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This paper proposes an online prediction method for the roundness of grinding workpieces based on vibration signals. Vibration sensors are used to collect vibration signals during grinding, and wavelet packet denoising is used to preprocess original signals to obtain effective vibration signals. Then use time domain analysis and frequency domain analysis to extract features and normalize them to form feature vectors. The roundness of the finished workpiece is measured using a shape-measuring instrument and integrated with the feature vectors to generate a usable data set. The support vector machine (SVM) algorithm is implemented using A Library for Support Vector Machines (LIBSVM), and a prediction model is constructed. Use the data set to train the model and evaluate the accuracy of the model to verify the effectiveness of the model. The results show that the prediction accuracy of the prediction method can reach 92.86%, and it can better predict whether the roundness is qualified. [ABSTRACT FROM AUTHOR]

A novel porous polyoxometalate (POM)-based composite (Co4PW–PDDVAC) was prepared via the solidification of water-soluble polytungstate (Co4PW) on the polymeric ionic liquid dimethyldodecyl-4-polyethylene benzyl ammonium chloride (PDDVAC) via a cation-exchange reaction. The solidification was confirmed by EDS, SEM, FT-IR, TGA, and so on. The strong covalent coordination and hydrogen-bonding interaction between the highly active Co2+ of the Co4PW and the aspartic acid residues of proteinase K endowed the obtained Co4PW–PDDVAC composite with excellent proteinase K adsorption properties. Thermodynamic investigations indicate that the adsorption behavior of proteinase K was consistent with the linear Langmuir isothermal model, giving an adsorption capacity as high as 1428 mg g−1. The Co4PW–PDDVAC composite was applied in the selective isolation of highly active proteinase K from Tritirachium album Limber crude enzyme fluid. [ABSTRACT FROM AUTHOR]

The Modal Composition Beamforming (MCB) method can quickly achieve the localization of fast-rotating sound sources; however, its low resolution and unclear applied conditions severely limit its industrial application. This study aims to investigate the MCB-based high-resolution localization method for multiple rotating sound sources and apply it to the localization and identification of axial-fan blade-noise. In this paper, the Variational Bayesian Approximation (VBA) and the Subspace Variational Bayesian Approximation (SVB) methods are used to solve the MCB-based rotating sound power propagation (RSP) model, denoted as RSP-VBA and RSP-SVB, respectively. The effectiveness of the proposed RSP-VBA and RSP-SVB are experimentally validated for the first time. Compared to the conventional MCB method, the resolution is significantly improved, and the proposed high-resolution methods are even faster than the classical Rotating Source Identifier (ROSI) method in most conditions. More importantly, the applied condition of the MCB, RSP-VBA, and RSP-SVB methods is given and verified by using three evaluation indicators. Then a schematic of the applied condition with examples is provided. With the guide of the applied conditions, the RSP-VBA and RSP-SVB methods are applied to the blade-noise localization of various multiblade high-speed axial fans. [ABSTRACT FROM AUTHOR]

The rod-like pure MoO 3 and La-doped MoO 3 (L-MoO 3) sensitive materials were prepared by hydrothermal method. A series of structural analyses, including XRD, element mapping and XPS, revealed that La was uniformly doped into the crystal lattice of MoO 3. Furthermore, the gas sensitive studies showed that La doping significantly improved the gas sensitive performance of the sensors to triethylamine. The response value of L-MoO 3 sensor is 1148 to 50 ppm triethylamine, which is five times that of pure MoO 3 , and has outstanding stability and selectivity. Preliminary studies have shown that La doping enables the material to generate more active sites and larger baseline resistance, and the combination of these advantages contributes to structural sensitization and synergies to enhance the gas-sensitive performance of the L-MoO 3 sensors. This work prepared a high response TEA gas sensors, and verified the improvement of MoO 3 gas-sensitive performance by La doping. [Display omitted] • La-doped MoO 3 nanorods synthesized by hydrothermal synthesis process (L-MoO 3). • L-MoO 3 -based sensor has outstanding selectivity and sensitivity to TEA at 235 °C. • The response of 5 mol% L-MoO 3 to 50 ppm TEA (1148) is 5 times that of pure MoO 3. • La doping induces the formation of defects and increase of adsorbed oxygen content. [ABSTRACT FROM AUTHOR]

The acoustic imaging results in the diffuse field are seriously affected by reverberation. The acoustic source localization algorithms based on the free-field assumption will produce many artifacts in the reverberant environment. To achieve accurate acoustic source localization in a reverberant environment, a sound field morphological component analysis (SF-MCA) model and an enhanced alternating direction method of multipliers (ADMM) algorithm are proposed in this article. First, the solution of the inhomogeneous Helmholtz equation is analyzed to characterize the acoustic components. Second, Green’s function and plane-wave basis function serve as dictionaries for sparse representation of the acoustic signal in the frequency domain, and the corresponding decomposition coefficients are obtained by the enhanced ADMM algorithm. Finally, the accurate acoustic imaging results are realized in the reverberant chamber space with strong reverberation ($T_{20}=174.30\,\,\text {ms}$). Experiments demonstrate the validation of the proposed SF-MCA method. The acoustic imaging obtained by the proposed SF-MAC dereverberation model is far superior to the acoustic imaging that treats the reverberation as the general Gaussian noise. [ABSTRACT FROM AUTHOR]

This article proposes a variational Bayesian (VB) inference based on the nonsynchronous array measurement (NAM) (VB-NAM) method in order to obtain the fast and robust localization of low-frequency acoustic sources. To enlarge the aperture size compared with the prototype array, the NAM is performed to measure the acoustic pressures with low-frequency based on the forward power propagation model. The implementation of the NAM can be reformulated into a cross-spectral matrix (CSM) completion problem. Then, to solve the inverse problem of the NAM power propagation model, the VB inference based on the Student-t priors and Kullback–Leibler (KL) divergence optimization is proposed. The advantages of the proposed VB-NAM benefit from the optimization of matrix inversion and adaptive estimation of regularization parameters. The contribution of the adaptive parameter evaluation is to reduce the impact of multiple interferences (such as additive noise and the matrix completion error) in NAM. Finally, both simulations at 800 Hz and experimental results at 1000 Hz are presented to show the validation of the proposed VB-NAM method, even under the anisotropic Gaussian noise conditions. Algorithm performance and iteration process are analyzed to demonstrate the efficiency and robustness. [ABSTRACT FROM AUTHOR]

