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A Ni60/Ni-WC composite coating was fabricated by the plasma spraying technology and microstructure of the coating was analyzed. Moreover, erosion resistance of the coating under different erosion angles was tested. Results demonstrated that the coating has lamellar structures and contain some pores. WC particles distribute evenly in the coating and bond well with the parent phase. When the erosion angle increase, the weight loss of the erosion-induced coating increases firstly and then decreases, showing plastic-brittle composite erosion characteristics.

Water clustering structures are considered to play key roles in various temperature-dependent life activities. However, our fundamental understanding of the temperature-dependent water structures remains murky because of the limits of the real-time and real-condition monitoring techniques at the molecular level. We propose an in situ ATR-IR approach combining Gaussian fitting to qualitatively and quantitatively explore the temperature-dependent structural stability and transformation of the three water components, multimer water (MW), intermediate water (IW), and network water (NW), on interfaces with different wettabilities. Our results show that the transformation between NW and IW/MW will occur with a change in temperature. This conversion process shows reversibility on hydrophilic Au NPs film/ZnSe, while it is irreversible on a hydrophobic mercaptohexane self-assembled monolayer due to the irreversibility of the monolayer structure and the hydrophobic confinement effect. The established approach enables us to explore the change in the water properties at any interfaces upon external stimuli.

In order to investigate the dynamic characteristics of blunt aircraft mounted with aerospikes and aerodisks in large-amplitude force-pitching, the Roe spatial scheme and the lower-upper symmetric Gauss-Seidel (LU-SGS) method with dual time step are employed for discretization of unsteady Navier-Stokes (N-S) equations. A parametric investigation on the flow fields is conducted by altering the pitching period, aerospike length, and aerodisk diameter consequently via a variable-controlling procedure. Dynamic characteristics of aerodynamic drag as well as the visualization of unsteady flow fields are achieved, and the results show that the aerodynamics of hypersonic aircraft under the condition of large-amplitude force-pitching vibration have hysteresis characteristics affected by periods of force-pitching vibration. In addition, when changing aerospike length and aerodisk diameter, the variation tendency of drag reduction efficiency is determined by the pitching angle of the oscillation process.

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Biological ion pumps with two separate gates can actively transport ions against the concentration gradient. Developing an artificial nanofluidic device with multiple responsive sites is of great importance to improve its controllability over ion transport to further explore its logic function and mimic the biological process. Here, we propose an electrochemical polymerization method to fabricate electrochemically switchable double-gate nanofluidic devices. The ion transport of the double-gate nanofluidic device can be in situ and reversibly switched among four different states. The logic function of this nanofluidic device is systematically investigated by assuming the gate state as the input and the transmembrane ionic conductance as the output. A biomimetic electrochemical ion pump is then established by alternately applying two different specific logic combinations, realizing an active ion transport under a concentration gradient. This work would inspire further studies to construct complex logical networks and explore bioinspired ion pump systems.

The change of bubbles and the position of the tuyere in an oxygen coal combustion melting and separating furnace affect the flow and splash behavior of the molten pool. To analyze this problem further, a three-dimensional numerical simulation method was used to explore the behavior and change of the flow field inside the molten pool during double-row tuyere injection. In addition, the arrangement of the tuyere was changed for a more detailed understanding of the internal phase distribution and splashing in a molten pool. The results indicated that under three-dimensional numerical simulation conditions, bubbles rise after leaving the tuyere and break on the surface of the molten pool, which results in certain fluctuations in the nearby melt. During the injection process of the tuyere, the meteorological accumulation in the middle part of the molten pool formed part of the foam slag because of the influence of surface tension. When the layout of the upper and lower exhaust tuyeres was changed from staggered to symmetrical, or when the spacing of the upper and lower exhaust tuyeres changed, it had an effect on the phase distribution and splash behavior.

Miniaturized and manipulable optical probes are the foundation for developing in situ characterization devices in confined space. We developed two methods for fabricating free-standing single Ag nanowires (AgNWs) directly at the tip of a glass capillary either by chemical or electrochemical reduction. The electrochemical nature of both methods resulted in a rapid growth rate of AgNWs up to 1.38 μm/s and a controllable length from 5 to 450 μm. The AgNWs with a unique anisotropic structure allow localized surface plasmon resonance and surface plasmon waveguides in the radial direction and axial direction, respectively. We verified the possibility of using single AgNWs as an optical dispersion device and waveguide probe. By controlling the experimental conditions, rough-surface AgNWs with high surface-enhanced Raman scattering (SERS) activity were also fabricated. These SERS-active probes also exhibited advantages in acquiring molecular information from a single living cell.

oriented PbTiO3 nanoplates with an average aspect ratio of approximately 5 were synthesized by a one-step hydrothermal method. The factors that could affect the growth of the PbTiO3 nanoplates, such as the concentration of the mineralizer (KOH) and ratio of Pb2+/Ti4+ in the source materials, were carefully investigated. A modified growth process of the PbTiO3 nanoplates was proposed by a time variation evaluation. Therefore, the typical growth parameters were set to 200 °C/10 h, Pb2+/Ti4+ = 1.25 (Mp25 = 5 mmol and MPb(NO3)2 = 6.25 mmol), and MKOH = 8 mol/L (in 30 ml of DI water) with P25-TiO2 and Pb(NO3)2 as the source materials. Furthermore, the d33 versus applied voltage curve showed good ferroelectric behavior with a maximum d33 value of ~ 165 pm/V, indicating promising potential as seeds for templated grain growth (TGG) of PbTiO3 nanoplates.

