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MoS2 and nitrogen doped active carbon composite (MoS2/ANC) is fabricated to detect taxifolin and exhibits superior redox current response and decreased redox potential difference. Further investigation reveals that the kinetic process of the redox reaction of taxifolin on MoS2/ANC electrode is controlled by both adsorption and diffusion process. Under the optimum conditions, the redox peak currents linearly relate with the concentration of taxifolin in the range of 1 × 10−9–1 × 10−6 mol L−1, accompanied by the low detection limit (3 × 10−10 mol L−1). Meanwhile, outstanding selectivity, stability and repeatability are also obtained at MoS2/ANC electrode. At last, the proposed method is applied to quantitatively detect taxifolin in fructus polygoni orientalis and satisfactory results have been achieved.

Porous carbon derived from rice husk has been prepared and subsequently be used as carbon support to in situ fabricate hierarchical MoS2 microspheres. The X-ray powder diffraction characterization indicates that the graphite structure exists in the obtained rice husk carbon which is beneficial for the enhancement of the charge transfer speed. MoS2 microspheres on the surface of rice husk carbon present hierarchical structure with nanosheet subunit, and exhibits looser morphology than the individual MoS2 due to the lattice shrinkage. Based on the synergistic effect of MoS2 and the rice husk carbon, MoS2@RHC composite displays excellent lithium storage performance. The charge-transfer resistance of the MoS2@RHC composite is great lower than that of the individual materials. This result leads to the superior cycling stability and rate capability based on the favorable interface kinetics with faster lithium ion diffusion. The lithium charge-discharge mechanism of the composite is also further investigated. The log (peak current) versus log (scan rate) plot reveals that the current is predominantly controlled by the diffusion kinetics during the lithiation and delithiation process.

Transition metal elements (Ni, Cu, Mn, Co and Cr) have been doped into the host structure of molybdenum trioxide via in situ hydrothermal method. The characterizations indicate that Ni and Cu doping has no influence on the structure of the host MoO3 while Co and Cr doping not only cause the crystalline phase transformation but also leads to the morphology change of the doped MoO3. These crystalline and morphology alteration have great impact on the electrochemical performance of the doped samples. The electrochemical tests demonstrate that the specific capacitance and the rate capability are enhanced after Ni, Cu and Mn doping while decline after Co and Cr doping, which may be caused by the structure and morphology change of MoO3 as well as the formation of SEI (solid electrolyte interface) layer after Cr doping. The results manifest that metal ions doping has great impact on the electrochemical property of host materials.

A hierarchical nanocomposites of NiMoO4@Ni(OH)2 is fabricated via hydrothermal and electrodeposition method. The electrochemical tests performed using cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy display that the hierarchical NiMoO4@Ni(OH)2 nanocomposites exhibits superior supercapacitive performance to those of NiMoO4 and Ni(OH)2, respectively. The initial specific capacitance for NiMoO4@Ni(OH)2 is 1278 F g− 1 at a current density of 1 mA cm− 2. The Nyquist plot of the NiMoO4@Ni(OH)2 reveals low Rct and its EIS data fitted by Zsimpwin software matched well with the primary data.

MoS2 nanosheet arrays grown on functional pomelo peel derived carbon (PPC) is constructed via in situ self-assembly method. The obtained MoS2/PPC composite is further used to fabricate electrochemical sensor for taxifolin detection. The current response of taxifolin on MoS2/PPC is significantly enhanced due to the synergistic effect between MoS2 and PPC. It is found that the charge transfer impedance and the Ohmic resistance corresponding to MoS2/PPC are the lowest, indicating fast electron transfer rate and good conductivity. Further investigation reveals that the redox peak current is linearly related to the concentration of taxifolin in the range of 7 × 10−8–1 × 10−5 mol·L−1 and the limit of detection is calculated to be 2.3 × 10−8 mol·L−1 (S/N = 3). In addition, no obvious interfering phenomenonhas been observed in the detection process of taxifolin, demonstrating that MoS2/PPC presents good selectivity toward taxifolin determination.

