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Enhancing damping characteristic is one of the effective methods to solve the instability problem of the rotor system. The three-dimensional numerical analysis model of scallop damper seal was established, and the effects of inlet pressures, preswirl ratios, rotational speeds, interlaced angles and seal cavity depths on the rotordynamic characteristics of scallop damper seal were studied based on dynamic mesh method and multi-frequencies elliptic whirling model. Results show that the direct stiffness of the scallop damper seal increases with decreasing inlet pressure and increasing rotational speed and cavity depth. When the seal cavity is interlaced by a certain angle, which shows positive direct stiffness. The effective damping of the scallop damper seal increases with the increasing inlet pressure, the decreasing preswirl ratio and the rotational speed and cavity depth. There exists an optimal interlaced angle to maximize the effective damping and the system stability. The leakage of the scallop damper seal is significantly reduced with decreasing inlet pressure. The preswirl will reduce the leakage flowrate, and the rotational speed has a slight effect on the leakage performance. The leakage of the scallop damper seal decreases with increasing seal cavity depth.

Ultrafast optical spin control allows gate operations to be performed within a picosecond timescale, orders of magnitude faster than microwave or electrical control. Here, using high-level quantum chemical computations, we suggest a two-qubit logic gate based on the optically induced ultrafast spin-flip and spin-transfer processes over rhombic graphene nanoflakes (Co4-GNF). It is demonstrated that the π-conjugated Co atoms can significantly influence the spin properties of the system. The spin density is distributed on different Co atoms in different energy levels, in this way opening a channel for successful spin-transfer processes between the Co atoms. Thus, the reversible local spin-flip processes on each Co atom and global spin-transfer processes between the Co atoms are realized. Importantly, based on various spin-dynamics processes achieved in Co4-GNF structures, both classical (OR, AND, NAND) and quantum (CNOT, SWAP) two-qubit logic gates are constructed, and the spin manipulation process can be completed in subpicosecond timescale with fidelity above 96%. This theoretical design based on the laser-induced ultrafast spin dynamics provides a new implementation of qubit manipulation, which could pave the way towards the construction of nano magnetic logic circuits and spintronic devices.

A PT-SWCNTs self-assembled nanorobot is proposed to release residual H2 based on adhesion competition in a SWCNT system.

Composites made from multi-walled carbon nanotubes and polydimethylsiloxane exhibit an excellent piezoresistivity at elastic limits where strain sensitivity reaches 0.93–0.96 and resistance changes due to stretching and compressing matches with loading histograms. Resistance change becomes pulse-like as the samples are bent and/or twisted, attributed to the rapid increase in intertube spacing. Straining induces movements and segmentations of tube aggregates with tube mobility ranging at 0.1–90 nm/s. Intertube barrier driven sensing mechanism is viscoelasticity related and is therefore interpreted on the basis of spring-dashpot models.

Based on reactive air brazing (RAB), we designed a new type of sealant (Ag–xCuAlO2) for joining 3 mol.% yttria-stabilized zirconia (YSZ) ceramics and AISI 310S stainless steel. The CuAlO2 content affected the wettability of the sealant on the YSZ surface, and the joints had a high shear strength when Ag–2 wt.%CuAlO2, which had a small contact angle on the YSZ substrate, was used as the sealant. In addition, the thickness of the oxide layer was reduced compared to that for the Ag–CuO sealant. The effects of the processing parameters on the microstructure and shear strength of the joints were investigated, and the as-brazed joints reached their highest shear strength (93.7 MPa) when brazed at 1040 °C for 30 min. After high-temperature oxidation at 800 °C for 200 h, the shear strength of the joints remained at 50 MPa, and no apparent change in the microstructure was observed, proving that the joints possessed excellent oxidation resistance.

Due to the formation of excessive brittle compounds, the joint of Cf/C composites and single crystal Ni-based superalloy (DD3) has relatively low mechanical properties, greatly degrading the reliability of joints. In this work, an active Cu interlayer is introduced to adjust the interfacial reaction and microstructure of the joint. Effects of the Cu interlayer on the interfacial reaction and microstructure of joints are investigated in detail. Especially, the effect of the Cu interlayer on the joining stability of the joint is first analyzed, and its enhancement mechanism is further clarified. Adding an active Cu interlayer prevents the intense diffusion of Ni and Al from the DD3 side to the Cf/C side by a reactive adjusting process. Therefore, brittle AlNi2Ti phases only can be formed in the region nearby the DD3. Besides, the content of the Cu solid solution in the brazed seam is increased, significantly improving the plastic deformation ability of the joint. The maximum shear strength of Cf/C-DD3 joints with the Cu interlayer reaches to 54 MPa, approximately 50% higher than that of the joint without the Cu interlayer. Furthermore, a stable joint strength is obtained in a broader brazing temperature range from 880 °C to 940 °C.

Rock cracking caused by thermal shocking occurs widely in geothermal exploitation processes, such as wellbore drilling, reservoir stimulation, and long-term geothermal extraction. In this study, the permeability, P-wave velocity, uniaxial compressive strength, and tensile strength of granite subjected to heating (100 ~ 300℃) and cooling in water with different temperatures (0 ~ 60℃) were experimentally investigated. Moreover, the evolution of temperature field, cooling rate, and temperature gradient inside the samples during rapid cooling were tested. The results show that a decrease in the temperature of the cooling water aggravates the deterioration of the physical and mechanical properties of the granite after rapid cooling; this deterioration is specifically manifested in the increase in permeability and the decrease in P-wave velocity and mechanical strength of the granite samples. The heat transfer mechanism of the high-temperature granite under rapid cooling is characterized by unsteady heat conduction. The evolution of the internal temperature, cooling rate, and temperature gradient of the granite samples with time can be divided into three stages: the first 200s is the rapid cooling stage; 200s ~ 400s is the slow cooling stage; 400s ~ 600s is the temperature basically constant stage. The evolution of the cooling rate and temperature gradient formed in the high-temperature granite specimens under rapid cooling is consistent, and they all show a trend of rapid increase first followed by a slow decrease. The maximum values of the cooling rate and temperature gradient always appear in the area near the outer surface, which is closest to the solid–liquid heat exchange interface. This study has potential guiding significance for the application of rapid cooling in the development of enhanced geothermal system.

