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This paper presents the development of a nonlinear vibro-acoustic modulation technique based on non-contact piezoelectric sensors to detect the crack progression of concrete subjected to both mechanical and thermal load. Two types of crack are investigated in the work including the isolated single crack induced by the three point bending test and distributed mapping cracks caused by heating treatment. Experimental results show that the damage index defined in the air-coupled wave modulation method – ultrasonic nonlinear parameter presents a positive correlation with the growth of single crack in bending test and the accumulation of mapping crack in thermal test. The sensitivity of developed method is validated through a comparison between the ultrasonic nonlinear parameter and two traditional linear parameters namely the phase velocity of Rayleigh wave and resonance frequency of vibrations. X-ray Computed Tomography (CT) technique and three-dimensional (3D) image reconstruction method are used to visualize microstructure of thermal damage. The CT images show that proposed nonlinear parameter is reliable and well correlated with the microstructural defects of concrete specimen. The repeatability of the air-coupled method is better than the contact method because the coefficient of variation of non-contact measurements is averagely about 43.2% of the contact measurements. Due to the advantage of removable characteristic of non-contact ultrasonic measurements, the developed air-coupled nonlinear wave modulation method could be promising for fast damage assessment of concrete structures in engineering practice.

To design and synthesize materials for alkaline hydrogen evolution is favorable for industrial hydrogen cycle operation. In this study, we present a facile approach to synthesize free-standing ruthenium-beryllium (RuBe) nanosheets, which possess amorphous phase state and associated with holey structures due to the molten method. The two-dimensional RuBe nanosheets exhibit improved activity than pure Ru counterpart and comparable properties to commercial Pt toward hydrogen evolution reaction in both of alkaline and neutral electrolytes. Based on the experiments and density functional theory calculations, it is suggested that the adsorption and dissociation of water molecules on Ru-based catalyst are much enhanced with the assistance of Be modulation, which are essential for the improved hydrogen production capability under alkaline condition. This work broadens the Ru-based catalyst family and may provide new insights for electrocatalyst development.

Reduced graphene oxide wrapped hollow molybdenum trioxide nanorods (MoO 3 @rGO) have been fabricated by a facile process. The MoO 3 @rGO shows improved lithium storage performance. It could deliver a high reversible capacity (842 mAh/g at 0.1 A/g), excellent cycling stability (778 mAh/g at 0.1 A/g after 200 cycles) and excellent rate capability (455 mAh/g at 2 A/g). The excellent electrochemical performance could be attributed as the special core (MoO 3 )/sheath (rGO) structure, which could accommodate the volume change of MoO 3 during lithiation/delithiation process. In addition, the rGO coating layer could improve the electronic conductivity of MoO 3 .

Heteroatom-doped carbon nanomaterials with well-defined porous are used as anode materials for SIBs due to their exceptional structural characteristics. In this work, porous N-doped carbon networks composed with ultrathin carbon nanosheets were synthesized via the direct pyrolysis of Vitamin B5. The content of nitrogen, specific surface area, porous structure of the N-doped carbon nanosheet networks were adjusted by changing reaction temperatures. The formation mechasim of the ultrathin N-doped carbon nanosheet networks was also proposed. The generation of calcium carbonate/calcium oxide used as a self-template renders the formation of the porous structure via thermal treatment. The optimized samples possess a superior lithium and sodium storage: 1534 mAh g −1 at 100 mA g −1 vs. Li/Li + and 335 mAh g −1 at 100 mA g −1 vs. Na/Na + , with nearly 100% cycling Coulombic efficiency, remarkable cycling retention and high rate capacity. Additionally, good electrocatalytic activity for ORR via a 4e −1 pathway determines that the resulting primary Zn-air battery showed high discharge power energy density (80 mW cm −2 ), high reversibility and stability over continuous cycles.

The photoluminescence (PL) and circularly polarized luminescence (CPL) of ((R)-1-phenyl-N-(pyren-1-ylmethyl)ethanamine) P-R were successfully modulated via fine-tuning and precise control of excited conformation of dimer/excimer by external stimuli. The resulting aggregation-induced emission (AIE)-active material (P-R) exhibited CPL with a low dissymmetry factor (∼10−4) in monomeric form, while demonstrating a prominent CPL signal with a higher dissymmetry factor (∼10−3) in thin solid films even without annealing processes.