Cobalt and zinc bi-metal organic frameworks (CoZn-MOF) derived from double metal hydroxides (CoZn-DMH) is synthesized on the surface of rice husk carbon via hydrothermal method. The obtained CoZn-MOF/RHC is then used as electrochemical sensor for dopamine detection. SEM and TEM characterization displays that the morphology of CoZn-MOF/RHC is different from CoZn-DMH, as well as the electrochemical performance. Further investigation reveals that the kinetic process of the redox reaction of dopamine on CoZn-MOF/RHC electrode is controlled by diffusion process. Under the optimum conditions, the redox peak current linearly relates with the concentration of dopamine in the range of 2 μM~0.8 mM, with the low detection limit of 0.67 μM. During the anti-interference experiment, CoZn-MOF/RHC exhibits good selectivity toward dopamine detection but inappreciable response for interferent.

Polypyrrole/ d -tartaric acid composite is successfully fabricated by homogeneous coating of a polypyrrole (PPy) layer around d -tartaric acid ( d -TA) nanospheres and the pyrrole (Py) quantity is adjusted. X-ray powder diffraction characterization demonstrates that the PPy is amorphous in PPy/ d -TA composite, which is beneficial for ion transfer. The specific capacitance of the polypyrrole/ d -tartaric acid electrode obtained with the ratio of [Py]/[ d -TA] = 1:1 is 200 F g −1 at a scan rate of 5 mV s −1 . Moreover, the polypyrrole/ d -tartaric acid ([Py]/[ d -TA] = 1:1) displays satisfactory electronic conductivity in EIS measurement. The electrochemical results indicate that the d -tartaric acid is a promising support for the fabrication of electrode in electrochemical energy-storage devices.

Different precipitants are employed to fabricate NiCoO 2 with various morphologies. X-ray powder diffraction characterization demonstrates that the NiCoO 2 products obtained using different precipitants display the same crystallization. The electrochemical performance display that the specific capacitance of the NiCoO 2 nanostructure obtained using urea is up to 328.5 F g −1 at a current density of 0.62 A g −1 in 2 M KOH aqueous electrolyte. The obvious redox peaks on the cyclic voltammetry curves show that the NiCoO 2 displays pseudocapacitor performance. The cycling stability reveals that the specific capacitance retains 95.2% after 1500 cycles at different current densities, indicating superior rate capability of the NiCoO 2 -urea electrode. These results indicate a promising potential application of NiCoO 2 for using as an effective electrode material in supercapacitors.

Hexagonal-MoO3/polypyrrole conductive hybrid is facilely prepared by wrapping a homogenous polypyrrole (PPy) layer around hexagonal-MoO3 (h-MoO3) prism via in-situ oxidative polymerization of self-assembled pyrrole monomer. The electrochemical performance of the obtained h-MoO3/PPy hybrid in different electrolytes is investigated. The cyclic voltammogram results at different scan rates show that the rate behaviors of h-MoO3/PPy in the three electrolytes improve in the order of Li2SO4

Nickel-based metal organic framework (Ni-MOF) and carbon nanotubes composite (Ni-MOF/CNTs) is constructed via in situ self-assembly of Ni-MOF in the presence of CNTs solution. The obtained electrode (Ni-MOF/CNTs) exhibits sensitive response toward the detection of taxifolin by significantly enhancing the redox peak currents and decreasing the peak-to-peak separation. Under the selected conditions, the peak current linearly relates with taxifolin concentration in the range of 4.0 × 10−8 ~ 1.0 × 10−5 mol L−1 with the detection limit of 1.33 × 10−8 mol L−1 (S/N = 3). Otherwise, the lithium storage results reveal that Ni-MOF/CNTs with enhanced conductivity exhibits benign cycling stability and rate capability, with coulomb efficiency around 100%. This Ni-MOF/CNTs electrode may lay the foundation for the Ni-MOF based materials in electrochemical application.

The rolling element bearings are extensively applied in rotating machines, and they are the most susceptible components in rotating machines. Early fault detection of bearings is to prevent machines from such typical failures and subsequent consequences. In this paper a detector based on Ensemble Average of Autocorrelated Envelopes (EAAE) is proposed to identify the early occurrence faults in rolling element bearings, of which the fault induced vibration signals are inevitably contaminated or masked by both additive background noise and random phase noise (or slippage between bearing components). To enhance the cyclostationary characteristics for fault detection, it utilizes the phase synchronization property of autocorrelation signals for aligning the cyclostationary signals in the lag domain to achieve an effective ensemble average which allows both types of random influences to be suppressed significantly. As a result, this detector shows very high performance of robustness in extracting the local fault signatures, which is verified by simulation signals and experimental investigations and benchmarked by the recent milestone method of Spectral Correlation (SC).