A series of Lu3+, Tb3+: CeF3 nanoparticles were successfully prepared via the hydrothermal method. The results show that the nanoparticles exhibit obvious green emission after being effectively doped with Tb3+ ions, and the luminous intensity further increases with the increase of Lu3+ doping concentration. Hysteresis loops show that the magnetic susceptibility of Lu3+, Tb3+: CeF3 nanoparticles is 0.1310 emu/g under a magnetic field of 10,000 Oe. These proof-of-concept results show that Lu3+, Tb3+: CeF3 nanoparticles can be widely used in many important fields. It provides a theoretical basis for the combination of luminescent and magnetic properties of nanoparticles.

Highly transparent leafhopper (Thaia rubiginosa) wings are self-decorated with embroidered ball-shaped proteinaceous brochosmoes as distinct anti-predator defenses. The non-sticky brochosomal coating serves as antireflective structures for camouflage in vegetated environments. Inspired by the leafhopper wings, this study reports a new type of reversible antireflection coating enabled by integrating self-assembly methodologies using a shape memory polymer. The resulting embroidered ball-like structure array establishes a refractive index transition on surface, and thereby behaves omnidirectional antireflective characteristics in a broadband visible light region. Interestingly, the highly transparent appearance can be instantly erased and recovered by submerging in common liquids, such as water and ethanol, or by applying contact pressures at ambient conditions. Furthermore, the reversibility and structure-shape effect on the antireflective characteristics are systematically evaluated in this study.

Bacterial infections prolong the wound healing time and increase the suffering of patients, thus it is important to develop wound dressing that can inhibit bacterial infection. Herein, we use two methods including “doping method” and “secondary growth method” to prepare ZIF-8@gentamicin embedded in and coated on polyacrylonitrile/gelatin (PG) nanofibers, separately. Composite nanofibers prepared by the secondary growth method achieve higher drug loading than that of the doping method, and the release rate can be adjusted by pH. Simultaneously increasing drug loading and regulating its release rate are achieved in the secondary growth method, which cannot be achieved by the doping method. Furthermore, synergistic antibacterial property occurs in the composite nanofibers prepared by the secondary growth method, and gentamicin loaded on ZIF-8 promotes the antibacterial effect, which shows better antibacterial effect than the doping method. As a result, during the wound infection of mouse, composite nanofibers prepared by the secondary growth method exhibit a faster recovery effect than the doping method, which effectively shortened the wound healing time from 21 days to 16 days.

Abstract Under multi-wheel heavy load, the asphalt mixture is prone to exhibit the deformation superposition effect, which exacerbates the damage of pavement structure. Multi-point penetration tests and numerical simulations by discrete element method (DEM) are performed to investigate the deformation superposition effect and micromechanical characteristics of asphalt mixture. The effect of wheel spacing, wheel group, and the evolution of micromechanical deformation superposition behavior are analyzed. Results indicate that the deformation superposition resistance of the asphalt mixture under the multi-wheel load decreases dramatically with the decrease in wheel spacing and the increase in the number of wheels, specifically the wheel spacing is 54 mm and the number of wheels is 4. The DEM simulations reflect the micromechanical property of asphalt mixture in the multi-point penetration test. The reduction of tensile chains is the internal reason for asphalt mixture deformation superposition, indicating the decrease of the adhesive strength of the material. A remarkably positive correlation is found between the reduction of the tensile chain and the deformation effect coefficient. In the process of superposition, the aggregate skeleton force chains are gradually destroyed and decrease to zero until cracking. The numerical simulation outcome is consistent with the laboratory penetration test outcome.

In this paper, a co-doped cubic phase submicron particles Ba2LaF7:Yb3+/Ln3+ (Ln = Er3+,Ho3+) up-conversion material were successfully synthesized by hydrothermal method. By adjusting PH, time, temperature, and the amount of sodium citrate during the preparation process, it was possible to analyze and obtain the phase structure, morphology, and up-conversion luminescence characteristics of the particles. Furthermore, the influence of doping concentration on the up-conversion luminescence characteristics was studied using X-ray diffractometer (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy, and other characterization methods. The test results show that, under the conditions of pH = 9 and NaBF4 as the fluorine source, Ba2LaF7:Yb3+/Ln3+ (Ln = Er3+,Ho3+) spherical particles have an average size of 240 nm. Under the excitation of a 980 nm laser-diode (LD) laser, it was found that the material spectrum is mainly composed of strong green and weak red light. When Yb3+ and Er3+ doping concentrations are 18% and 2.5%, Yb3+ and Ho3+ doping concentrations are 18% and 3.5%, respectively, the up-conversion transmittance is the highest. Finally, the possible causes of the fluorescence decay curve of Ba2LaF7:Yb3+/Ln3+ (Ln = Er3+,Ho3+) up-conversion materials were investigated.

