2D ZnS nanodots/Ti3C2Tx MXene hybrids are prepared by anchoring ZnS nanodots on Ti3C2Tx MXene nanosheets through coordination modulation between MXene and MOF precursor (ZIF-8) followed with sulfidation. The MXene substrate coupled with the ZnS nanodots can synergistically accommodate volume variation of ZnS over charge–discharge to realize stable cyclability. As revealed by XPS characterizations and DFT calculations, the strong interfacial interaction between ZnS nanodots and MXene nanosheets can boost fast electron/lithium-ion transfer to achieve excellent electrochemical activity and kinetics for lithium storage. Thereby, the as-prepared ZnS nanodots/MXene hybrid exhibits a high capacity of 726.8 mAh g−1 at 30 mA g−1, superior cyclic stability (462.8 mAh g−1 after 1000 cycles at 0.5 A g−1), and excellent rate performance. The present results provide new insights into the understanding of the lithium storage mechanism of ZnS and the revealing of the effects of interfacial interaction on lithium storage performance enhancement.

Combination of anionic doping and multicomponent synergism are effective approach to improve the performance of electrocatalysts toward hydrogen evolution reaction (HER) process. Herein, P-doped CoS2–MoS2 hollow spheres assembled by countless sheets on oxidized Mo foil (P–CoS2/MoS2/MoO2) was synthesized by hydrothermal and phosphorization process. The unique hollow structure with countless sheets as wall endows more accessible active sites, fast electron/mass transport and high conductivity. P-doping could redistribute the local charge density and optimize the surface charge state to improve the intrinsic activity and accelerate reaction kinetics. The optimized P–CoS2/MoS2/MoO2 exhibits an outstanding HER performance with an overpotential of 85 mV to reach 10 mA cm−2, a small Tafel slope of 84.6 mV dec−1, superior intrinsic HER activity and robust durability under alkaline solution. This work proposed a feasible strategy to build the hollow, heterostructured and binder-free electrode in renewable energy application.

Transparent conductive oxide (TCO) semiconductors are attracted considerable attention due to a wide range of applications, such as flat panel display (FPD), touch panels, solar cells, and other optoelectronic devices. Owing to the different carrier conduction paths between n-type and P-type TCOs, the n-type TCO used in TFTs usually have high Ion/Ioff current ratio (>107) and high electron mobility (>10 cm2/V·s), P-type TCO TFTs are both lower than that of n-type one. For complementary circuits design and applications, however, both P-type and n-type semiconductor materials are equally important. For SnO thin films, it is important to adjust the ratio of Sn2+ (SnO P-type) and Sn4+ (SnO2 n-type) in order to modulate the electrical characteristics. In this investigation of post treatment for SnO thin films, both microwave annealing (MWA) and furnace annealing process with 02 ambient are studied. The results show that SnO thin films are optimized at 300 °C, 30 minutes furnace annealing, the P-type SnO/SnO2 thin film shows surface mean roughness 0.168 nm, [Sn2+]/[Sn4+] ratio as 0.838, at least 80% transmittance between 380 nm-700 nm visible light. Withthe results, SnO can be even used to fabricate high performance P-type thin film transistors (TFTs) device for future applications.

Fabricating supported metal catalysts from layered double hydroxides (LDHs) is a promising strategy to develop high-efficient and low-cost materials for water detritiation. In this work, a series of NiAl-LDHs with different Ni/Al ratios were prepared and reduced to obtain Ni-based catalysts with Al2O3 support (Nix-Al2O3) and further tested in vapor phase catalytic exchange (VPCE) process. Results revealed that the activity of catalysts varies with Ni/Al molar ratios and is also affected by textural properties. Remarkably, the Ni2–Al2O3 with the Ni/Al molar ratio of 2 exhibited excellent activity, due to the balanced factors of Ni content, specific surface area, Ni particle size and Al3+ configuration proportion. This study sheds some light on reaction mechanism of VPCE process and may be applicable for the rational design of highly efficient catalysts.