Uniform Co 3 O 4 @MoO 2 nanosheet arrays is fabricated through hydrothermal and electrodeposition method by virtue of the chemical-etching method. The electrochemical measurements show that the specific capacitance of 600 F g −1 at a scan rate of 2 mV s −1 for the Co 3 O 4 @MoO 2 hybrid is higher than both pristine MoO 2 and Co 3 O 4 . Moreover, the hybrid electrode with low resistance displays good cyclic stability of 83% retention after 1000-cycle charge/discharge. These results indicate that the as-prepared Co 3 O 4 @MoO 2 hybrid is a potential candidate used as electrode material in supercapacitors.

In this paper the depth-sensing indentation (DSI) testing was used to study the elasto-plastic behavior and damage evolution in the surface layers of 304 stainless steel subjected to low-cycle fatigue loadings. For this purpose, the load–penetration depth ( P − h ) curves on the surface layers of cyclically deformed specimens corresponding to various stages of fatigue process were measured, from which the indentation characteristic parameters ( HV , S , h r and W p ) were extracted to evaluate the surface elasto-plastic behavior of the stainless steel during cyclic deformation. Based on the indentation characteristic parameters, the basic mechanical properties ( E , σ y and n ) were estimated using Dao et al.’s analysis algorithm to establish the constitutive descriptions of the fatigued surface layers. In terms of the continuum damage mechanics, a new damage indicator parameter, the indentation plastic work ( W p ), was proposed to characterize the fatigue crack-initiation damage for the stainless steel, and its evolution character during fatigue cycling was analyzed. In this study the deformation microstructures formed in near-surface regions of fatigued specimens were also examined using OM and TEM techniques to provide the micro-mechanisms for the surface mechanical behavior and fatigue damage evolution. It is finally suggested that the DSI testing could provide a potential nondestructive evaluation method for the early detection of fatigue damage of engineering components and structures in alternating service conditions.

NiO with different morphologies were fabricated via hydrothermal method in different kinds of solvent. The morphology of the obtained NiO samples varied from nanoflakes to nanoparticles with the different volume ratios of water to ethanol. The electrochemical results showed that the specific capacitance of NiO-S5 obtained in ethanol was up to 1337.5 F g −1 at a current density of 0.62 A g −1 , which was greatly higher than that of the other samples. These results indicated that NiO-S5 had the superior electrochemical behavior which may be due to its small-size effect.

This paper focuses on the vibration behaviors of a hollow-shaft rotor system in presence of an open crack under inherent model uncertainties. Non-probabilistic interval variables are used to represent the uncertain parameters, which releases the high demands of probabilistic knowledge in the traditional methods. In modeling the shaft, local stiffness matrix of the cracked element is derived by using the neutral axis method. The periodic response of the rotor system is solved by combination of the finite element method (FEM) and the harmonic balance method (HBM). A simple mathematical function, termed as the uncertain response surrogate function (URSF), is constructed to estimate the vibrational response in various cases where different parametric uncertainties are taken into consideration. In order to verify the robustness and accuracy of the URSF, the bounds of estimated response are compared with those obtained from the classical methods. Results show that the surrogate function has good accuracy and robustness, providing an effective method and guidance for diagnosing crack in uncertain context.

This paper investigates the accelerating up transient vibrations of a rotor system under both the random and uncertain-but-bounded parameters. The Polynomial Chaos Expansion (PCE) coupled with the Chebyshev Surrogate Method (CSM) is used to analyses the propagations of the two categorizes of uncertainties. The output responses will possess the characteristics of both bounded quantities and statistical moments. As a hybrid non-intrusive uncertainty quantification (UQ) procedure, the deterministic rotor model is taken as a black box and will only be executed at some parameter points. A number of uncertain physical parameters are studied and the corresponding transient responses are presented. The accuracy and efficiency are verified by the Monte Carlo simulations (MCS) in combination with the scanning scheme and also other hybrid analysis framework. It will provide guidance for the accurate transient dynamic analysis of engineering problems with hybrid uncertainties.