It is valuable to improve the resolution and speed of acoustic beamforming in real-time measurement, especially fault location, noise mapping, and so on. However, multiplication of the power transfer matrix takes much time in the iteration of the deconvolution algorithm. This article proposes a novel method based on the convolution approximation and GPU platform to obtain acoustic imaging with a high resolution quickly. First, the power propagation matrix is approximated by a symmetric Toeplitz block Toeplitz (STBT) matrix, which can transform the product of matrix and vector into the convolution of two smaller patterns. Three different convolution kernels are derived for the convolution operation, including 2-D variant convolution kernel, 2-D invariant convolution kernel, and 1-D separable invariant convolution kernel. Then, the regularization deconvolution algorithm with the convolution kernel is derived. Besides, the relation between approximation error, time cost, and setting parameters is discussed. The results show that the separable invariant convolution kernel can obtain the fastest imaging and relatively accurate localization, while the time consumption of the variant kernel is the highest. Simulations and experiments are operated on the CPU and GPU to make a comparison, which validates that our proposed deconvolution-GPU implementation can significantly improve the computation speed for the matrix on a large scale. [ABSTRACT FROM AUTHOR]

Baroreflex dysfunction is partly implicated in hypertension and one responsible region is the dorsal medulla oblongata including the nucleus tractus solitarius (NTS). NTS neurons receive and project glutamatergic inputs to subsequently regulate blood pressure, while G-protein-coupled metabotropic glutamate receptors (mGluRs) play a modulatory role for glutamatergic transmission in baroreflex pathways. Stimulating group II mGluR subtype 2 and 3 (mGluR2/3) in the brainstem can decrease blood pressure and sympathetic nervous activity. Here, we hypothesized that the chronic stimulation of mGluR2/3 in the dorsal medulla oblongata can alleviate hypertensive development via the modulation of autonomic nervous activity in young, spontaneously hypertensive rats (SHRs). Compared with that in the sham control group, chronic LY379268 application (mGluR2/3 agonist; 0.40 μg/day) to the dorsal medulla oblongata for 6 weeks reduced the progression of hypertension in 6-week-old SHRs as indicated by the 40 mmHg reduction in systolic blood pressure and promoted their parasympathetic nervous activity as evidenced by the heart rate variability. No differences in blood catecholamine levels or any echocardiographic indices were found between the two groups. The improvement of reflex bradycardia, a baroreflex function, appeared after chronic LY379268 application. The mRNA expression level of mGluR2, but not mGluR3, in the dorsal medulla oblongata was substantially reduced in SHRs compared to that of the control strain. In conclusion, mGluR2/3 signaling might be responsible for hypertension development in SHRs, and modulating mGluR2/3 expression/stimulation in the dorsal brainstem could be a novel therapeutic strategy for hypertension via increasing the parasympathetic activity. [ABSTRACT FROM AUTHOR]

The control effect of micro-vortex generators (VGs) on the instability of attached cavitation was investigated in a series of experiments. The micro-VGs, located at the leading edge of a NACA0015 hydrofoil, were used to alter the near-wall flow and control the attached cavitation dynamics. The effect of the nondimensional height of micro-VGs on the nondimensional cavity length was quantitatively evaluated by regression equations through response surface methodology. The micro-VGs increased the nondimensional cavity length. The counter-rotating streamwise vortices induced by micro-VGs had a rectifying effect on the near-wall flow and withstood the flow disturbance in the spanwise direction. Additionally, the micro-VGs partially suppressed Rayleigh–Taylor instability and Kelvin–Helmholtz instability arising from reverse flow underneath the cavity. Under a partial cavity oscillation (PCO) condition, the growth of sheet cavitation was highly two-dimensional in the spanwise direction, and the cloud cavity shedding had a strict periodicity with a smaller Strouhal number (St) than for the smooth hydrofoil. The shedding cloud cavity was captured in a single spanwise vortex core, which was advected toward the trailing edge of the hydrofoil. The transition from PCO to transitional cavity oscillation (TCO) occurred when the cavity length was larger than 0.8 of chord length. Under the TCO condition, the concave cavity closure line of sheet cavitation on the hydrofoil showed perfect symmetry and the St was nearly constant. As a result of our investigation, the micro-VGs have high potential to manipulate and control the attached cavitation dynamics. [ABSTRACT FROM AUTHOR]

Highlights • An alternative pointwise addition processor (PAP) is proposed for Golay compelementary waveforms. • The PAP performs similar to the pointwise minimization processor (PMP) put forward in the early work. • Theoretical analysis and simulations illustrate the tradeoff of PAP and PMP in terms of range sidelobe suppression and target detection probability. Abstract It has been an important technique to reduce sidelobes for processing nonzero Doppler target returns under Golay complementary waveforms. While the pointwise minimization processor in our early work shows an enhanced performance on the suppression of range sidelobes compared with existing approaches, it has a reduced detection probability to target with location uncertainties. In this paper, we present an alternative processing method which combines the radar returns in two separated pairs of Golay complementary waveforms through a pointwise addition processor. Our simulation result shows that this alternative method has a similar performance to that of the pointwise minimum processor for range sidelobes suppression and computational complexity but results in an improved target detection probability, with an acceptable decrease on the peak to peak-sidelobe ratio. [ABSTRACT FROM AUTHOR]

In this study, we investigate the effects of micro vortex generators (VGs) installed close to the leading edge of a quasi-two-dimensional NACA0015 hydrofoil under cavitating and non-cavitating conditions. Our aim is to improve physical insight into interaction mechanisms of the boundary layer with the formation and stability of partial cavities. Under non-cavitating conditions, the proposed micro VGs effectively suppress laminar separation. However, under cavitating conditions, even very small micro VGs within the boundary layer promote the formation of counter-rotating cavitating vortices. In comparison with the smooth hydrofoil surface (without micro VGs), the cavitation onset is shifted toward the leading edge. Additionally, classical "fingering structures" and Tollmien–Schlichting waves are no longer present. Since the onset of the cavity does no longer appear at (or close to) the laminar separation line, a novel onset mechanism is observed experimentally. The mechanism consists of stable vortex cavitation, followed by vortex break-down into bubbly structures that are finally accumulated into an attached cavity region. By reduction in the height of the micro VGs, a delayed vortex break-down is found, leading to an increase in the length of the cavitating vortex pattern. This allows for enhanced control on the cavity dynamics, especially with respect to the penetration depth of the re-entrant jet. As a result of our investigation, we conclude that well suited micro VGs show a high potential to manipulate and control cavity dynamics. [ABSTRACT FROM AUTHOR]