Although metal nanoclusters (MNCs) have shown great promise for the further development of photochemical techniques to be applied in diverse areas (e.g., photoelectronic devices, photochemical sensors, photocatalysts, and energy storage and conversion systems), the fundamental problem of their electron transfer behavior still remains unsolved. Herein, a driving force-dependent photoinduced electron transfer process of gold nanoclusters (AuNCs) is clarified for the first time from a rational-designed opposite-charged system. It was found that the electron transfer dynamic of carboxylated chitosan and dithiothreitol-commodified AuNCs (CC/DTT-AuNCs) can be satisfactorily described by the Marcus electron transfer theory. This proved model was applied to estimate the ultrafast charge separation process between CC/DTT-AuNCs and mitoxantrone, which was confirmed by fluorescence quenching and femtosecond transient absorption spectroscopy measurements. We envision that this work will open a new door for understanding the electron transfer behavior of MNCs and facilitate the design of advanced optoelectronic devices.

Mg3B2O6 is a typical microwave dielectric ceramic with a high Qf value, but the pure Mg3B2O6 ceramic is difficult to be obtained due to the volatilization of B2O3 resulting from the high temperature during the fabrication process. We reveal the effects of Mg/B ratio and Sr2+ substitution for Mg2+ on the phase composition, sintering behavior, microstructure, and microwave dielectric properties of Mg3B2O6. The pure Mg3B2O6 ceramic can be obtained with Mg/B ratio equal to 1.2. Proper excessive free-MgO is benefit to the improvement of Qf value of Mg3B2O6, while it is detrimental to the densification of Mg3B2O6. No second phase was detected in the Sr2+ substituted Mg3B2O6 and excellent microwave dielectric properties (er = 6.9, Qf = 110820 GHz, and τf = -32.4 ppm/°C at 12.8 GHz) were obtained in the (Mg0.998Sr0.002)3B2O6 (x = 0.2 mol.%) ceramic sample sintered at 1250 °C for 3h, making it a hopeful candidate for wireless communications. These results bring forward the underlying insights needed to direct the design of microwave dielectric ceramics with high Qf values for personal communication applications.

An experimental programme and nonlinear finite element analysis are carried out to examine the ultimate strength characteristics of stiffened panels with a crack and pits, under uni-axial longitudi...

CuO-added 0.96(Na0.5K0.5)(Nb1-x Sbx)-0.04BaTiO3 ceramics with 0.0 ≤ x ≤ 0.1 were sintered at 980°C for 6 hours and the effects of antimony on the successive phase transition and the corresponding piezoelectric properties were carefully studied. It was found that with the increasing of x values, the crystal structures varied from orthorhombic-tetragonal polymorphic phase boundary (PPB), orthorhombic-tetragonal-cubic PPB, and finally to the tetragonal-cubic PPB structure. Accordingly, the piezoelectric properties of the specimens were influenced by the varied crystal structures. In particular, the specimen with a tetragonal (88.01%)-cubic (11.99%) PPB structure (x = 0.06) showed a large d 33 of 302 pC/N and a high strain of 0.17% at 4.5kV/mm, revealing its promising potential as the Pb-free piezoelectric actuators.

As an important damping way of the light absorption of plasmonic nanoparticles, the d-sp interband transition within the short wavelength regime has been recently drawing attentions in photochemistry. Compared with the intraband Landau damping, the d-sp interband transition excited carriers have larger populations and longer relaxation times, which is promising to match the photochemical reactions in time scale. Here, we propose a novel approach to the growth of plasmonic gold nanoparticles more efficiently promoted by d-sp interband transition excited charge carriers than by plasmon excited carriers. It is founded that photochemical growth of plasmonic gold nanoparticles can be modulated by engineering the electrochemical potential of precursor using different surfactants. From the distribution of surfactant on a single gold nanoparticle revealed by nanoscale resolved IR mapping, a reasonable photochemical reaction mechanism mediated by d-sp interband excitation is suggested. The results highlight the importance of d-sp interband transition excited carriers in photochemical reactions especially for materials science.

A low-cost (Mg1-xCax)3B2O6 (0 ≤ x ≤ 1.0 mol.%) (MCxB) microwave dielectric ceramic was prepared by solid-state method. X-ray diffraction, scanning electron microscope, and vector network analyzer were adopted to characterize the phase composition, microstructure, and microwave dielectric properties of the as-fabricated MCxB ceramics. All the MCxB (x = 0–1.0 mol.%) ceramic samples exhibit the singe orthorhombic structure corresponding to Mg3B2O6 (JCPDS 75–1807). Excellent microwave dielectric properties (er = 6.8, Q × f = 103,556 GHz, τf = − 34.5 ppm/°C at 12.6 GHz) were obtained in the MC0.002B (x = 0.2 mol.%) ceramic sintered at 1250 °C for 3 h, making it a prospective candidate for the practical application in portable terminal and wireless communications.