A novel B2O3–Al2O3–SiO2 (BAS) glass filler was first developed to join Al2O3 and zirconia toughened alumina (ZTA) ceramics. The microstructure, crystallization products, and interfacial reaction layer of the joint were all studied. Detailed growth process and the microstructural evolution mechanism of aluminum borate (Al18B4O33 and Al4B2O9) crystal whiskers were revealed through controlling the joining temperature and the holding time. The results showed that the Al18B4O33 and Al4B2O9 whiskers formed at the interfaces and in the joining seam, owing to the reaction between the substrates and the BAS glass system, and the precipitation out of the glass, respectively. Finally, bonded with this BAS glass filler at 1400 °C for one hour, the joints exhibited a maximum shear strength of 42 MPa at room temperature and good mechanical performance after thermal cycling.

We report spinel-type CoFe2O4 nanocrystals (NCs) synthesized through facile hydrothermal growth and their attachment on a cage-like carbon (CC) for efficient and durable oxygen evolution/reduction reaction (OER/ORR) performance. As a catalyst, the so-constructed CoFe2O4 NCs show significantly higher OER performance than bare CoFe2O4 and CC, leading to an overpotential of 1.59 V for the OER at a current density of 10 mA/cm. Furthermore, CoFe2O4 NCs on CC electrodes also exhibit good ORR performance, which is comparable to Pt/C, significantly higher than that of bare carbon fiber paper, and acts as a bifunctional electrocatalyst. The CoFe2O4 NCs anchored on the CC electrodes exhibit remarkably long-term stability, which is evaluated by continuous cycling (over 5,000 cycles), without any morphological change, but preserving all the materials within the electrode. The results indicate that the CoFe2O4 NCs have a promising potential for efficient, cost-effective, and durable oxygen electrocatalysis at large scales using earth-abundant materials and low-cost fabrication processes.

The conventional fully partitioned pocket damper seal (FPDS) was improved by introducing several nozzles on the first seal tooth, which generates a reverse injection fluid suppressing the cavity flow in the circumferential direction. Computational fluid dynamics (CFD) models of the conventional FPDS and current novel FPDS were established. An infinitesimal theory was employed to identify the rotordynamic coefficient of the FPDS. The influence of nozzle types (negative, straight, positive), inlet/outlet areas, deflection angles (θ) on the rotordynamic performance was comprehensively analyzed. It was found that reducing the circumferential flow in the first seal cavity is crucial for increasing the stability of the FPDS. A negative nozzle angle can restrict the circumferential flow effectively and significantly improve the effective damping and system stability. The crossover frequency for the novel FPDS with θ = −10° is ∼62 Hz, which is much lower than that for the conventional FPDS (∼85 Hz). The increasing inlet/outlet area ratio of the nozzle can also enhance the seal stability. Increasing the negative nozzle angle (θ = none, −10°, −15°, −20°) can effectively increase the effective damping and reduce the crossover frequency from ∼85 Hz to ∼38 Hz. However, the novel FPDS with three kinds of nozzles shows a slight increase (< 2.5 %) in the leakage flow rate compared with the conventional FPDS.

Solid-state lithium batteries (SSLBs) based on garnet-type solid-state electrolytes (SSEs) have attracted much attention due to their high energy density and chemical stability. However, poor room-temperature ionic conductivity and low density of SSEs induced by conventional preparation routes limit their potential future applications. In this work, an oriented attachment strategy is employed to enhance the Li-ion conductivity and density of garnet-type SSE Li6.5La3Zr1.5Ta0.5O12 by introducing La2O3 nanoparticles. The oriented attachment of the ZrO2(Ta2O5) matrix mediates the epitaxial growth of the La-Zr(Ta)-O intermediate phase due to the addition of La2O3 nanoparticles. Continuous Li-ion transport pathways along grain boundaries are produced by the combination of residual La2O3 and gas Li2O. A densification interface is obtained when 10 wt % La2O3 is doped. The maximum value of Li-ion conductivity reaches 8.20 × 10-4 S·cm-1, with a relative density of 97.3%. SSLBs with a LiFePO4 cathode showing a stable cycling performance with a discharge capacity of 123.1 mA·h·g-1 and a Coulombic efficiency of 99.2% after 300 cycles (0.5C) at room temperature. This work is comparable to the state-of-the-art methodology, which provides a feasible approach to creating SSEs with high performances for SSLBs.

We introduced a novel strategy for direct joining Ti3AlC2 ceramics in air without the need for any interlayer and vacuum/ inert gas protection. This was achieved by applying constant external pressure to manipulate the amount of available oxygen for oxidation at the Ti3AlC2―Ti3AlC2 interface. The shear strength of the joints bonded under a pressure of 10 MPa was approximately 3 times higher than that without pressure. The joining mechanisms were addressed based on the atomic interdiffusion and preferential oxidation of Al in lamellar Ti3AlC2 grains.

In this paper, the preparation of a series of Li2TiGe1−xCrxO5 phosphors by high-temperature solid-state reaction is reported. The results of X-ray diffraction show that the doping of Cr4+ ions makes the lattice expand to a larger size. X-ray photoelectron spectroscopy analysis shows that the chromium ions in the sample are tetravalent, confirmed further by fluorescence spectroscopy. Under the excitation of 980 nm laser, the Cr4+ ions 3T2 → 3A2 radiates transition and emits light at 1300 nm. At the same time, the luminescence lifetime decreases with the increase in Cr4+ ions doping concentration. Li2TiGe1−xCrxO5 phosphors have a broad application prospect in near-infrared LEDs.