Abstract The iso -cis/trans-aminobenzopyranoxanthenes (iso -cis/trans-ABPXs), as one of popular leuco dyes, were investigated in solution or crystal phase. The introduction of benzo-pentacyclic-ester group in iso -cis/trans-ABPXs leads to remarkable multi-stimuli responsive behaviors, including protonation effect, photochromism and piezochromism with notable color changes. The iso -cis/trans-ABPXs show different in the responsive sensitivity and the iso -cis-ABPX is highly sensitive to environmental stimuli relative to the trans-form, which can be explained by their different C-H⋯O interaction and/or C-O bond length. Interestingly, as the ultraviolet light irradiation time increasing, the iso -cis/trans-ABPXs solution gradually becomes transparent and orange precipitates are achieved, which is identified as iso -ABPXs±. Multi-stimuli responsive behaviors on the iso -cis/trans-ABPXs provide a comprehensive insight into the chromogenic mechanisms of this type of materials, suggesting that they may be potential candidate materials for sensors and indicators. Graphical abstract Image 1 Highlights • The iso -cis/trans-ABPXs show remarkable color and spectral changes under different stimuli respectively. • The iso -cis -ABPXs is more sensitive to the stimuli due to the differences in structures. • The orange solid of iso -cis/trans-ABPXs± can be produced from iso -cis/trans-ABPXs solution under the UV light irradiation. [ABSTRACT FROM AUTHOR]

This study aims to investigate the mechanism of flow-induced effects on vibration signals from centrifugal pumps by combining computational fluid dynamics (CFD) and signal cyclostationarity. A pump vibration model is established as an amplitude-modulated (AM) model, and the modulation mechanism is elaborated in detail. A general AM model is mathematically analyzed with spectral correlation density and spectral coherence, and analytic solutions of modulation intensity are derived. Transient CFD simulations under design and off-design conditions are conducted to obtain the pressure pulsation in the volute and the radial fluid forces on the impeller. Then, vibration signals from the pump and motor feet with two acceleration transducers are processed by spectral coherence. The signature of second-order cyclostationarity is detected at the shaft rotating frequency and blade passing frequency (BPF). The mean spectral coherence is used to evaluate the intensity of the modulating signals produced by the flow-induced effects. Finally, the signal processing results are compared with the unsteady CFD results under design and off-design conditions. These comparisons show a good agreement. Therefore, this study confirms that the flow-induced signals calculated by CFD can be considered as modulating components for pump vibration signals. The results provide solid supporting theory for designing low vibration pumps. [ABSTRACT FROM AUTHOR]

Rare-earth fluoride materials can potentially boost the response performance of gas sensors owing to their unique carrier-regulation ability. In this study, YF 3 -modified mesoporous Co 3 O 4 (Y-Co 3 O 4 -350) nanorods with large specific surface area and abundant surface defects were fabricated through the heat treatment of serine-assisted, hydrothermally synthesized products at 350 °C. The Y-Co 3 O 4 -350-based sensor exhibited optimal triethylamine (TEA) gas-sensing behavior and yielded the highest response value ((R g − R a)/R a) = 93.2), with long-term stability and an appropriate response recovery time (18 s/36 s), at 170 °C. These splendid TEA-gas-sensing properties are attributed to the dual effect of morphology sensitization and electron sensitization, which together increase the adsorbed oxygen accumulated on the composite. In addition, DFT calculation finally determined the best adsorption location of TEA at the interface of Co 3 O 4 {112} plane and YF 3 {111} plane, where the adsorption energy of TEA is − 0.64 eV. YF 3 is therefore a promising modifier for enhancing the gas-sensitive properties of Co 3 O 4 semiconductor-based sensors. [Display omitted] • YF 3 introducing leads to electron–hole separation and surface defects. • YF 3 -composite-Co 3 O 4 -based sensor had excellent TEA sensitivity at 170 °C. • YF 3 composite Co 3 O 4 with mesoporous structure had huge specific surface area. • Morphology & electron sensitization promote adsorption of metastable oxygen species. [ABSTRACT FROM AUTHOR]

Although the reconstruction of functional 3D liver tissue models in vitro presents numerous challenges, it is in great demand for drug development, regenerative medicine, and physiological studies. Here we propose a new approach to perform perfusion cultivation of liver cells by assembling cell-laden hydrogel microfibers. HepG2 cells were densely packed into the core of sandwich-type anisotropic microfibers, which were produced using microfluidic devices. The obtained microfibers were bundled up and packed into a perfusion chamber, and perfusion cultivation was performed. We evaluated cell viability and functions, and also monitored the oxygen consumption. Furthermore, fibers covered with vascular endothelial cells were united during the perfusion culture, to form vascular network-like conduits between fibers. The presented technique can structurally mimic the hepatic lobule in vivo and could prove to be a useful model for various biomedical research applications. [ABSTRACT FROM AUTHOR]

The detachment of bubbles from an underwater nozzle inevitably generates distinct acoustic signals. This work proposes numerical simulation models to investigate the effect of different nozzle wall configurations on bubble formation and acoustic characteristics. A combination of large eddy simulation (LES) model and Ffowcs Williams–Hawkings (FW-H) equation is successfully applied to predict bubble acoustic pressures. The adaptive filtering techniques of signal processing are utilized in bubble acoustic analyses. In particular, transient spectrum based on time–frequency analyses can not only precisely count the bubbling period but also effectively measure the bubble sizes. The numerical results for bubble size are in good agreement with the theoretical data (less than 10% deviation). The main results of this research show that the structure of the nozzle wall plays a guiding role in vortex motion around bubbles. The bubble size also increases with the increase in exit-lip thickness, whereas the bubbling rate decreases. [ABSTRACT FROM AUTHOR]

In this study, the application of a Ni-free Zr 60.14 Cu 22.31 Fe 4.85 Al 9.7 Ag 3 thin film metallic glass (TFMG) was examined as an approach to retard the poor tribological properties of Ti-alloys for dental applications. The TFMGs were coated on biomedical Ti6Al4V substrate by single-target magnetron sputtering. The fretting resistance was assessed using a reciprocating tribo-tester against Si 3 N 4 counterpart in air and in artificial saliva. Bio-corrosion resistance of TFMG-coated Ti6Al4V samples was tested via electrochemical polarizations and electrochemical impedance spectroscopy in artificial saliva. Biocompatibility of the TFMG was tested in vitro, in comparison with that of the Ti6Al4V alloy. The results showed that this TFMG not only possessed 1.8–2.8 times higher fretting resistance than the Ti6Al4V alloy under various tribological conditions, but also lower bio-corrosion rate and superior passive film. In-vitro assessments of cytotoxicity and cell adhesion indicated that the TFMG has no any cytotoxicity and well-flattened cell adhesion morphology, as good as the Ti6Al4V alloy. The present Ni-free Zr-based TFMG is expected to improve the lifetime and quality of biomedical implants or devices for dental applications. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of rotating source localization to identify the axial fan noise with high spatial resolution methods. It exploits the on time-domain de-Doppler, and sparsity-based inversion and the convolution model to approximate the power propagation model of the rotating source. This work is also an extension of the previous paper of authors. But the focus of this study is the experimental investigation and application of actual data. To evaluate the performance of the proposed algorithm, a vortex generator is attached to the fan blade, creating discontinuities in the blade to simulate axial fan blade defects (cracks, holes, dust accumulations, etc.). The experimental data are shared as a data benchmark to promote further studies in the field of rotating acoustic localization. Compared with the state-of-the-art rotating Beamforming method (ROSI), the acoustic imaging results at various working frequencies for three different axial fans with different rotating speeds (RPM) are accurately identified and sparsely distributed. In addition, the power propagation model derived in the previous paper can be interpreted by a convolutional approximation model in this paper, and this technique can help to reduce the computational costs of proposed methods for real applications. The accuracy of the aerodynamic noise positions estimated by the proposed method are further proved to match well with the aerodynamic mechanism. • A practical implementation for the rotating sound sources localization in industrial axial fans is presented. • Two types of vortex generators (VGs) are attached to the blade, simulating the blade defects. • An explanation for the power propagation model based on the convolutional approximation is presented. • A data benchmark is established for peers to compare various rotating sound source localization methods. [ABSTRACT FROM AUTHOR]