An experimental study on a rotating detonation engine model using hydrogen/air mixture as propellant was conducted to analyze the initiation characteristics of detonation wave. Three ignition methods, including the ordinary spark plug, high-energy spark plug and thermal-jet tube, were used in the tests. The initiation process of rotating detonation wave was recorded and analyzed by a high frequency pressure measurement system and high-speed photographs. Operating range of the model engine was determined by series of experiments. Results indicate that the model engine could be successfully run by all the three ignition methods. Although the detonation formation time using spark plugs is quite stochastic, increasing the ignition energy can reduce the formation time of the detonation wave. Among the three ignition methods, thermal-jet provides the shortest detonation formation time. It is also found that the operating characteristic of the model engine is independent of the ignition device in the same operating condition. Three operation modes of the engine model have been observed, which are failed initiation of the detonation, unstable detonation and continuous rotating detonation. The experimental results show that the stable operating range can be extended by increasing the fuel mass flow rate.

The Sb encapsulated in S and N co-doped three-dimensionally (3D) interconnected macroporous carbon composite (denoted as Sb@S,N-3DPC) has been fabricated by using silica opals as hard template following a carbonization process. The structural and morphological characterizations reveal the uniform 3D-network structure with the Sb nanoparticles embedded homogeneously in the carbon spherical shell. The Sb@S,N-3DPC electrode shows a high reversible capacity of 482 mAh g −1 at 100 mA g −1 , displaying good capacity stability (~93% of the initial discharge capacity after 500 cycles at 100 mA g −1 ). The electrode displays superior rate capability and ultralong cyclability (255 mAh g −1 at 2 Ag −1 after 2000 cycles) and also reveals a good rate capability that maintains 160 mAh g −1 at 5 Ag −1 . The excellent electrochemical performance of the Sb@S,N-3DPC is attributed to the 3D-porous carbon network structure and uniform distribution of Sb nanoparticles in carbon matrix, enhancing the conductivity, holding the structure integrity, and thus improving the cycling performance of the anode material. In addition, sulfur and nitrogen co-doping introduced more defects and active sites to the carbon framework, thereby improving the interfacial adsorption and electrochemical behaviors.

Treatment of 1,2-C6H4(SiH3)(SiH3) (1) with Pt(dcpe)(PEt3)2 (dcpe = Cy2PCH2CH2PCy2) in dry toluene at room temperature in the ratio of 1:1 leads to the complex {1,2-C6H4(SiH2)(SiH2)}PtII(dcpe) (2), which can react with proton organic reagent bearing hydroxy group with low steric hindrance to form a tetra-alkoxy substituted silyl platinum(II) compound (3). The structures of complexes (2) and (3) were unambiguously determined by multinuclear NMR spectroscopic studies and single crystal X-ray analysis.

This paper investigates the degradation of concrete integrity under the rising temperature using a nonlinear ultrasonic second harmonic generation (SHG) technique based on a fully non-contact approach. The microscopic cracks accumulated during the course of thermal damage is then analytically and experimentally quantified by the elastic wave velocity inversion method and X-ray computed tomography (CT) technique, respectively. The nonlinear parameter calculated by the non-contact SHG technique not only shows a higher sensitivity to the damage growth than traditional macroscopic ultrasonic parameter such as wave velocity, but also presents an excellent correlation with microscopic quantified crack density by showing a proportionally increase with the propagation distance of ultrasonic waves. The experimental findings in this work indicate that the non-contact SHG technique can truly reveal the progressive microscopic cracking of concrete through the macroscopic nondestructive measurements and is suitable for the assessment of globally distributed damage with a high sensitivity and reliability.