It is usually necessary to first perform temperature reduction treatment to enable the catalyst to exert its catalytic activity in the subsequent process of preparing carbon nanotubes by chemical vapor deposition. In this experiment, Fe-Mo/Al2O3 catalyst was prepared based on microreactor, and the effect of reduction temperature on the microstructure of the catalyst and the morphology of carbon nanotubes was investigated. The results show that the reduction temperature has a significant effect on the microstructure of the catalyst, which in turn affects its catalytic activity and the yield and quality of carbon nanotubes. Moderately reducing the reduction temperature during the catalyst reduction process is beneficial to increase the catalytic activity of the catalyst. However, although its sintering degree could be weakened when the catalyst was reduced at an excessively low temperature of 350 °C, its catalytic efficiency was greatly reduced and the degree of defects of the catalyzed carbon nanotubes was increased. When the catalysts calcined at 450 °C and reduced at 600 °C, the catalysts show excellent catalytic activity, and catalytic efficiency can reach 74.76%. In addition, the reduction temperature also has a certain effect on carbon nanotubes. As the reduction temperature increases, the span of carbon nanotubes is relatively concentrated, but the specific gravity of the thicker outer diameter gradually increases. As for the defect degree of carbon nanotubes, the carbon nanotubes M600-600 is better and the defects are fewer when the reduction temperature is reduced from 670 °C to 600 °C.

Graphene(Gr) reinforced copper matrix composites(Gr/Cu) were prepared by powder metallurgy process, and the effects of graphene content on microstructure and properties of the composites were investigated. The microstructure, density, hardness and electrical conductivity of the composites were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), density measurement, hardness tester and conductivity meter. The results show that the interface bonding of the composite is good, there is no crack and no obvious interface reaction; there are a lot of dislocations and twins in Cu matrix. With the increase of graphene content, the density, heat capacity and thermal conductivity of the composites decrease, but the hardness increases first and then decreases.

In this article, a slow wave (SW) ridged half-mode substrate integrated waveguide (RHMSIW) combined with spoof surface plasmon polaritons (SSPPs) structure is proposed. The SW feature is achieved by integrating the SSPP structure into the metal ridge of RHMSIW. Besides, the proposed structure has a compact lateral size because the ridge of the RHMSIW introduces a step capacitance in the waveguide. Due to the loading of the SSPP structure, the proposed RHMSIW-SSPP structure has the ability of strong electric field confinement. Compared with the RHMSIW structure, the proposed RHMSIW-SSPP structure has a low crosstalk feature. A prototype of the proposed RHMSIW-SSPP structure with band-pass 4.5–14 GHz is designed and fabricated under PCB process. The proposed RHMSIW-SSPP structure reduces the longitudinal size over 50% and the lateral width by 40% compared with the HMSIW, and reduces the longitudinal size over 50% and the transverse width by 70% compared with the SIW. Therefore, the proposed structure has potential applications in miniaturized microwave and RF systems.

In order to increase the energy density of lithium-ion battery, the LiNi0.8Co0.1Mn0.1O2(NCM811) cathode material with higher Ni content has attracted much attention due to its advantages such as high energy density, low cost. However, there are some bottleneck problems about the NCM811 such as capacity fading, harsh storage conditions, poor thermal stability, poor safety, which limit its large-scale commercial use. This article reviews the urgent problems for NCM811 high nickel ternary materials, briefly describes several common synthesis methods, and focuses on the modification methods, such as element doping, surface coating and special core-shell structure for enhancing the electrochemical performances and explain the modification mechanism. Finally, we prospect the possible research development and commercial application of high nickel ternary material.

In this study, hydrothermal synthesis of CeF3: Tb, Gd nanoparticles doped with Li+ alkali metal ions were demonstrated using introduction of Li+ ions through LiNO3 nitrate. These nanoparticles have dual properties of magnetic fluorescence. X-ray diffraction, Fourier transform infrared spectrometer, XPS and photoluminescence spectra, and vibrating sample magnetometry were used to characterize structural properties, surface functional groups, fluorescence, and magnetic properties of these particles. Results show that CeF3: Tb, Gd nanoparticles exhibit bright green light emission under excitation at 258 nm and 378 nm ultraviolet band. Through the modification of Li+ ions, luminous intensity of green light is further improved. Energy transfer between rare earth ions was investigated via photoluminescence spectroscopy. This work demonstrates potential applications of Li doped CeF3: Tb, Gd nanoparticles as photomagnetic dual-functional materials in fields of biological imaging, solid state lighting, and magnetic biological separation.

A novel salt-inclusion fluoroiodate [GaF(H2O)][IO3F] derived from CsIO2F2 was ingeniously obtained through anisotropic polycation substitution. Because the catenulate [GaF(H2O)]2+ framework serves as a template for the favorable assembly of the polar [IO3F]2− groups and contributes to the nonlinear coefficient, [GaF(H2O)][IO3F] exhibits a greatly improved second-harmonic generation (SHG) effect of 10 times that of KH2PO4 (KDP) and a considerable band gap of 4.34 eV compared to the parent compound CsIO2F2 (3 × KDP, 4.5 eV). Particularly, to the best of our knowledge, [GaF(H2O)][IO3F] has the largest laser-induced damage threshold (LDT) of 140 × AgGgS2 of the reported iodates. All these results signify that [GaF(H2O)][IO3F] is a promising nonlinear optical (NLO) crystal. This work also proposes that anisotropic polycation substitution is an effective approach to optimize the SHG effect and develop excellent NLO materials., A novel salt-inclusion fluoroiodate nonlinear optical material, [GaF(H2O)][IO3F], is derived from CsIO2F2 through polycation substitution, and it exhibits an intense SHG effect of 10 times that of KH2PO4 and improved overall performance.