Abstract: Acoustic imaging is a standard technique for mapping acoustic source powers and positions from limited observations on microphone sensors, which often causes an ill-conditioned inverse problem. In this article, we firstly improve the forward model of acoustic power propagation by considering background noises at the sensor array, and the propagation uncertainty caused by wind tunnel effects. We then propose a robust super-resolution approach via sparsity constraint for acoustic imaging in strong background noises. The sparsity parameter is adaptively derived from the sparse distribution of source powers. The proposed approach can jointly reconstruct source powers and positions, as well as the background noise power. Our approach is compared with the conventional beamforming, deconvolution and sparse regularization methods by simulated, wind tunnel data and hybrid data respectively. It is feasible to apply the proposed approach for effectively mapping monopole sources in wind tunnel tests. [Copyright &y& Elsevier]

Abstract: Near-field aeroacoustic imaging has been the focus of great attentions of researchers and engineers in aeroacoustic source localization and power estimation for decades. Recently the deconvolution and regularization methods have greatly improved spatial resolution of the beamforming methods. But neither are they robust to background noises in the low Signal-to-Noise Ratio (SNR) situation, nor do they provide a wide dynamic range of power estimation. In this paper, we first propose an improved forward model of aeroacoustic power propagation, in which, we consider background noises and forward model uncertainty for the robustness. To solve the inverse problem, we then propose a robust Bayesian super-resolution approach via sparsity enforcing a priori. The sparse prior of source powers can be modeled by double exponential distribution, which can improve the spatial resolution and promote wide dynamic range of source powers. Both the hyperparameters and source powers can be alternatively estimated by the Bayesian inference approach based on the joint Maximum A Priori optimization. Finally our Bayesian approach is compared with some of the state-of-the-art methods on simulated, real and hybrid data. The main advantages of our approach are of robustness to noise, a wide dynamic range, super spatial resolution, and non-necessity for prior knowledge of the source number or SNR. It is feasible to apply it for aeroacoustic imaging with the 2D non-uniform microphone array in wind tunnel tests, especially for near-field monopole and extended source imaging. [Copyright &y& Elsevier]

It was observed that the chemiluminescence intensity from the reaction of Ce (IV) with Tween20 was greatly enhanced in the presence of tryptophan, and the possible reaction mechanism was explored. Based on the reaction, a sequential injection procedure with chemiluminescence detection was developed for the determination of tryptophan. Under the optimum conditions, a linear dynamic range of 0.2-8.0 μM, a 3σ detection limit of 0.15 μM and a coefficient of variation of 0.7% at 3.0 μM level were obtained. The method was applied to the determination of tryptophan in beer and amino acid injections. [ABSTRACT FROM AUTHOR]

A stopped-flow sequential injection spectrophotometry for the simultaneous determination of Cu(II), Zn(II), Ni(II), and Mn(II), using an artificial neural networks methodology for multivariate calibration was developed. The experimental variables and network parameters were optimized and linear calibration curves were obtained in the concentration range of 0.1-2.0 mg L-1 at a sampling rate of 30 h-1. The proposed procedure was validated and the determination results for environmental water samples were statistically similar to those from the atomic absorption spectrometry. The analytical results obtained for reference samples of environmental water were in good agreement with the certified values. [ABSTRACT FROM AUTHOR]

Abstract: A new analytical method was developed for the simultaneous kinetic spectrophotometric determination of a quaternary carbamate pesticide mixture consisting of carbofuran, propoxur, metolcarb and fenobucarb using sequential injection analysis (SIA). The procedure was based upon the different kinetic properties between the analytes reacted with reagent in flow system in the non-stopped-flow mode, in which their hydrolysis products coupled with diazotized p-nitroaniline in an alkaline medium to form the corresponding colored complexes. The absorbance data from SIA peak time profile were recorded at 510nm and resolved by the use of back-propagation-artificial neural network (BP-ANN) algorithms for multivariate quantitative analysis. The experimental variables and main network parameters were optimized and each of the pesticides could be determined in the concentration range of 0.5–10.0μgmL−1, at a sampling frequency of 18h−1. The proposed method was compared to other spectrophotometric methods for simultaneous determination of mixtures of carbamate pesticides, and it was proved to be adequately reliable and was successfully applied to the simultaneous determination of the four pesticide residues in water and fruit samples, obtaining the satisfactory results based on recovery studies (84.7–116.0%). [Copyright &y& Elsevier]

Abstract: Chronic morphine administration induces functional and morphological alterations in the mesolimbic dopamine system (MLDS), which is believed to be the neurobiological substrate of opiate addiction. Our previous studies have demonstrated that peripheral electrical stimulation (PES) can suppress morphine withdrawal syndrome and morphine-induced conditioned place preference (CPP) in rats. The present study was designed to investigate if PES could reverse the cell size reduction induced by chronic morphine treatment in the ventral tegmental area (VTA), which is an important area of the MLDS. Immunohistochemical observations showed that the cell size of dopaminergic neurons in the VTA reduced significantly in the chronic morphine-treated rats with a concomitant decrease in the number of BDNF-positive cells compared to the saline-treated rats. A much milder morphological change, accompanying with an increased number of BDNF-positive cells, was observed in dopaminergic neurons in the rats that received repeated 100 Hz PES after morphine withdrawal. In another experiment, enzyme-linked immunosorbent assay (ELISA) reconfirmed a significant up-regulation of BDNF protein level in the VTA in the rats received 100 Hz PES after morphine abstinence. These results indicate that PES could facilitate the morphological recovery of the VTA dopaminergic cells damaged by chronic morphine treatment and up-regulate the BDNF protein level in the VTA. Activation of endogenous BDNF by PES may play a role in the recovery of the injured dopaminergic neurons in the morphine addictive rats. [Copyright &y& Elsevier]