We report a new mass spectrometric method for detecting electrogenerated intermediates. This approach is based on simultaneous activation of electrospray ionization and redox reaction on a wireless bipolar ultramicroelectrode, which is fabricated in the tip of a quartz nanopipette. The hollow structure of the ultramicroelectrode permits rapid transferring the transient species from electrode-electrolyte interfaces into the gas phase for mass spectrometric identification on the time scale of microseconds. The long-sought fleeting intermediates including TPrA.+ , whose lifetime in solution is only 200 μs, and catecholamine o-semiquinone radicals, the second-order rate constant of which is typically 109 m-1 s-1 , were successfully identified, helping clarify the previously hidden reaction pathways. Accordingly, our method may have wide applicability in exploring the dynamics of many electrochemical reactions, especially their ultrafast initial steps.

Rational construction of low-cost, efficient, and durable electrocatalysts for the hydrogen evolution reaction(HER) is essential to further develop water electrolysis industry. Inspired by the natural enzyme catalysis with coordination environments of catalytic sites and three-dimensional structures, we construct an efficient Ru-based catalyst anchored on the nitrogen dopant on graphene aerogel(Ru-NGA). The Ru-NGA catalyst exhibits dramatically improved electroactivity and stability towards HER with a near-zero onset overpotential, a low Tafel slope of 32 mV/dec, and a high turnover frequency of 5.5 s−1 at −100 mV. The results show that the electronic modulation of metallic Ru nanoparticles by nitrogen coordination weakens the affinity of Ru towards H and hence facilitates the desorption of hydrogen. This research provides in-depth insights into the fundamental relationship between metallic nanostructure and HER activity, and also guides the rational design of high-performance electrocatalysts in energy conversion.

Electrochemical conversion of CO2 into fuels is a promising means to solve greenhouse effect and recycle chemical energy. However, the CO2 reduction reaction (CO2RR) is limited by the high overpotential, slow kinetics and the accompanied side reaction of hydrogen evolution reaction. Au nanocatalysts exhibit high activity and selectivity toward the reduction of CO2 into CO. Here, we explore the Faradaic efficiency (FE) of CO2RR catalyzed by 50 nm gold colloid and trisoctahedron. It is found that the maximum FE for CO formation on Au trisoctahedron reaches 88.80% at −0.6 V, which is 1.5 times as high as that on Au colloids (59.04% at −0.7 V). The particle-size effect of Au trisoctahedron has also been investigated, showing that the FE for CO decreases almost linearly to 62.13% when the particle diameter increases to 100 nm. The X-ray diffraction characterizations together with the computational hydrogen electrode (CHE) analyses reveal that the (2 2 1) facets on Au trisoctahedron are more feasible than the (1 1 1) facets on Au colloids in stabilizing the critical intermediate COOH*, which are responsible for the higher FE and lower overpotential observed on Au trisoctahedron.

Electrochemical conversion of N2 to NH3 under ambient conditions is a promising and environmentally friendly route compared with the CO2-emitting and energy-intensive Haber-Bosch process. Nevertheless, due to ultrahigh stability of N2, it is urgent to explore efficient catalysts to weaken and activate the N≡N bond. Here, we report the Mo-doped iron phosphide (Mo-FeP) nanosphere as a valid transition-metal-based catalyst for electrochemical N2-to-NH3 fixation under ambient conditions. This catalyst exhibits excellent catalytic performance with a NH4+ yield rate (13.1 μg h-1 mg-1) and Faradaic efficiency (7.49%) at -0.3 and -0.2 V vs reversible hydrogen electrode (RHE), respectively. However, the FeP catalyst without doped Mo species displays weak catalytic performance. We found that the better catalytic performance of Mo-FeP might be due to the doping of Mo species, which is favorable for the polarization of adsorbed N2 molecules, making the N≡N bond more viable to dissociate.

Protein-supported nanoparticles have a great significance in scientific and nanotechnology research because of their “green” process, low cost-in-use, good biocompatibility, and some interesting pr...

Dynamic modulus of elasticity and damping ratio are two important parameters of dynamic properties of soil. These two parameters were extensively studied in the laboratory. However, there has been little research on these two parameters of the unsaturated red clay which is located in the southwest of Hunan, China. With the rapid development of high-speed railway in China, it is urgent to identify the dynamic properties of the unsaturated red clay to provide reference for the civil engineering industry. In this paper, DDS-70, an electromagnetic type dynamic tri-axial testing system, was used to study the effects of water content, dry density, confining pressure, over-consolidation ratio and loading frequency on dynamic elastic modulus and damping ratio of unsaturated red clay. The result shows that within the phase of small strain the influences of water content, dry density, confining pressure, over-consolidation ratio and loading frequency on dynamic modulus of elasticity are obvious. Dynamic modulus of elasticity increases with the increase of dry density, confining pressure and over-consolidation ratio under the same strain, whereas dynamic modulus of elasticity decreases with the increase of water content and loading frequency. Moreover, the effects of these factors on damping ratio are also significant during the phase of small strain. With the increase of strain, damping ratio increases with the decrease of dry density, confining pressure and over-consolidation ratio under the same dynamic strain. There is no clear relationship between damping ratio and loading frequency. It is concluded that the influence of above factors on the dynamic modulus of elasticity and damping ratio is significant.