The properties of spray-induced vortex-like structures for asymmetric pressure swirl atomizer were studied experimentally with different injection pressures. The high-speed Particle Imaging Velocimetry (PIV) was used to study the spray characteristics such as velocity and vorticity. The vortex centers were identified by velocity weighted vorticity. The translational velocity components of vortex centers were computed from its displacement divided by the time interval. For five different pressure conditions, the motion trajectories of vortex center were the same in an earlier period of spray, but were different in a later period of spray. The normalized translational velocity of vortex center and normalized time were introduced to compare with vortex ring model. The results indicated that the normalized axial translational velocity decreased with increasing normalized time, which converged to the predictions of the model in long time limit where α = −0.75 in the turbulent case. However, the results for the normalized radial translational velocity were different from the predictions of the model. The normalized radial translational velocity decreased with the increase of the normalized time when the injection pressure was lower than a critical value, but it obviously increased with the increase of the normalized time in case of the injection pressure higher than the critical value. Furthermore, the average vorticities at the vortex center were obtained and increased with the increase of the injection pressure. This study provides references for developing spray theory and improving injection technology.

A hollow cathode configuration was designed for a Grimm-type glow discharge atomic emission spectrometer (GD-AES). The operating conditions including the hollow cathode dimension, applied pulsed voltage and argon pressure, were optimized. The 10-μs pulses at 1.8 kV in a 3-torr discharge worked best. A pulsed hollow cathode Grimm discharge (HCG) offers several advantages: efficient excitation and ionization; high sensitivity; temporal spectral resolution; and rapid sample interchange. The capability of this source for the determination of elemental composition in metals, alloys and in solution residues is investigated. Samples used in this study included copper and steel standards.

A thermospray nebulizer was used as a sample introduction device for microwave plasma torch (MPT) atomic emission spectrometry (AES). Experimental parameters, including the power supplied to the MPT, the flow rates of support and carrier gases, the observation height, the sample uptake rate, the thermospray working temperature, the temperature of the aerosol spray chamber and cooling water were optimized. Under optimum conditions, the relative standard deviation (RSD) of 10 measurements for 21 elements is in the range 0.3–2.0%. The detection limits were improved in comparison with the ultrasonic nebulizer as sample introduction technique for MPT–AES. The inclusion of 20% methanol into the MPT showed there is no effect on the stability of MPT discharge. The technique can thus be held to have the potential for interface to reverse-phase HPLC systems.

A transient data acquisition system for flow injection analysis (FIA), high performance liquid chromatography (HPLC), and electrothermal vaporization (ETV) combined with ICP-AES multi-element instrumentation was developed and successfully applied to the analysis of different types of samples, including human serum, human hair and tea, for simultaneous multi-element determinations. The accuracy of the method was verified with hair reference material. Good agreement between the experimental results and certified values, and also satisfactory recoveries from standard additions, were achleved.

Over 100 hair samples were collected from the Xiamen area of south China, including 72 healthy people and 34 cancer patients, for the study of distinguishing cancer patients from others; another 64 hair samples were collected from patients with liver, stomach, lung, and miscellaneous cancers and were used for the discrimination analysis of different types of cancers, The samples were analyzed with ICP-AES for the simultaneous determination of several elements and with GFAAS for Se content after wet digestion. The average values of the element concentrations in the hair samples are presented. The results obtained were then analyzed with principal component analysis and partial least-squares methods, to distinguish cancer patients from others, and with an orthaganolization recurrence method to discriminate different types of cancers. The cancer patients could be completely distinguished from healthy people; while the misdiscrimination rates for the analysis of liver, stomach, and lung cancers are 15.8, 14.3, and 19.0%, respectively.

The determination of metal concentrations in fish with ICP-AES and FAAS was performed. Based on the metal concentrations found in fish collected from four regions of south China, principal component analysis was applied to a bioindicator study. The relationships between metal concentrations in fish tissues and those in seawater were studied by a simulated experiment. Using these relationships, the accumulation factors were determined, and the mean concentrations of Zn, Cd, Cu, and Pb in the coastal seawater of Min Jiang estuary, Dong Shan island, Me Zhuong island, and Hai Tan island were estimated.

Based on the M 2 -factor concept and the equivalence between a beam generated by a gaussian Schell-model (GSM) source and a mixed-mode laser (MML) beam, a simple method is presented to estimate the number of effectively oscillating modes and the corresponding weighting factors of MML beams simultaneously.