Abstract: Glutamate receptors are known to be densely distributed in the forebrain rewarding circuits, and glutamatergic transmission is actively involved in the regulation of rewarding and reinstating effects of drugs of abuse. Here we investigated the possible involvement of the N-methyl-d-aspartate (NMDA) receptors in the reinstatement of extinguished morphine conditioned place preference (CPP) in rats. We found that previously extinguished morphine (3 mg/kg, i.p.) CPP was markedly reinstated by a priming injection of morphine (2 mg/kg, i.p.) or an acute environmental stressor (forced swim for 10 min), but not by the stress induced by a 24-h food deprivation. Parallel with this, protein levels of the NMDA receptor 2B subunit (NR2B) were elevated in the nucleus accumbens (NAc) and the hippocampus, but not the prefrontal cortex, of reinstated rats. Systemic administration of an NR2B selective antagonist ifenprodil (1, 3, 10 mg/kg, i.p.) attenuated the reinstatement induced by a priming morphine injection, although not by the forced swim. Ifenprodil (2.0 μg/rat) directly injected into the NAc shell or the CA1 region of the dorsal hippocampus produced a similar effect. These results indicate that the NR2B-containing NMDA receptors in the NAc and the dorsal hippocampus play a significant role in mediating the reinstatement of rewarding responses to morphine. [Copyright &y& Elsevier]

High blood pressure is a major risk factor of cerebro-cardiovascular outcomes. Blood pressure is partly regulated by the autonomic nervous system and its reflex functions; therefore, we hypothesized that pharmacological intervention in the brainstem that can regulate blood pressure could be a novel therapeutic strategy to control hypertension. We infused a group II metabotropic glutamate receptor (mGluR) antagonist (LY341495, 0.40 μg/day), using a mini-osmotic pump, into the dorsal medulla oblongata in young spontaneously hypertensive rats (SHRs), as this area is adjacent to the nucleus tractus solitarius (NTS), of which the neurons are involved in baroreflex pathways with glutamatergic transmission. Blood pressure was recorded for conscious rats with the tail cuff method. A 6-week antagonist treatment from 6 to 12 weeks of age slightly but significantly increased systolic blood pressure by >30 mmHg, compared to that in SHRs without treatment. Moreover, the effect continued even 3 weeks after the treatment ended, and concurred with an increase in blood catecholamine concentration. However, heart rate variability analysis revealed that LY341495 treatment had little effect on autonomic activity. Meanwhile, mRNA expression level of mGluR subtype 2, but not subtype 3 in the brainstem was significantly enhanced by the antagonist treatment in SHRs, possibly compensating the lack of mGluR signaling. In conclusion, mGluR2 signaling in the dorsal brainstem is crucial for preventing the worsening of hypertension over a relatively long period in SHRs, through a mechanism of catecholamine secretion. This may be a specific drug target for hypertension therapy. [ABSTRACT FROM AUTHOR]

• Enkurgram is proposed for modulation frequency extraction of fluid machinery. • Multiple non-overlapping frequency bands are selected by Enkurgram for demodulation. • Signal Characterization Ratio is proposed to quantify demodulation performance. • Enkurgram exhibits ideal demodulation capability in dealing with simulation signals. • Enkurgram shows good demodulation capability in applications to fluid machinery. Modulation frequency extraction of fluid machinery is significant, not only for the condition monitoring and fault diagnosis of cooperative targets in industrial fields but also for object detection and information prejudgment of non-cooperative targets in military applications. However, most existing demodulation methods tend to show poor performance due to the ubiquitous heavy Gaussian and non-Gaussian noise. Especially, narrowband demodulation methods such as Kurtogram are in a dilemma due to the signal characteristic of multi-wideband carrier wave in fluid machinery. In this paper, the Enkurgram is proposed for multiple demodulation frequency bands selection based on the combination of energy factor and shape factor. This method shows excellent demodulation capability in both simulation analysis and applications to fluid machinery. Firstly, an Amplitude-Modulated (AM) signal model with multi-wideband carrier wave is established. Unlike other narrowband demodulation methods, multiple non-overlapping frequency bands are selected by Enkurgram for demodulation based on the composite criterion of Spectral Energy (SE) and Spectral Kurtosis (SK). Moreover, the demodulation performance is quantified by the proposed Signal Characterization Ratio (SCR). Secondly, the effectiveness of Enkurgram is validated by simulation signals under different noise interference situations, including white Gaussian noise, stochastic impulse interference, periodic impulse interference, and contaminated modulation wave. Finally, the proposed method is verified by the actual signals from centrifugal pump and propeller, respectively. The analysis results prove that the Enkurgram has satisfactory demodulation capability in dealing with signals under low Signal-to-Noise Ratio (SNR) levels or with non-Gaussian noise, which is the Achilles' heel of SK-based methods. [ABSTRACT FROM AUTHOR]

• Proposed methods localize rotating monopoles at high rotation speed and low SNR. • The rotation blur and Doppler effect is removed by the de-Doppler Beamforming. • The ill-posed inverse problem is solved with high resolution. • Aerodynamic sound sources can be localized in the industrial fan experiment. The rotating-acoustic source localization has played an important role in rotary machine fault diagnosis, engine noise reduction and propeller recognition etc. To achieve high-resolution localization of fast rotating sources, this paper proposes an improved power propagation forward model of rotating acoustic source based on the equivalent source hypothesis. Then the ill-posed inverse problem derived from the forward power model is solved robustly by proposed two sparsity-based methods: the Least Absolute Shrinkage and Select Operator for Rotating-acoustic Sources (LASSO-RS) and Least Angle Regression for Rotating-acoustic Sources (LAR-RS). The contributions of this paper are that, at one hand, the improved forward model is indeed time-invariant for the fast-rotating source owing to the time-domain de-Doppler technique; at the other hand, high-resolution acoustic maps can be obtained by proposed LASSO-RS and LAR-RS thanks to the sparsity-based regularization, even under very low signal-to-noise ratio (SNR). Moreover, the proposed LAR-RS is the data-driven method, rather than the parameter-dependent method such as the LASSO-RS with careful selection of regularization parameter. In simulations and experiments, the proposed methods can robustly localize rotating monopoles in the condition of 3000 RPM rotation speed (50 Hz), −5 dB SNR, and 2500 Hz working frequency. [ABSTRACT FROM AUTHOR]