The sintering behaviors and dielectric properties of the Li2MgTiO4 ceramics at microwave frequency were investigated as a function of BaCu(B2O5) in this paper. The addition of BaCu(B2O5) dramatically decreased the sintering temperature of Li2MgTiO4 ceramics from 1250 to 900 °C. No secondary phase was detected and single phase Li2MgTiO4 with NaCl structure in the 1.0–4.0 wt% BaCu(B2O5) doped Li2MgTiO4 ceramics was confirmed, while a small amount of BaCu(B2O5) phase was found in the 8.0 wt% BaCu(B2O5) doped Li2MgTiO4 ceramics. No much deterioration of dielectric properties at microwave frequency of the BaCu(B2O5) doped Li2MgTiO4 ceramics sintered at 900 °C for 3 h occurs and favorable dielectric properties (er = 15.8, Qf = 74,790 GHz and τf = − 24.3 ppm/°C) at microwave frequency were obtained for the Li2MgTiO4 ceramics with 4.0 wt% BaCu(B2O5) addition. Accordingly, such a favorable 4.0 wt% BaCu(B2O5)-doped Li2MgTiO4 ceramic might be a potential candidate material for LTCC applications.

Plasmonic metal/semiconductor nanohybrids hold great promise in photocatalysis and biosensor development; however, their potential phototherapeutic applications are yet fully unexplored. On the other hand, the demand of high laser power density to induce antibacterial photothermal therapeutic effects greatly restricts the practical applicability of the previously developed photothermal nanoagents (PTAs) for anticancer photothermal therapy (PTT). Here, we develop a plasmonic nanohybrid by integrating plasmonic noble metal gold nanorods (AuNRs) with a two-dimensional graphene oxide (2-D GO), capable to perform photothermal ablation of both bacterial pathogens as well as tumor cells, respectively, under low power single near-infrared (NIR) laser activation. Owing to the synergistic plasmonic photothermal effect (PPTT) of dual plasmonic PTAs, the plasmonic AuNR/GO nanohybrid exhibits remarkably higher photothermal conversion efficiency (PCE, 72.59%) than either individual AuNRs or GO under low laser power density (300 mW), leading to enhanced antibacterial/anticancer PTT. In addition, the synergistic plasmonic antibacterial/anticancer PTT induced by the plasmonic nanohybrid is also far superior to individual PTAs (AuNRs or GO), whereas the flow cytometric analysis of heat shock proteins (HSP 70) clearly dictates that the substantial killing of bacterial pathogens/tumor cells is solely due to the synergistic PPTT. Thus, the plasmonic AuNR/GO nanohybrid is a standalone PTA to perform simultaneous antibacterial/anticancer PTT under low power NIR laser activation for only 5 min, without any systemic side effects. The present study provides a clear demonstration about the potential therapeutic impact of plasmonic nanohybrids and thus will surely pave the way to design other hybrid nanoagents with enhanced PCE and integrate them with chemotherapeutic agents, leading to dual-modal chemo-/photothermal antibacterial/anticancer therapy under low power single laser excitation for a short duration.

Few-atom gold nanoclusters (AuNCs) have been fabricated and used for various fields owing to their remarkable optical and photophysical features. However, the rational design for the antibody-mediated synthesis of fluorescent AuNCs for direct antigen-antibody reactions remains unexplored. In this work, immunoglobulin G (IgG)-functionalized AuNCs (IgG-AuNCs) were successfully prepared via a facile and fast biomineralization process. The generated IgG-AuNCs can emit intense red fluorescence with a high photoluminescence quantum yield. Besides strong emission, the bioactivity of IgG on the IgG-AuNCs can be retained. Surface plasmon resonance measurements suggested that IgG-AuNCs can bind to goat anti-human IgG with an affinity constant of 6.21 × 10-8 M. A simple detection method was then developed using a dot-blot immunoassay with IgG-AuNCs as fluorescent tags. Experimental results confirmed that the IgG-AuNC-based fluorescent reporters had many advantages such as low nonspecific adsorption and good photostability, offering immense potential for the development of efficient biosensors. This work can be extended to other specific antibodies to produce multifunctional AuNCs and utilized to detect and monitor targeted analytes and biological events of interest.

This report outlines a versatile high-performance electrochemiluminescence (ECL) enzyme-linked immunosorbent assay (ELISA) platform, which combines the merits of high-quantum-yield Au nanocluster (AuNC) probe-based ECL technology, the efficient ECL-resonance energy-transfer (ECL-RET) strategy, and highly sensitive and specific ELISA technology. The ECL detection procedure was performed on a recyclable MnO2/AuNC-modified glassy carbon electrode interface by taking advantage of the ECL-RET between the AuNC probe and MnO2 nanomaterials (NMs) to quench the ECL intensity. The etching of MnO2 NMs by the product of ALP-based ELISA recovers the ECL signal. Notably, the ELISA process and the ECL detection procedure in this system are independent. Thus, the ECL-ELISA system can effectively avoid the influence of complex biological samples, and the ECL efficiency of the AuNC probe can be used readily. As demonstrated on TNF-α, because of the abovementioned characteristics, the ECL-ELISA platform presented an extremely wide dynamic range, with a detection limit of 2 orders lower than ELISA. Moreover, the system was also applicable for ultrahigh sensitive detection of various disease-related proteins and able to detect trace biomarkers in real serum samples. Therefore, this multifunctional ECL assay platform is versatile, facile, ultrasensitive, recyclable, and sufficiently straightforward for trace biomarker detection in complex biological samples. This approach not only enriches the foundational study of ECL devices but also greatly expands the potential application of ECL sensors in biological testing and clinical high-throughput diagnosis.