In this article, a ridged substrate integrated coaxial line (RSICL) is proposed, which has a compact size, wide bandwidth, and excellent shielding. The RSICL has two ridges set on both sides of its outer conductor, which introduce additional capacitance and enhance shielding performance. Compared with the SICL, the width of the RSICL can be reduced significantly for 50- $\Omega $ characteristic impedance. Hence, the monomode bandwidth of the RSICL is larger than that of the SICL. Closed-form formulas based on the conformal mapping method are derived for fast calculation of the characteristic impedance of the RSICL. Compared with full-wave simulation, the proposed formula has an error of less than 1%. An RSICL with grounded coplanar waveguide (GCPW) transitions is designed and fabricated under print circuit board (PCB) technology. The measurement results show the RSICL with the transitions has a bandwidth from dc to 40 GHz, insertion loss less than 1.9 dB, return loss larger than 10.5 dB, and a data rate of 32 Gb/s with a good eye diagram and low bit error rate (BER). The measured attenuation of the RSICL is 0.021 dB/mm at 40 GHz. Full-wave simulation results show that the width of the RSICL is 6% smaller than that of the SICL, the monomode bandwidth is 6.7% wider, and the energy leakage of the RSICL is only 1/120 of the SICL.

The wetting and joining of SiCf/SiC composites and C/C composites with a high-temperature Si–14Ti (at. %) braze filler were studied for the first time. Wetting dynamics and the contact angle were investigated by heating the Si–Ti sessile droplets on the SiCf/SiC and the C/C substrates. The interfacial micromorphology, shear strength, and fracture characteristics of the joints were all analysed. The Si–Ti alloy had contact angles of ~23° on the C/C and ~7° on the SiCf/SiC at 1460 °C, demonstrating excellent wettability on both substrates. SiC reaction layers were formed at both interfaces of the joint. The reactive infiltration into both substrates occurred during the brazing process, especially in the SiCf/SiC composites. The infiltration structures and the robust bonding were conducive to strengthening the brazed joint. The joint exhibited optimal shear strength values of 31 MPa at room temperature and 40 MPa at a high temperature of 1000 °C.

Rare earth oxides doped hafnia ceramics, with a formula of Hf0.76LnxY0.24-xO1.88 (Ln = Gd, Yb, Gd + Yb or La + Yb), were prepared by solid state sintering at 1500 °C. The effects of the rare earth oxides on the microstructures, sintering resistance, and thermo-physical properties of the doped hafnia ceramics were investigated. Results show that the Gd-Y, Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite (F) structure, while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore (P) and fluorite structures. Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples. The coexistence of P and F phases is beneficial to improved sintering capability. The thermal conductivities of the Gd-Y, Yb-Y and Gd-Yb-Y doped samples are relatively lower (1.4-1.7 W m−1 K−1 at 1200 °C), but for the La-Yb-Y co-doped samples, the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature. The average thermal expansion coefficients (TECs) of the Gd-Y, Yb-Y and Gd-Yb-Y co-doped samples are as high as ∼10.3 × 10−6 K−1 in temperature range between 200−1200 °C.

Additive manufacturing can not only fabricate complicate shaped parts, but also produce new non-equilibrium structures during the rapid heating and cooling process, involving new solid-solution phases and inhomogeous elemental distribution. The 316 L stainless steel (SS) plates were manufactured by laser melting deposition, and the effects of non-equilibrium structures on the corrosion resistance are investigated. The microstructures of the manufactured specimens are analyzed by X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. The corrosion performances are evaluated by electrochemical tests and salt spray tests in NaCl solution. The microstructures of the manufactured 316 L SS specimen are composed of cellular structures, where the boundaries of the cellular structures are enriched with Cr, Mn, Mo, and Nb elements. These cellular structures can significantly enhance the corrosion resistance, representing by higher open circuit potential and small pitting pores compared with the commercial 316 L SS. The reasons of the improved corrosion resistance can be attributed to the high densification and fine cellular structures with the enrichment of Cr and Mo elements at the interfaces.

Environmentally adaptive power generation is attractive for the development of next-generation energy sources. Here we develop a heterogeneous moisture-enabled electric generator (HMEG) based on a bilayer of polyelectrolyte films. Through the spontaneous adsorption of water molecules in air and induced diffusion of oppositely charged ions, one single HMEG unit can produce a high voltage of ~0.95 V at low (25%) relative humidity (RH), and even jump to 1.38 V at 85% RH. A sequentially aligned stacking strategy is created for large-scale integration of HMEG units, to offer a voltage of more than 1,000 V under ambient conditions (25% RH, 25 °C). Using origami assembly, a small section of folded HMEGs renders an output of up to 43 V cm−3. Such integration devices supply sufficient power to illuminate a lamp bulb of 10 W, to drive a dynamic electronic ink screen and to control the gate voltage for a self-powered field effect transistor. A power generator exhibits enhanced output due to a dual-charge-carrier design. The voltage produced is constant yet competitive even under low relative humidity.