Cavitation failure often occurs in centrifugal pumps, resulting in severe harm to their performance and life-span. Nowadays, it has become crucial to detect incipient cavitation ahead of cavitation failure. However, most envelope demodulation methods suffer from strong noise and repetitive impacts. This paper proposes an adaptive Autogram approach based on the Constant False Alarm Rate (CFAR). A cyclic amplitude model (CAM) is presented to reveal the cyclostationarity and autocorrelation-periodicity of pump cavitation-caused signals. The Autogram method is improved for envelope demodulation and cyclic feature extraction by introducing the character to noise ratio (CNR) and CFAR threshold. To achieve a high detection rate, CNR parameters are introduced to represent the cavitation intensity in the combined square-envelope spectrum. To maintain a low false alarm, the CFAR detector is combined with the CNR parameter to obtain adaptive thresholds for different data along with sensor positions. By carrying out various experiments of a centrifugal water pump from Status 1 to 10 at different flow rates, the proposed approach is capable of cavitation feature extraction with respect to the CAM model, and can achieve more than a 90% detection rate of incipient cavitation and maintain a 5% false alarm rate. This paper offers an alternative solution for the predictive maintenance of pump cavitation. [ABSTRACT FROM AUTHOR]

Sound source visualization has been widely used in many scenarios such as aerospace, industrial production, and urban management. Sound source localization technology plays an essential role in the realization of sound source visualization. The imaging results and calculation cost are the primary considerations in the problem of sound source localization. This article proposes a subspace iteration integrated variational Bayesian (SVB) method to realize adaptive imaging of different sound sources. First, the proposed variational Bayesian (VB) method is based on total variation (TV) prior to balance the sparsity and smoothness of the imaging results. Second, the subspace optimization method in the probability measure space is integrated into the proposed SVB method to solve the involved ill-posed inverse problem. The proposed SVB method can significantly improve the calculation speed, especially for large-scale inverse problems. Finally, the speed and robustness of the proposed SVB method can be demonstrated according to the extensive results of simulation and experimental validation. [ABSTRACT FROM AUTHOR]

A series of organogelators based on L-phenylalanine has been synthesized and their gelation properties in various organic solvents were investigated. The results showed that these organogelators were capable of forming stable thermal and reversible organogels in various organic solvents at low concentrations, and the critical gel concentration (CGC) of certain solvents was less than 1.0 wt%. Afterward, the corresponding enthalpies (ΔHg) were extracted by using the van 't Hoff equation, as the gel–sol temperature (TGS) was the function of the gelator concentration. The study of gelling behaviors suggested that L-phenylalanine dihydrazide derivatives were excellent gelators in solvents, especially BOC–Phe–OdHz (compound 4). The effects of the solvent on the self-assembly of gelators were analyzed by the Kamlet–Taft model, and the gelation ability of compound 4 in a certain organic solvent was described by Hansen solubility parameters and a Teas plot. Morphological investigation proved that the L-phenylalanine dihydrazide derivatives could assemble themselves into an ordered structure such as a fiber or sheet. Fourier-transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (1H NMR) studies indicated that hydrogen bonding, π–π stacking, and van der Waals forces played important roles in the formation of a gel. [ABSTRACT FROM AUTHOR]

Background: Monocyte to high-density lipoprotein cholesterol ratio (MHR) is a novel inflammatory marker that has been used to predict various inflammation-related diseases. This study aims to explore the association between MHR and prevalent hyperuricemia in a rural Chinese population. Methods: 8163 eligible participants (mean age: 54.13 years, males: 45.71%) from northeast China were enrolled in this cross-sectional study between 2012 to 2013. MHR was determined as blood monocyte count ratio to high-density lipoprotein cholesterol concentration. Results: The prevalence of hyperuricemia was 12.86%. After adjusting for potential confounding factors, per SD increase of MHR caused a 25.2% additional risk for hyperuricemia, and the top quartile of MHR had an 82.9% increased risk for hyperuricemia compared with the bottom quartile. Additionally, smooth curve fitting and subgroup analyses showed a linear and robust association between MHR and prevalent hyperuricemia respectively. Finally, after introducing MHR into the established model of risk factors, the AUC displayed a significant improvement (0.718 vs 0.724, p = 0.008). Furthermore, Category-free net reclassification improvement (0.160, 95% CI: 0.096–0.224, P < 0.001) and integrated discrimination improvement (0.003, 95% CI: 0.002–0.005, P < 0.001) also demonstrated significant improvements. Conclusions: The present study suggests that MHR was positively and independently correlated with prevalent hyperuricemia among rural Chinese adults. Our results also implicate an important value for MHR in optimizing the risk stratification of hyperuricemia. [ABSTRACT FROM AUTHOR]

The span-wise obstacle on the suction surface of a hydrofoil has been verified to be an effective passive control method for cloud cavitation. The position of obstacle significantly influences the performance of cavitation control. In this research, we investigated the effect of obstacle position on attached cavitation control on the suction surface of a NACA0015 hydrofoil through response surface methodology. The cavitation types covered from sheet cavitation to partial and transitional cavity oscillations. We derived regression equations and built response surfaces to illustrate the quantitative relationship between individual factors (obstacle position, cavitation number, and angle of attack) and cavitation dynamic response parameters (cavity length, acoustic intensity, and energy flux). Sheet cavitation was effectively suppressed because the obstacle increased the pressure at the near-wall region. However, the obstacle would induce a shear cavitation when its position was too close to the leading edge of the hydrofoil. Under partial cavity oscillation conditions, the obstacle was consistently performed well in cloud cavitation control. The cavitation dynamic response parameters significantly decreased. Under transitional cavity oscillation conditions, the obstacle cannot suppress the cavitation because the transitional cavity oscillation was likely a system-inherent instability. This research is beneficial for a comprehensive understanding of cavitation control mechanism using an obstacle and for further industrial application of obstacle in hydraulic machinery to control cavitation. [ABSTRACT FROM AUTHOR]

Abstract Demodulation is a highly effective method for feature extraction of rotating machinery. Vibration/acoustic signal of rotating machinery carries substantial information that represents the mechanical equipment conditions. Therefore, the demodulation of vibration/acoustic signals is a key issue in fault diagnosis and target recognition. However, background noise enhances the difficulty of signal demodulation. This study proposes a novel demodulation method based on time-frequency analysis and principal component analysis (DPCA) to enhance demodulation performance under low signal-to-noise ratio (SNR). The periodic modulation wave signal is extracted by combining time–frequency analysis and principal component analysis (PCA). The effectiveness of the proposed method is verified by mean of simulation analysis and two real application cases. Firstly, monocomponent and multicomponent modulated simulation signals are used to test the performance of the proposed method. Secondly, the proposed method is applied to the vibration signals of the pump and acoustic signals of the propeller. Finally, the superiority of the proposed demodulation method is demonstrated by comparing the demodulation results with the kurtogram and cyclostationary analysis method under low SNR condition. Highlights • A novel demodulation method is proposed for rotating machinery based on time-frequency analysis and PCA. • The proposed DPCA method has well performance than kurtogram and cyclostationary analysis method in low-SNR. • The proposed DPCA method has well performance for passive acoustic detection by propeller acoustic experiment. [ABSTRACT FROM AUTHOR]