Emulsion explosives (EE) are one of a typical industrial explosive that is widely used in engineering and mining applications due to its high detonation performance and ideal safety characteristics. However, since an EE is a multicomponent mixture with an oil-in-water structure, the presence of some substances or impurities can reduce the safety of the EE and cause accidents. We investigated the influence of ferrous ion on the thermal behavior and stability of EE during production and storage. The thermogravimetry–differential scanning calorimetry and water solubility method were selected for the assessment of thermal behavior and stability of the EE. According to kinetic parameters, the apparent activation energy (Ea) of the EE and the EE with ferrous ion additives was determined. The results indicated that ferrous ion could decrease the thermal decomposition temperature and Ea of EE. Moreover, the degree of crystallization of ammonium nitrate increases as storage time and ferrous ion content increases. It is of important significance to reduce the hazards of the EE and to improve both safety and stability during production and storage.

This paper presents a numerical investigation on concrete-filled steel tubular (CFST) beam-columns with square sections subjected to combined sustained load and corrosion. A general numerical method is used for the simulation of the time dependent behaviour of the core concrete, while the wall-thickness loss of the outer steel tube induced by corrosion is considered in this model simultaneously. The established finite element analysis (FEA) modelling is verified with test data and used for further investigations of the load-deformation relationship, load-transfer mechanism, stress and strain development, failure modes and ultimate states on CFST beam-columns when suffering combined sustained load and corrosion. Parametric studies are conducted to reveal the effects of key parameters, based on which simplified design method is suggested for square CFST beam-columns under combined sustained load and corrosion.

Electronic modulation of heterogeneous metal catalysts has been considered as an effective means to optimize their catalytic performance. Two-dimensional nanomaterials, typically used as the supporting substrates for anchoring the active metal nanoparticles, are well-known to profoundly influence the electronic structure of metals through interfacial electronic metal–support interaction (EMSI). However, the detailed investigation of EMSI for catalytic enhancement still remains obscure at the microscopic level. Herein, we propose to utilize MoS2 nanosheets to modulate the electronic structure of Pd through EMSI and investigate the influence of “support effect” of MoS2 on the catalytic activity of Pd utilizing degradation of methylene blue (MB) with the electron donor NaBH4 as a simple model reaction. Mechanistic investigations reveal that the electron transfer from Pd to MoS2 makes a highly electron-deficient Pd surface. During the target catalysis, this interfacial electronic structure makes the surface o...

Ion transport in bionanopores is closely related to biological processes and can be regulated by various external stimulations. Multivalent ion as one of the stimulators shows a great ability in tu...

We report a high-performance Ru@C4N electrocatalyst for the hydrogen evolution reaction (HER) in both acidic and alkaline solutions. This catalyst is synthesized by annealing a complex of a covalen...

Micro-/nanofluidics has received considerable attention over the past two decades, which allows efficient biomolecule trapping and preconcentration due to ion concentration polarization (ICP) within nanostructures. The rich scientific content related to ICP has been widely exploited in different applications including protein concentration, biomolecules sensing and detection, cell analysis, and water purification. Compared to pure microfluidic devices, micro-/nanofluidic devices show a highly efficient sample enrichment capacity and nonlinear electrokinetic flow feature. These two unique characterizations make the micro-/nanofluidic systems promising in high-performance bioanalysis. This review provides a comprehensive description of the ICP phenomenon and its applications in bioanalysis. Perspectives are also provided for future developments and directions of this research field.

BaCu(B2O5) is a typical microwave dielectric ceramic (MDC) with a low sintering temperature, but it exhibits a large negative temperature coefficient of resonant-frequency (τf) which makes it difficult to use in wireless communications. We employ TiO2 to improve its temperature-stability of resonant-frequency, and reveal the effects of TiO2 on the densification and the microwave dielectric properties of BaCu(B2O5). Here we show that BaCu(B2O5) can be well-sintered at 825 °C with proper TiO2 additions; we find that the TiO2 grains homogeneously distribute in the boundaries of BaCu(B2O5) grains, resulting in the τf compensation of BaCu(B2O5). Enhanced temperature-stability of resonant-frequency can be achieved by increasing the content of TiO2 properly. A novel temperature-stable (1-x)BaCu(B2O5)–xTiO2 (x = 0.20) MDC (τf =−0.8 ± 3.0 ppm/°C, er = 8.8 ± 0.36, Q×f = 28,612 ± 1170 GHz) is obtained using some low-cost raw materials. Our results provide the underlying insights needed to guide the design of temperature-stable MDCs for wireless communication applications.