YBa2Cu3O7− x (YBCO) is treated as a high-temperature superconductor material for its excellent performance. In this article, we investigated the superconducting properties of YBCO grown on LaAlO3 (LAO) substrate with Eu0.6Sr0.4BiO3 (ESBO) buffer layers. Though the chemical solution-based method, we get ESBO buffer with tetragonal SrO2 particles precipitated on the surface. The cross section of transmission electron microscopy shows more microstructure details of defects of YBCO films introduced by buffer layers and self-assembled SrO2. It is observed that the critical current density Jc of YBCO grown with buffer layers enhanced approximately 40% compared with those on LAO at a low applied magnetic field. The comparison of fitted curves of YBCO/ESBO with different pinning types shows that it is closer to δl pinning and began to lean to δ stress pinning with temperature arise. The values of pinning forces also get improved. Besides, the analysis of normalized pinning force density at 77 K demonstrates the interplay of different flux pinning mechanisms. Finally, all the results show the effectiveness of ESBO buffer layers on enhancing the performance of YBCO.

Cellulose esters (CEs) are promising biodegradable substitutes for traditional petroleum-based plastic materials. Research on structure–property relationships of CEs is necessary to evaluate their suitability for industrial applications such as food packaging. Cellulose esters with different side-chain lengths were synthesized and studied. Their thermal and moisture barrier properties were characterized. Cellulose triheptanoate (CTH) was proved to have an optimal moisture barrier (WVTR = 0.31 g·mil/day/in.2) and was used to blend with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactic acid (PLA) bioplastics. CTH addition improved the PLA thermal stability, enhanced the ductility, and increased the moisture barrier by 32%, while it decreased the PHBV thermal stability, weakened the ductility, and reduced the moisture barrier by 90%. We demonstrated that by proper choice of the combination of CE and bioplastic, bioplastic blends with unique and useful synergistic properties can be obtained. These blends can potentially be used for commercial applications, such as biodegradable flexible packaging.

Oxygen evolution reaction (OER) plays an indispensable role in developing renewable clean energy resources. One of the critical bottlenecks for the reaction is the development of highly efficient electrocatalyst to decrease the high overpotentials of four-electron transfer process of OER. Recently, layered double hydroxides (LDHs) have been widely investigated among the most promising electrocatalysts for OER due to their high intrinsic activity, excellent stability as well as low-cost. However, it remains unclear how the exposed facet of the LDHs affects their electrocatalytic activity. Here we elucidate the active edge facet of LDHs towards OER by combining the finely control of edge facet ratio coupled with molecular probe method and computational calculation. The LDHs with higher edge facet area ratio show superior activity with low onset potential as well as decreased Tafel slope. The active edge site is further proved by blocking the unsaturated edge sites with cyanate probe anion, of which the adsorption largely inhibits OER activity. Furthermore, based on density functional theory (DFT) calculation, two-dimensional map of theoretical overpotentials as a function of Gibbs free energy reveals that the edge (100) facet exhibits a much higher OER activity than basal plane (001) facet.

In this article, nickel (Ni) coating was constructed on brass substrate by a simple electrodeposition technique, and myristic acid/TiO2 composite (MTC) modifier was used to modify Ni coating. The chemical composition and surface morphology of MTC confirm that myristic acid (MA) was successfully grafted on TiO2 nanoparticles. As a comparison, the structures of the Ni coatings were modified by MTC or MA. We found that both modified Ni coatings exhibit strong durability, self-cleaning and superhydrophobicity ability and have good prospect of decontamination. After Ni coating had been modified by MTC, the water contact angle and sliding angle of MTC-Ni were > 170° and < 5°, respectively. In addition, the MTC-Ni coating shows improved corrosion resistance, which can effectively retard the corrosion of brass. This novel and facile electrodeposition-modification route is believed to be widely applied to preparing superhydrophobic surfaces on metallic materials.