Infrared images have been widely used in many research areas, such as target detection and scene monitoring. Therefore, the copyright protection of infrared images is very important. In order to accomplish the goal of image-copyright protection, a large number of image-steganography algorithms have been studied in the last two decades. Most of the existing image-steganography algorithms hide information based on the prediction error of pixels. Consequently, reducing the prediction error of pixels is very important for steganography algorithms. In this paper, we propose a novel framework SSCNNP: a Convolutional Neural-Network Predictor (CNNP) based on Smooth-Wavelet Transform (SWT) and Squeeze-Excitation (SE) attention for infrared image prediction, which combines Convolutional Neural Network (CNN) with SWT. Firstly, the Super-Resolution Convolutional Neural Network (SRCNN) and SWT are used for preprocessing half of the input infrared image. Then, CNNP is applied to predict the other half of the infrared image. To improve the prediction accuracy of CNNP, an attention mechanism is added to the proposed model. The experimental results demonstrate that the proposed algorithm reduces the prediction error of the pixels due to full utilization of the features around the pixel in both the spatial and the frequency domain. Moreover, the proposed model does not require either expensive equipment or a large amount of storage space during the training process. Experimental results show that the proposed algorithm had good performances in terms of imperceptibility and watermarking capacity compared with advanced steganography algorithms. The proposed algorithm improved the PSNR by 0.17 on average with the same watermark capacity. [ABSTRACT FROM AUTHOR]

In this paper, the volume of fluid (VOF) model in conjunction with continuum surface force (CSF) model is applied to numerically investigate the single bubble formation process in the bubble columns. Meanwhile, the hybrid method (large-eddy simulation (LES) and acoustic analogy method) is used for bubble acoustic prediction. Experimental results provide a reliable validation of the numerical results. Adaptive filtering technique and time–frequency analyses are adapted for the numerical acoustic data at the gas velocity of 0.1 m/s. The spectrum and spectrogram approaches indicate that the numerical acoustic data covers two principal frequency components, in which, one is the bubble generation rate and the other is the natural frequency of volumetric bubble oscillation. By combining the studies of flow field and acoustic signals, volumetric bubble oscillation is found to be excited by an axial water jet up into the bubble, immediately following the bubble detachment. The results of this study lead to the proposition that numerical simulation method could be applied to well understanding of the physics behind the passive acoustic emission. [ABSTRACT FROM AUTHOR]

Spin qubits based on silicon metal-oxide semiconductor (Si-MOS) quantum dots (QDs) are promising platforms for large-scale quantum computers. To control spin qubits in QDs, electric dipole spin resonance (EDSR) has been most commonly used in recent years. By delocalizing an electron across a double quantum dots charge state, "flopping-mode" EDSR has been realized in Si/SiGe QDs. Here, we demonstrate a flopping-mode spin qubit in a Si-MOS QD via Elzerman single-shot readout. When changing the detuning with a fixed drive power, we achieve s-shape spin resonance frequencies, an order of magnitude improvement in the spin Rabi frequencies, and virtually constant spin dephasing times. Our results offer a route to large-scale spin qubit systems with higher control fidelity in Si-MOS QDs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two sp2-c -linked conjugated ingenious 2D COF are prepared via Knoevenagel reaction. • These two COFs exhibit favorable capture capacity towards different I 2 statements. • The capture mechanism of two sp2-c -COF towards I 2 is explored via DFT calculation. The ingenious design of sp2 -carbon-linked fully π-conjugated covalent organic frameworks (sp2 - c -COFs) with a periodic pore structure and high chemical stability, is vital. However, this remains a significant challenge owing to the poor reversibility of the coupling reactions. Here two novel isoreticular crystalline and highly porous two-dimensional (2D) sp2 - c -COFs (COF- p -NEU1 and COF- p -NEU2) are designed and synthesized via a base-catalyzed Knoevenagel polycondensation reaction based on the [ C 2 + C 3 ] topology diagram. As-prepared polycrystalline COF- p -NEU1 (with 1,3,5-tris(p-formylphenyl)benzene (TFP)) and COF- p -NEU2 (with 1,3,5‐tris‐(4‐formylphenyl) triazine (TFT)) exhibit long-range ordered structures, well-defined nanochannels, and favorable chemical stable, which endow the promising capture performance of COF materials. Meanwhile, the two sp2-c -COF can provide abundant functional units to promote the capture of I 2 due to introducing mass nitrogen species into the building block. Therefore, the two nitrogen-rich sp2 - c -COFs exhibit a high iodine uptake capacity for iodine vapor and iodine in cyclohexane with 4.58 g g−1 and for 1.31 g g−1 COF- p -NEU1 and 5.87 g g−1 and 1.51 g g−1 for COF- p -NEU2 at 348 K. The results of this study provide a potential path for the design and synthesis of novel sp2-c -COFs materials with high chemical stability and demonstrate the high potential of sp2-c -COF for the capture of radioactive contaminants. [ABSTRACT FROM AUTHOR]

Targeted design of new covalent organic frameworks (COFs) with specific functions to build multi-readout platform for environmental pollutant monitoring has been gaining increasing interest. Herein, a fluorescent phenanthroline-functionalized COF (PA-COF) with favorable pore structure and reactive nitrogen-containing functional groups is designed and synthesized, and in-situ growth of silver nanoparticles (AgNPs) in PA-COF is achieved to produce PA-COF-based nanocomposite (PA-COF@AgNPs). Phenanthroline facilitates the anchoring of Ag+ in the skeleton of COF material via strong coordination interaction, and the confinement of in-situ grown AgNPs on PA-COF structure provides excellent dispersibility. The formed silver amalgam in the skeleton of PA-COF@AgNPs with the presence of Mercury(II) can oxidize colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue product (oxTMB) quickly, inducing obvious absorbance/SERS signal enhancement and fluorescence quenching of PA-COF@AgNPs. A colorimetric/fluorescence/SERS triple-readout strategy is thus developed for Hg2+ sensing with high sensitivity and excellent accuracy. The present study offers a promising strategy to develop a multi-readout assay platform for monitoring hazardous pollutants based on the targeted fabricating of novel COFs with specific functions. • PA-COF@AgNPs composite is fabricated via in-situ growth of AgNPs on COF skeleton. • PA-COF@AgNPs composite can be served as a high active SERS substrate. • A PA-COF@AgNPs based triple-readout strategy is developed for Hg2+ monitoring. • The multi-readout strategy exhibits high sensitivity and excellent accuracy. [ABSTRACT FROM AUTHOR]