This paper presents an experimental study on concrete-filled steel tubular (CFST) beam-columns with square sections under combined sustained load and chloride corrosion. A total of 11 specimens (including 7 CFST members and 4 reference hollow steel tubes designed for comparison) were tested under 120-day sustained load in accelerated chloride corrosion environment and then loaded to failure. The main test parameters include load ratio (ratio between the long-term sustained load and the ultimate capacity of the specimen under short-term loading) and corrosion depth. The failure modes, full-range load-displacement relationship, load-strain relationship and ductility were measured and compared. Based on the experimental observation, mechanism of CFST beam-column members under the combined effects of sustained load and chloride corrosion was discussed and compared to the reference hollow steel tubes. Traditional design methods were modified for the consideration of combined sustained load and corrosion, which were calibrated and evaluated against the test results.

First-principles calculations are used to investigate the electronic and magnetic properties of substitutional doping of transition metal (TM) atoms (V, Cr, Mn, Co, Ni, Cu and Zn) on marcasite FeS2 (m-FeS2). It is energetically favorable to combine TM atoms into m-FeS2 under S-rich condition. The electronic properties of m-FeS2 are changed significantly due to the introduced impurity states by TM atoms. Simultaneously, TM atoms doping can induce magnetism in m-FeS2 except Cu and Zn. The magnetism stem from the localized unpaired 3d electrons of TM atoms, a small amount of magnetic moments are induced in the neighboring Fe and S atoms due to the p–d hybridization mechanism. V-, Mn- and Ni-doped m-FeS2 compounds exhibit magnetic semiconducting character, Cr-doped compound display a half-metallic property, while Cu-doped compound shows non-magnetic metallic property, Zn-doped compound behavior as a non-magnetic semiconductor. More interestingly, a single Co-doped compound shows magnetic semiconducting but double Co-doped compound shows half metallic character. In addition, Co- and Cr-doped compounds prefer ferromagnetic state which is important for spintronics.

Three PbTiO3 nanostructures were synthesized using a one-step hydrothermal reaction with different TiO2 powders as Ti sources, and their gas-sensing properties were investigated. The sensor comprising PbTiO3 nanoplates (NPs) exhibited a high response (resistance ratio = 80.4) to 5 ppm ethanol at 300 °C and could detect trace concentrations of ethanol down to 100 ppb. Moreover, the sensor showed high ethanol selectivity and nearly the same sensing characteristics despite the wide range of humidity variation from 20 to 80% RH. The mechanism for humidity-independent gas sensing was elucidated using diffuse reflectance infrared Fourier transform spectra. PbTiO3 NPs are new and promising sensing materials that can be used for detecting ethanol in a highly sensitive and selective manner with negligible interference from ambient humidity.

Attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a powerful technique that provides structural and functional information during dynamic reactions in aqueous solutions. One existing limitation is the sensitivity to extract the signals of trace-level analytes from the background water in situ and in real time. Here, we proposed a novel ATR-SEIRAS platform that integrated a large-scale triangle gold antenna array onto a conventional ATR-IR platform to increase the sensitivity of this analytical technique. A square centimeter level well-ordered gold antenna array was fabricated onto an Si prism via nanosphere lithography. The size-dependent antenna array resonance had weak correlation with the incident polarization and antenna orientation, allowing antenna array-enhanced IR detection without the requirement of a microscope. In addition, the antenna resonance shift that occurred due to analyte adsorption-induced refractive index variation could be minimized benefiting from the high refractive index of Si (3.4). As a demonstration, we dynamically monitored the adsorption of the trace levels of proteins on top of the antenna array with a real signal enhancement factor larger than 300. Our platform opens an avenue to apply antenna array-enhanced IR spectroscopy in an aqueous environment measured via commercial IR instruments, which is extremely promising for the interfacial applications that require signal enhancement.

Water splitting for the oxygen evolution reaction (OER) through electrocatalysis holds significant promise for energy conversion. However, its real application is yet hindered owing to the lack of efficient electrocatalysts. Herein, we propose a plasmon activation approach for the acceleration of the OER on a Au nanorod–2D ultrathin metal–organic framework (NiCo-MOF) hybrid. The plasmon-generated hot holes of Au nanorods (AuNRs) can be injected into the nickel active sites of the OER catalyst, significantly increasing the generation of high valence Ni* active species in NiCo-MOFs with better matched energy levels for the OER, in turn decreasing the OER activation energy. Thus, excellent OER performance of the NiCo-MOFs under surface plasmon resonance of AuNRs is achieved with an overpotential of 240 mV at a current density of 10 mA cm−2 and a Tafel slope of 69 mV dec−1, which is much better than that of the reported catalysts. This finding highlights the importance of noble metal LSPR in facilitating the OER performance of MOFs and opens up a new avenue for improving the intrinsic electrocatalytic activity of pristine MOFs.

The residual ultimate strength of steel stiffened plates damaged with a crack and subjected to axial compression is determined by using the nonlinear finite element method. The numerical method is verified by comparing the finite element results with experiments made to investigate the influence of varying orientation, length and location of the crack. Under the gradual compression loading, the stress intensity factor is given to check the crack propagation before the structure collapses. The initial weld induced plate distortions have a significant effect on the residual ultimate strength including the measured data by tests and the buckling-type one. A series of analysis is performed to study the effect of the different boundary conditions of the longitudinal edge, different type of initial deformations and the different cracks.