A facile method for the quantitative preparation of silver dibenzo-fused corrole Ag-1 is described. In contrast to the saddle conformation resolved by single crystal X-ray analysis for Ag-1 , it adopts an unprecedented domed geometry, with up- and down-orientations, when adsorbed on Ag(111) surface. Sharp Kondo resonances near Fermi level, both at the corrole ligand and the silver center, were observed by cryogenic STM, with relatively high Kondo temperature (172 K), providing the first direct spectroscopic evidence for a non-innocent Ag II -corrole •2- species. Further investigation validates that benzene ring fusion and molecule-substrate interactions play pivotal roles in enhancing Ag (4d x2-y2 )-corrole (π) orbital interactions, thereby stabilizing the open-shell singlet Ag II -corrole •2- on Ag(111) surface. Moreover, this strategy used for constructing metal-free benzene-ring fused corrole ligand gives rise to inspiration of designing novel metal-corrole compound which could be applied to the research of multichannel molecular spintronics devices for data storage and logic gates.

In order to improve the production efficiency of electroslag remelting process and the solidification quality of electroslag ingot, a novel electroslag furnace with electromagnetic stirring was designed and the effects of external magnetic field and different electrical parameters on electroslag remelting process were studied. The distribution of carbon, chromium, phosphorus and compactness in electroslag ingot was analyzed through original position analysis apparatus. Results show that the external magnetic field accelerates the remelting of consumable electrode. Under the condition of remelting voltage of 34 V and current of 1500 A, the remelting rate of metal consumable electrode increases from 20 to 27 mm min−1 when the magnetic induction intensity of 62 × 10−4 and 108 × 10−4 T is applied. However, the remelting current decreases from 1500 to 1100 A under the condition of constant remelting rate and remelting voltage, thereby reducing the energy consumption. The effect of external magnetic field on the segregation of different elements in electroslag ingot is different. Under the experimental conditions, the carbon segregation is unremarkable, but the phosphorus segregation is improved when the electromagnetic force generated by the interaction between the external magnetic field and the remelting current is small. However, the excessive electromagnetic force aggravates the segregation of carbon and phosphorus. With the increase in electromagnetic force, the chromium segregation gradually increases.

A new anhydrous rare-earth metal iodate fluoride, Ce(IO3)2F2, was rationally designed and synthesized. Ce(IO3)2F2 features unique zigzag ∞[CeF2]2+ chains that are bridged by IO3– groups, creating a...

Bulk-fill restorative material has gained popularity in clinical practice, due to their perceived timesaving aspect. Objective was to compare the properties of bulk-fill direct restorative materials. Filtek Z350 (CR), Filtek One Bulk Fill Restorative (BF), Fuji IX and EQUIA Forte (EF) were compared. Thirty specimens from each material were prepared according to ISO 4049 for three-point flexural strength. Elastic moduli and hardness (n = 20) were evaluated using nanoindentation. Depth of cure (DC) (n = 20) was measured for BF at three different depths (2, 3, 4 mm) and at two irradiation times (20 and 40 s). Wear testing was carried out for three different periods (3, 6, 12 month(s)). All specimens were stored in 37 °C water for 24 h prior to testing. Results were evaluated using one-way ANOVA followed by a post hoc Bonferroni test (p &lt, 0.05). BF and CR showed a significantly higher flexural strength than other groups (p &lt, 0.05), and the highest Weibull modulus was found in CR. BF showed sufficient DC with at least 85%, at all thicknesses. CR and BF also had a high level of translucency than EF and Fuji IX. Significant differences in flexural strength were found among all materials except between Fuji IX and EF. While all material tested are suitable for use clinically, BF and CR have superior properties than GIC based bulk-fill.

In this study, aluminum borate whiskers were prepared on the zirconia-toughened alumina (ZTA) substrates for the first time. This result was achieved by calcining a mixture of B2O3 powders with and without adding the MnO2 flux in air. The morphologies of as-prepared whiskers were carefully characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The length-diameter ratio of whiskers prepared by adding MnO2 flux is larger than those prepared by using only B2O3 powders, and the growth mechanisms of whiskers follow solid–liquid–solid theory. In addition, aluminum borate whiskers were successfully used to join ZTA ceramics. By adding the MnO2 flux in the interlayer, the strength of the joints can be significantly improved. The highest flexural strength for the ZTA/whiskers/ZTA joints bonded using B2O3 + 5 wt% MnO2 powders reached 162 ± 11 MPa at 1100 °C after holding for 4 h.

In this paper, Er3+, Yb3+:CeF3 nanoparticles of different sizes were successfully prepared via the hydrothermal method. The effects of Yb3+ ion concentration and the size of nanoparticles on the up-conversion luminescence performance of the materials were investigated through X-ray diffraction, scanning electron microscopy, infrared absorption spectroscopy, and photo luminescence spectroscopy. It was found that these nanoparticles show excellent up-conversion luminescence under a 980 nm laser excitation. The green and red emissions at 517 nm, 543 nm, and 654 nm were, respectively, attributed to the following radiation transitions of the Er3+ ions: 2H11/2 → 2I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2. Furthermore, the emission intensity of the red light was significantly stronger than that of the green light. As the nanoparticles size increased, the luminescence intensity of the samples was significantly reduced. These results demonstrate the great potential of Er3+, Yb3+:CeF3 nanoparticles in bio-imaging, luminescent, anti-counterfeiting, and photocatalysts.

Playing a crucial role in light-emitting diode (LED) illumination sources, the blue light-emitting materials are commonly obtained by doping rare-earth metal ions. Considering the high price, non-r...