The molybdenum-based metal organic framework (Mo-MOF) and polyaniline (PANI) composite is successfully prepared via in situ polymerization of aniline monomers. BET analysis reveals that the obtained Mo-MOF/PANI composite possesses larger specific surface area which is beneficial for its electrochemical performance. The charge-transfer resistance of the composite is greatly lower than that of the individual material. Meanwhile, the superior cycling stability and rate capability based on its favorable interface kinetics with faster charge transfer speed are also observed. The electrochemical kinetics investigated via electrochemical impedance spectroscopy reveals that Mo-MOF/PANI exhibits fast ion transformation rate.

NiS/CoS/NiCo2S4 microflower with hierarchical structure is successfully prepared via facile hydrothermal method. The supercapacitive performance displays that the specific capacitance is up to 513 F g−1 at a scan rate of 1 mV s−1. The obvious redox peaks on the cyclic voltammetry curves reveal pseudocapacitive performance of NiS/CoS/NiCo2S4. Furthermore, the glucose detection behavior of NiS/CoS/NiCo2S4 modified electrode (NiS/CoS/NiCo2S4/GCE) has also been performed. Amperometric study indicates that this non-enzymatic sensor displays excellent electrocatalytic performance to glucose. The glucose diffusion from the solution to the electrode surface is the kinetic control process. These results indicate a potential application of NiS/CoS/NiCo2S4 for using as an electrode material in supercapacitors and glucose sensor.

Polypyrrole/sodium carboxymethyl cellulose (PPy/CMC) nanospheres have been synthesized via in-situ oxidation polymerization of pyrrole in the presence of sodium carboxymethyl cellulose as a polymerization template. The size and shape of the composite are uniform with a diameter of about 100 nm. The electrochemical properties of the nanocomposite are investigated using cyclic voltammetry and galvanostatic charge–discharge measurements. The specific capacitance of PPy/CMC nanospheres can be as high as 184 F g −1 at a current density of 0.25 A g −1 . Moreover, the hybrid electrode showed good cyclic stability of 80% retention after 200 cycles of charge/discharge after introducing CMC as template. These results indicate a promising potential application of the PPy/CMC nanocomposite used as an effective electrode material in supercapacitors.

The graft copolymer of cross-linked starch/acrylonitrile was used for the dynamic adsorption of the copper ions in water and the experiments were carried out with the fixed bed. The penetration standard curve obtained by the fixed bed adsorption–penetration curve method was the S-type. An equation of y = y 0 + A e R 0 x which demonstrated the change of the concentration with the bed volume was fitted. The corresponding technical parameters such as flow rate, inlet ion concentration and the bed height were investigated to find the optimal adsorption conditions for the column. The results showed that with the flow rate was getting smaller, the inlet ion concentration, the bed height and the adsorption performance were getting lower, higher and better, respectively. However, the adsorption rate of the adsorbent became lower. Under ambient temperature the adsorption kinetics equation for the graft copolymer adsorbing copper ions in water was described as q = ( 86.9054 c + 41.9139 c 2 ) τ ( 1.3285 − 0.5716 c ) .

In this paper, a series of experiments including room-temperature low-cycle fatigue tests, instrumented indentation measurements, optical microscopy examinations, etc. were carried out to study the local mechanical properties and microstructures in particular zones of 304L SS welded joints in both the as-welded and cyclic straining conditions. An analytical algorithm proposed by Dao et al. [12] was utilized to estimate the basic mechanical properties ( E , σ y and n ) from the indentation load-depth data. It is shown that in the as-welded condition, the weld metal has a higher strength and strain hardening capacity but a lower stiffness than does the base metal, while the material within HAZ exhibits a significant gradient of the mechanical properties. A strain amplitude-dependent variation in the local mechanical properties in particular joint regions was also obtained. Optical microscopy examinations showed that the microstructure in particular zones of 304L SS welded joints was not only decided by the metallurgical condition resulting from the welding process, but also determined by the strain amplitude applied during cyclic straining. In this study, an empirical criterion for judging the fracture locations of a weldment based on the yield stress mismatch ratio was also introduced to assess the integrity of the present 304L SS welded joints subjected to low-cycle fatigue loadings. The research work performed in this paper would further expand the applications of instrumented indentation technique in fatigue strength analysis of welded components.