A standard desktop printer with multiple ink cartridges can accurately deposit a broad variety of biomaterials on microfluidic paper-based analytical devices (μPADs) which have been extensively applied to environmental monitoring and screening of food and beverage contamination. Finding ways to realize sample quantitative control by tuning the CMYK value, however, remains challenging. Herein, we studied the influence of the CMYK value on the ink volume jetted by ink cartridges. The regularity research on a single-color and two-colors was performed in two print mode-grayscale printing and color printing. The results demonstrated that the number of ink dots increased with the increase of the gray value and opacity value, which means that the amount of the bio-ink increases with the increase of the CMYK value. The 3,3',5,5'-tetramethylbenzidine-horseradish peroxidase-hydrogen peroxide, glucose oxidase-horseradish peroxidase and bull serum albumin-citrate buffer-tetrabromophenol blue systems were chosen as examples to prove the print regularity. Samples and assay reagents can be quantitatively deposited on a substrate by adjusting the CMYK value with as many as four ink cartridges. The present approach has been successfully applied to assay the targets in real serum samples, showing the potential application of the most common office piezoelectric printer in μPADs.

In situ-derived boron-doped graphene quantum dots can significantly improve the activity of boron carbide nanosheets for artificial N2 fixation and reduction with superior electrocatalytic activity (NH3 yield: 28.6 μg h−1 mgcat.−1 at −0.45 V vs. RHE; faradaic efficiency: 16.7%), high electrochemical stability, and high selectivity in 0.1 M HCl under ambient conditions.

The ultimate strength of stiffened panels under compressive loads is assessed by numerical simulations, in order to compare with tests made to investigate the influence on the ultimate strength of varying pit location, pit diameter and pit depth. The validated model is them used for a numerical study on the influence of pitting on the residual ultimate strength of stiffened panels by a series of non-linear finite element analysis. The parameters of pit position, diameter, number, depth, and corroded volume loss will be investigated for the stiffened panels subjected to axial compressive load with initial deformations. It is found that the pits will induce the buckling failure of stiffened panels. All parameters discussed in this paper have significant influence on the residual ultimate strength of the pitting corroded stiffened panel. A formula was derived by introducing the reduction of plate slenderness and column slenderness.

Thermally conductive polymer composites with satisfactory mechanical performances are highly required for practical thermal management applications as thermal interface materials. Herein, all-graphitized graphene aerogels with highly aligned graphene network are fabricated with graphene oxide hydrogels as the precursor by directional-freezing followed by freeze-drying and subsequent graphitization at 2800 °C, which exhibit excellent thermal and electrical conductions and superelasticity. Thanks to the vertically aligned conductance network composed by the graphitized graphene sheets, an epoxy composite with only 0.75 vol% of the high-quality graphene exhibits an excellent vertical thermal conductivity of 6.57 W/(mK), which is among the highest through-plane thermal conductivities of polymer composites at similar loading of carbon nanofillers, and more than 37 times higher than that of neat epoxy matrix. The thermally and electrically conductive composite also exhibits greatly improved storage modulus, compressive strength and compressive strain at break.

ZnO-deficient Zn2-xGeO4-x ceramics with 0.05 ≤ x ≤ 0.15 were synthesized because a ZnO secondary phase is formed in the stoichiometric Zn2GeO4 ceramics synthesized using micrometer-sized ZnO and GeO2 powders. The Zn1.9GeO3.9 ceramic sintered at 1000 °C showed a homogeneous Zn2GeO4 phase with good microwave dielectric properties: er of 6.8, Q × f of 49,000 GHz, and τf of −16.7 ppm/°C. However, its sintering temperature was still too high for it to be used as an advanced substrate for low-temperature co-fired ceramic devices. Therefore, various amounts of B2O3 were added to the Zn1.9GeO3.9 ceramics to reduce their sintering temperature. Owing to the formation of a B2O3-GeO2 liquid phase, these ceramics were well sintered at low temperatures between 925 °C and 950 °C. In particular, 15 mol% B2O3-added Zn1.9GeO3.9 ceramic sintered at 950 °C showed promising microwave dielectric properties for advanced substrates without the reaction with an Ag electrode: er = 6.9, Q × f = 79,000 GHz, and τf = −15 ppm/°C.

Metal-organic frameworks (MOFs), especially those made by biological molecules (bio-MOFs), have been proved to be prospective candidates for biomedical applications. However, a simple and universal bio-MOF to load different substances for precise targeting is still lacking. In this work, we propose a facile one-pot method to prepare a peptide-doped bio-MOF for general encapsulation and targeted delivery. This bio-MOF is constructed by 9-fluorenylmethyloxycarbonyl-modified histidine (Fmoc-His) as a bridging linker that coordinates with Zn2+ ions, denoted as ZFH. The Fmoc-His-Asp-Gly-Arg peptide (Fmoc-HDGR) can be easily doped into the ZFH structure with different ratios to modulate the targeting ability of ZFH-DGR. Containing both hydrophobic Fmoc and hydrophilic His moieties, this framework is compatible with encapsulating various types of payloads, including hydrophobic chemotherapeutic, hydrophilic protein, and positively/negatively charged inorganic nanoparticles. It has also been proved to be highly biocompatible and stable in circulation, exhibit the capabilities to target ανβ3 integrin overexpressed on tumor cells, and trigger drug release in a low pH microenvironment at the tumor site. As a proof of concept, Doxorubicin (Dox)-loaded ZFH-DGR (ZFH-DGR/Dox) demonstrated high cell selectivity between liver hepatocellular carcinoma (HepG2) cells and normal liver (L02) cells, which express high and low ανβ3 integrin, respectively. This selectivity endows ZFH-DGR/Dox precise treatment and low toxicity in Heps-bearing liver cancer mice. This work develops a de novo approach to construct a peptide-doped bio-MOF system for universal load, precise delivery, and peptide drug combination therapy in the future.