In fusion reactors, tritium permeation barrier (TPB) technology is one of the key scientific technologies. α-Al2O3 has been considered an ideal candidate material for TPBs. In this work, a series of first-principles calculations have been performed to investigate the dissolution, clustering and diffusion behavior of hydrogen (H) in bulk α-Al2O3. The calculation results show that the most energetically stable form of hydrogen in a perfect α-Al2O3 crystal under H2 gas annealing treatment is the H2 molecule. This can also be confirmed by the electron localization function results. The attraction between two H atoms located in first and second nearest octahedral interstitial sites (OISs) is so strong that if multiple H atoms are dissolved in α-Al2O3, these atoms can migrate toward their adjacent H atoms and form clusters, which will prevent further diffusion of H. The most stable configuration of H cluster in α-Al2O3 is 2Hi, with the smallest formation energy and the largest average binding energy. The formation energy and binding energy are similar to those of the gaseous H2 molecule. We have derived the temperature-dependent diffusivity of the H2 molecule in α-Al2O3 as D ( T ) = ( 3.65 × 10 − 7 m 2 / s ) e x p ( − 2.27 e V / K T ) , which is in good agreement with the experimental values. In addition, both the dissolution energy and migration barrier of the H2 molecule are so high that dissolution and diffusion of the H2 molecule in α-Al2O3 are very difficult, resulting in low hydrogen permeability.

This study investigates the microstructure evolution and mechanical properties of bare and Co coated AISI 441 ferritic stainless steel/YSZ ceramic reactive air brazed joints achieved by Ag–CuO braze for Solid Oxide Fuel/Electrolysis Cells applications. Interfacial microstructure of steel/YSZ joints is analyzed by SEM and TEM with EDS. A thick and porous oxide layer rich in Fe, Cr, and Cu is found in bare steel/YSZ ceramic joints, which is induced by the severe oxidation and its intense reaction with CuO during the brazing process. For the coated steel/YSZ ceramic joint, a comparably dense and uniform (Co, Fe, Cu)3O4 spinel layer is formed on the steel surface, which is tightly bonded with Ag–CuO braze without visible bonding defects. Meanwhile, the oxidation of steel substrates and its interaction with CuO is significantly suppressed. Co coated steel/YSZ joints possess reliable mechanical properties with the shear strength of 51 MPa, which is 54.5% higher than that of bare steel/YSZ ceramic joints (33 MPa). Besides, the microstructure evolution of coated steel/YSZ ceramic joints during brazing is schematically illustrated by a physical model.

A Si-Zr eutectic alloy was employed as a high-temperature braze filler to join SiCf/SiC composites with Cf/C composites. The interfacial microstructure and bonding mechanism on the side of the SiCf/SiC composites were studied for the first time. The results showed that SiC reaction layers formed between the Si-Zr filler and both substrates. The SiC layer resulted from the chemical reaction between Si and C at the filler–Cf/C interface. In contrast, at the filler–SiCf/SiC interface, coarse-SiC crystals only precipitated on the SiC fibre bundles, and there was only non-reactive bonding between the filler and the SiC matrix. In addition, the reactive infiltration process between the liquid Si alloy and the porous substrates contributed to the formation of infiltration structures, including Cf/C–SiC and SiCf/SiC–Si-ZrSi2, resulting in the reinforcement of the substrates and the joint. Finally, a favourable shear strength of 38 MPa was achieved.

Magnetorheological (MR) fluid is a typical intelligent material which is widely adopted in the mitigation of civil engineering structures, and it is normally composed of nano-sized or micro-sized iron particles, carrier fluids and additives. Because of the complexity of its composition, it is one of the research hotspot to propose a micromechanical model which can effectively describe the micromorphological transformation as well as characteristics of MR fluids. In this study, a single-double chains micromechanical model of MR fluids is proposed by taking into consideration of the influence of volume fraction and magnetic induction on the microstructure evolution of MR fluids based on the coupled field as well as magnetic dipole theory. Additionally, the shear yield stress test of the self-prepared MR fluids with multi-wall carbon nanotubes(MWCNTs) and graphene oxide (GO) composites coated ferromagnetic particles is carried out by MCR302 rotational rheometer and the results have been compared with the theoretical values of the single-double chains micromechanical model to verify the effectiveness and accuracy of the proposed model.

Hundreds of copper and titanium foils were applied to prepare biomimetic metal-intermetallic laminated composites by diffusion bonding. The cross sections of the obtained diffusion bonded bulks were etched selectively with FeCl3 solution to get regular microarray structures. This kind of microstructure was controlled accurately and promptly by simple parameter adjustment. The etched surfaces were modified with 1-dodecanethiol, and the water contact angles (WCAs) were measured. The relationship between the microstructure and wettability of the achieved material was discussed, and the reason for the anisotropic wettability was also analyzed. Then etched surfaces were anodized in different electrolyte solutions to obtain different nanostructures. The morphology and chemical compositions of the surfaces were analyzed. The surfaces with CuO nanostructures by modification show superhydrophobicity with self-cleaning, on which the WCA and water sliding angle are 160.9° and 0.8°, respectively. The surfaces with TiO2 nanostructures without modification show ultraviolet light-responsive wettability. After modification with 11-mercaptoundecanoic acid and 1-decanethiol, the surfaces also exhibit pH-responsive wettability. The superhydrophobic surfaces with responsive wettability have potential applications in biotechnology and microfluidics.