In this paper the instrumented micro-indentation testing (IIT) was used to study the mesoscopic elasto-plastic behavior of nickel-base superalloy GH4145/SQ subjected to cyclic straining at an elevated-temperature. For this purpose, a series of experiments including high-temperature low-cycle fatigue tests, instrumented micro-indentation measurements and OM (TEM) examinations were carried out. The characteristic parameters of indentation (C, hmax, S, hr, We and WP) during high-temperature fatigue failure process were determined from the experimental indentation load–depth (P–h) curves. The fatigue mesoscopic elasto-plastic properties such as E, σy and n were estimated using Dao et al.’s analysis algorithm [19], combined with the indentation characteristic parameters, and their distribution patterns were verified in a statistical sense. Microstructural examinations using both OM and TEM were performed to provide the micromechanisms for the fatigue mesoscopic elasto-plastic behavior of the superalloy during high-temperature low-cycle fatigue.

A series of experiments, including constant amplitude low-cycle fatigue tests, post-fatigue tension to failure tests, LOM (TEM) observations, and SEM examinations, were performed at room-temperature to investigate the effects of low-cycle fatigue damage on the static mechanical properties, microstructures and fracture behavior of 304 austenitic stainless steel. The changing characteristics of various static mechanical property parameters, including the strength parameters (σys and σult), stiffness parameter (E), ductility parameters (δ and φf) and strain hardening exponent (n) during fatigue damage process of the stainless steel were obtained experimentally and their micromechanisms were discussed by analyzing both the deformation microstructures and the fracture features of cyclically pre-deformed specimens. It was shown that the austenite/martensite transformation resulting from the accumulation of cyclic plastic strain was mostly responsible for the variation in the strength, ductility and strain hardening ability of the stainless steel during fatigue damage process. The depletion of the inherent ductility in the material due to fatigue damage evolution led to the ductile-to-brittle transition (DBT) in the fracture modes. Based on the macro/micro-experiments regarding the exhaustion of the ductility during fatigue damage, the ductility parameter was suggested as a damage indicating parameter for the present stainless steel in further studying the fatigue damage mechanics model as well as the residual fatigue life prediction method.

Zirconia supported platinum and tungstophosphoric acid (TPA) metal-acid bifunctional catalysts modified with lanthanum were prepared and tested in the reaction involving the production of branched-chain alkanes by skeletal isomerization of n -pentane. The prepared samples were characterized by XRD, FT-IR, H 2 -TPR and XPS. The catalytic performance was evaluated at 200 °C under atmospheric pressure. According to the conversion and selectivity a promotion effect of La on the activity of Pt-TPA/ZrO 2 was found and the optimal doping amount of La depended strongly on the Pt loadings. Simultaneously, cerium was also found to have the similar effect that was weaker than that of La.

The tetragonal prism SnO2 nanorods with the rutile structure have been successfully synthesized by a simple solvothermal method from high concentration precursors without any surfactant. Their sizes, morphologies and structure were studied by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), select-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The SnO2 nanorods obtained by the solvothermal method exhibit higher crystalline quality and better dispersion compared with the samples prepared by the hydrothermal method. Our results suggest that the solvent plays an important role to obtain high-yield SnO2 nanorods with high quality.

The photoluminescence (PL) properties of ZnO films fabricated by electrodeposition were investigated by using annealing treatment at various temperatures and in different atmospheres. The PL spectra are composed of a dominant UV emission and a weak green emission at room temperature. Our experimental reveals that the optimum annealing condition for UV emission exists at 400 °C in N2 atmosphere. A correlation between the UV PL intensity and Raman scattering intensity is first observed below 500 °C both in N2 and O2 atmosphere under resonant excitation. We suggest the 575 cm−1 Raman peak is strongly affected by a non-radiative center, and the intense UV emission of ZnO annealed at 400 °C in N2 atmosphere is due to the reduction of this center. Two different green emission bands are observed, which show different dependences of the PL intensity on the annealing temperature. According to the defect levels in the ZnO films and the analysis of the intensity dependences on annealing temperature and atmospheres, we suggest they are caused by interstitial oxygen (Oi) and antisite oxygen (OZn), respectively.