Sulfur quantum dots (SQDs) are a new kind of functional nanomaterial, but several challenges still exist in relation to their synthesis and application, such as low-yield and time-consuming synthetic methods, low photoluminescence quantum yields (PLQYs), and the non-selectivity of their detection mechanisms. Herein, we report the drastic enhancement of the fluorescence performance of water-soluble SQDs via the one-pot synthesis of size-focusing QDs using ultrasound microwave radiation. The synthetic period has been greatly shortened to 2 h via the present process. Notably, the proposed SQDs exhibit a highly stable emission wavelength with a record high PLQY of 58.6%. The mechanistic study indicates that size-focusing is a key factor relating to the proposed high-performance SQDs. As they also have robust stability, the proposed SQDs show a wide range of potential applications. Inspired by the characteristic properties of the SQDs and specific analytes, a simple SQD-based fluorescence sensing platform, via a redox-reaction-mediated mechanism, has been successfully developed for the rapid and selective detection of Ce(iv). In addition, this system has been effectively applied to some Ce(iv)-related biological assays, such as ascorbic acid (AA) analysis. This work is an important breakthrough in the SQD field, opening up avenues for solving the challenging problems relating to SQD-based probes, enriching the fundamental understanding of them, and greatly extending their applications, especially in biomedicine.

CuO-added 0.965(Na0.5K0.5)(Nb1-xSbx)-0.035BaZrO3 ceramics (0.00 ��� x ��� 0.10) were well prepared at 1070��C for 8 hours. And the effect of Sb5+ ions on the phase boundary variation and the corresponding piezoelectric properties were studied. It was found that the crystal structures varied from orthorhombic-tetragonal, orthorhombic-tetragonal-rhombohedral, orthorhombic-rhombohedral PPB and finally to rhombohedral structures of 0.965(Na0.5K0.5)(Nb1-xSbx)-0.035BaZrO3 with x value increasing, and the corresponding piezoelectric properties varied according to the variation of crystal structures. Particularly, the specimen with an Amm2 orthorhombic (11.1%) ��� R3m rhombohedral (88.9%) dominant PPB structure (x = 0.08) showed the highest d33 value of 415 pC/N and strain of 0.12% at 4.5 kV/mm.

Tip enhanced IR spectra and imaging have been widely used in cutting-edge studies for the in-depth understanding of the composition, structure and function of interfaces at the nanoscale. However, molecular monolayer sensitivity has only been demonstrated on solid/gas interfaces. In aqueous environment, the reduced sensitivity due to strong damping of the cantilever oscillation and background IR absorption extremely limits the practical applications of tip enhanced IR nanospectroscopy. Here, we demonstrate hypersensitive nanoscale IR spectra and imaging in aqueous environment with the combination of photoinduced force (PiF) microscopy and resonant antennas. The highly confined electromagnetic field inbetween the tip end and antenna extremely amplifies the photoinduced force to the detectable level, while the excitation via plasmon internal reflection mode minimizes the environmental absorption. A polydimethylsiloxane (PDMS) layer (~1-2 nm thickness) functionalized on the AFM tip has been successfully identified in water with antennas of different sizes. Sampling volume of ~604 chemical bonds from PDMS was demonstrated with sub-10 nm spatial resolution confirmed by electric (E) field distribution mapping on antennas, which strongly suggests the desired requirements for interfacial spectroscopy. This platform demonstrates for the first time the application of photoinduced force microscopy in aqueous environments, providing a brand-new configuration to achieve highly enhanced nanoscale IR signals, which is extremely promising for future research of interfaces and nanosystems in aqueous environments.

There is a continuing high demand to design effective sensors for the determination of heavy metal ions (HMIs) since they are hazardous to both human health and the environment. In this study, we reported a facile fluorescent sensor array for rapid discrimination of HMIs based on a single gold nanocluster (AuNC) probe. This AuNC probe was prepared by using 2-mercapto-1-methylimidazole (MMI) as a ligand and polyvinypyrrolidone (PVP) as a dispersing agent. The fluorescence emission of PVP/MMI-AuNC was observed to be closely related to the pH value of the aqueous solution, which displays yellow (λmax = 512 nm) and red (λmax = 700 nm) fluorescence at pH 12.0 and 6.0, respectively. Further experiments indicated that different HMIs can produce differential effects on the photoluminescence of PVP/MMI-AuNC and thus generate distinct fluorescent responses at 512 and 700 nm. On the basis of this phenomenon, a fluorescent sensor array based on the PVP/MMI-AuNC was then built by simply changing pH value in the sensor element. A total of seven HMIs had their unique response patterns and were successfully distinguished by hierarchical cluster analysis and linear discriminant analysis both in buffer solution and spiked water samples, achieving 100% identification accuracy. This study provides a simple and powerful fingerprinting sensing platform for multiple HMIs, showing broad application prospects in the field of environmental monitoring.