This study experimentally investigated the heat transfer characteristics of the heat sink situated in a rectangular channel with the axial main flow under a transverse synthetic jet. The heat sinks, made of aluminum alloy, were divided into three kinds: the finned heat sinks, the in-line pin-fin heat sinks and the pure aluminum-foam heat sink. Total 7 heat sinks were used as test specimens. There was a fixed bypass space between the heat sink and the upper cover of the channel. The synthetic-jet device was separately placed above the leading edge of heat sink, normally above the heat sink and above the trailing edge of heat sink. Under current test parameters, the heat transfer capability of the system with the synthetic jet was around four times that without the synthetic jet. When the value of Rej/Re was bigger than 2.4, the synthetic jet would enhance the heat transfer of the present cooling system above 50%. The cases with the smaller diameter of synthetic-jet nozzle had the better heat transfer enhancement. The Nusselt number of the pure aluminum-foam heat sink was the lowest, and its heat transfer was lower than that of the highest group by 30 ~ 40%.

The interfacial reactions between lead-free solders Sn, Sn-3.0 wt.% Ag-0.5 wt.% Cu (SAC) and Sn-9 wt.% Zn (SZ), and Cu-2.0 wt.% Be (Alloy 25) were investigated using the liquid/solid couple technique. The couples were reacted at 240–270°C for 0.5–10 h. The results revealed that only the scallop-shaped (Cu, Be)6Sn5 phase was formed at 240°C for 0.5–2 h in the Sn/Alloy 25 couple. At a longer time (> 4 h) or higher temperature (255°C and 270°C), the (Cu, Be)3Sn phase was observed at the interface. In the SAC/Alloy 25 couple, the results were similar to that in the Sn/Alloy 25 couples. Only the scallop-shaped (Cu, Be, Ag)6Sn5 phase was formed for the short reaction time or at lower reaction temperature. With increasing reaction times and temperatures, both the (Cu, Be, Ag)6Sn5 and (Cu, Be, Ag)3Sn phases were observed at the SAC/Alloy 25 interface. In the SZ/Alloy 25 couple, the (Cu, Sn)Zn5 and (Cu, Sn)5Zn8 phases were observed. Of these three couples, the intermetallic compound (IMC) thickness obeyed the parabolic law, and the IMC growth mechanism was diffusion-controlled.

Photodetectors based on two-dimensional/three-dimensional (2D/3D) semiconducting heterostructures have attracted tremendous attention in recent years due to their novel performance. Here, we found that the photodetection performance of the graphene (Gr)/Si 2D/3D heterostructure can be very broadly enhanced by introducing an optimized ultrathin WS2 film prepared by sulfidation as an interfacial layer. The fabricated Gr/WS2(10.9 nm)/Si photodetector shows a wide spectralresponse from 400 to 1800 nm with a maximum photoresponsivity of 8.96 × 104 A W−1 and photodetectivity of 8.86 × 1011 Jones at 690 nm, which are more than three orders of magnitude higher than that of the Gr/Si photodetector. Such a high photoresponsivity can be attributed to the strong photogain induced by the hole trap states that exist in the WS2 film. With the increase in the WS2 film thickness, the photoresponsivity increases firstly owing to the increase of hole trap states, and then decreases due to the decrease in light transmittance through WS2. The device also shows a high responsivity of 0.735 A W−1 at 1550 nm by forming type-II interlayer excitation. Our results indicate that 2D transition metal dichalcogenides (TMDCs) could be a good candidate functioning as an interfacial layer for high performance Gr/Si photodetectors, which provide a facile way for enhancing the photodetection performance of van der Waals 2D/3D heterostructure photodetectors.

Cyanurate motifs are emerging functional basic blocks (FBBs) for nonlinear optical (NLO) materials and birefringent materials. Herein, we report two new potassium lead(II) hydroisocyanurates, namely, K2Pb(H2C3N3O3)4(H2O)4 (I) and K3Pb(H2C3N3O3)5(H2O)6 (II). I and II belong to acentric Cm and centric C2/m, respectively. Compound I features a novel 3D network formed by 2D [K2PbO8(H2O)4]12− anionic layers interconnected by (H2C3N3O3)− anions. The 2D [K2PbO8(H2O)4]12− anionic layer is composed of 1D chains of edge-sharing K(1)O6 and K(2)O8 being further interconnected by 8-coordinated Pb2+ ions. Compound II exhibits a characteristic 3D framework based on 2D [K3PbO11(H2O)6]17− anionic layers interlinked through (H2C3N3O3)− groups, and the 2D [K3PbO11(H2O)6]17− anionic layer is based on K–O/H2O chains bridged by Pb2+ ions. Powder second harmonic generation (SHG) measurements of I revealed a moderate SHG response of approximately 2.6 × KDP with a type I phase-matching behavior under 1064 nm laser radiation. Theoretical calculations of I and II revealed their birefringence to be 0.325 and 0.193@532 nm, respectively. Their impressive optical properties mainly stem from stereochemically active lone pair (SCALP) Pb2+ cations and the planar π-conjugated (H2C3N3O3)− groups.

A high optoelectronic performance ReS2/ReSe2 van der Waals (vdW) heterojunction phototransistor utilizing thin hafnium oxide (HfO2) as a local-back-gate dielectric layer was prepared and studied. The heterojunction-based phototransistor exhibits a superior electrical performance with a large rectification ratio of ∼103. Furthermore, unlike diode-like heterojunction devices, the innovative introduction of a local-back-gate in this phototransistor provides an outstanding gate-tunable capability with an ultra-low off-state current of 433 fA and a high on/off current ratio of over 106. And under optical excitation of a wide spectrum from 400 to 633 nm, an excellent photodetection responsivity at the 104 A W−1 level and the maximum normalized detectivity of 1.8 × 1015 Jones @ 633 nm have been demonstrated. Such high performances are attributed to the band alignment of the type-II heterojunction and the suppression of dark current by the local-back-gate. This work provides a promising reference for two-dimensional (2D) Re-based heterojunction optoelectronic devices.