Krüppel-like factor 8 (KLF8) belongs to the Sp/KLF family of transcription factors. Recently, it is affirmed that KLF8 plays an important role in the regulation of epithelial-mesenchymal transition, which is a key process that occurs during cancer metastasis. Although the overexpression of KLF8 has been observed in several types of human cancers, the functional role of KLF8 in human bladder cancer remains unknown. Here, we investigated the effects of KLF8 knockdown on bladder cancer cell proliferation and migration in vitro. Lentivirus-mediated small interfering RNA (siRNA) targeting KLF8 specifically downregulated its expression in T24 and BT5637 bladder cancer cells. Knockdown of KLF8 significantly inhibit cell proliferation and colony formation. Cell cycle analysis showed that knockdown of KLF8 arrested T24 cells in the G0/G1 phase. Moreover, cell migration was attenuated in T24 cells after KLF8 knockdown. Furthermore, knockdown of KLF8 resulted in a reduction in vimentin and N-cadherin expression and an increase in β-catenin expression. These results indicate that KLF8 plays a crucial role in proliferation and migration of bladder cancer cells, and inhibition of KLF8 by siRNA may provide a potential therapeutic approach for gene therapy in bladder cancer. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MOF@iCOF@Tb composite is fabricated via in-situ polymerization and coordination. • The MOF@iCOF@Tb composite is used as sensitive fluorescence probe for NF detection. • The MOF@iCOF@Tb composite exhibits high NF capturing capacity. • The monitoring and capturing mechanism is also investigated via XPS spectra and DFT calculation. The construction of novel multifunctional nanocomposites is of interest because of their excellent proven detection and capture performance. Herein, a new type of porous material, UiO-66-NH 2 @TpTG Cl , is designed by combining a Zr-based metal organic framework, UiO-66-NH 2 , with a guanidine-based ionic covalent organic framework (iCOF), TpTG Cl. The UiO-66-NH 2 @TpTG Cl retains the high crystallinity and hierarchical pore structure of the MOF and iCOF, and has a surface rich in guanidine groups, and hence it has excellent hydrophilicity and is rich in positively charged sites; thus, the potential capacity of UiO-66-NH 2 @TpTG Cl for the capture of antibiotics with polar functional groups, such as norfloxacin, is excellent. Tb 3+ ions are then assembled onto the UiO-66-NH 2 @TpTG Cl skeleton. With the addition of norfloxacin to the composite, strong coordination between the carboxyl group of norfloxacin and the Tb3+ ions in UiO-66-NH 2 @TpTG Cl @Tb occurred, and the characteristic fluorescence emission of Tb3+ (5D 4 →7F 5) is enhanced by antenna and spatial confinement effect. Consequently, ratiometric fluorescence detection and capture of norfloxacin are realized using UiO-66-NH 2 @TpTG Cl @Tb. The linear detection range is 0.01–1 μM and the detection limit is 4 nM. Most importantly, UiO-66-NH 2 @TpTG Cl @Tb exhibits high capture capacity (251 mg g−1) and favorable capture efficiency (80.5%). Meanwhile, the mechanism is detailed explored through XPS spectrum and DFT calculation. We believe that this work will trigger the study of new iCOF-functionalized MOF composites and that it presents a promising strategy for simultaneous ratiometric luminescence monitoring and capturing of antibiotics from water. [ABSTRACT FROM AUTHOR]

• The SBL algorithm is used for sound source localization and quantification. • The SBL and IBF algorithms are compared in terms of effectiveness and robustness. • Advantages of SBL at low SNRs, low frequency are validated through experiments. The localization accuracy and acoustic quantification are the leading indicators of acoustic localization. It is difficult to reconstruct the acoustic field completely as the number of sources is larger than the number of microphones. To solve this problem, the sparse acoustic holography under the Bayesian framework is applied to acquire the phase and amplitude distribution of the acoustic field to achieve acoustic source localization. In this paper, a Sparse Bayesian Learning (SBL) algorithm is improved, which can not only perform acoustic localization quickly and accurately, but also quantize the sound source to achieve sparse acoustic holography. To verify the efficiency and robustness of the improved method, simulations and experiments with different sound sources and noise disturbances are performed in this paper to verify the superior performance of the SBL algorithm at low frequencies and low signal-to-noise ratios (SNR). [ABSTRACT FROM AUTHOR]

Abstract: The lamellar Fe/Al2O3 catalysts were prepared by sol–gel method, and then with these prepared catalysts, carbon nanotubes (CNTs) were synthesized by catalytic chemical vapor deposition (CCVD) method using C2H2 as precursor. The as-prepared CNTs and Fe/Al2O3 catalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and Raman spectrum. The results proved that the as-prepared CNTs actually existed in bundles. And the growth of CNTs bundles should be attributed to the lamellar catalysts, which supported the bottom growth mechanism of CNTs. The transition metal of Mo was not introduced in catalysts to produce CNTs bundles, which was different with others’ results. [Copyright &y& Elsevier]

Herein a nano-scale bimetallic Fe/Eu-MOF with a regular octahedral structure was synthesized for the first time. The synthesized Fe/Eu-MOF has both peroxidase-like activity and fluorescence properties. Fe/Eu-MOF can catalyze H 2 O 2 to oxidize the chromogenic substrate TMB to produce blue oxTMB, which has ultraviolet absorption at 652 nm. Unexpectedly, the generated oxTMB can effectively quench the fluorescence of the catalyst Fe/Eu-MOF at 450 nm. The quenching mechanism is mainly the internal filtration effect (IFE), accompanied by static quenching (SQE), Förster resonance energy transfer (FRET) and photoelectron transfer (PET). Fe/Eu-MOF has a high affinity for sodium pyrophosphate (PPi). PPi can be adsorbed to the surface of Fe/Eu-MOF, destroying the structure of Fe/Eu-MOF and inhibiting its catalytic activity, resulting in a decrease in UV absorbance and the decline of fluorescence quenching. In contrast, phosphoric acid (Pi) has almost no effect on the reaction system. Alkaline phosphatase (ALP) can catalyze the hydrolysis of PPi to Pi, thereby reducing the inhibitory effect of PPi. Based on this, we successfully constructed a dual-mode ALP sensor with high selectivity. The linear ranges based on the 652 nm absorption or the fluorescence detection are from 1 to 200 U/L, and the detection limits are 0.6 for the absorption method and 0.9 U/L for the fluorescence method, respectively. Schematic diagram of the influences of PPi and ALP on the fluorescence and peroxidase-like activity of Fe/Eu-MOF. [Display omitted] • Bimetallic Fe/Eu-MOF was produced by one-pot hydrothermal synthesis method. • The synthesized Fe/Eu-MOF has peroxidase-like activity and fluorescence. • The oxidation product oxTMB can quench the fluorescence of catalyst. • PPi can destroy the structure of Fe/Eu-MOF • Fe/Eu-MOF based sensor for dual-mode ALP detection. [ABSTRACT FROM AUTHOR]

Age-related white matter lesions (WML) are common, impact neuronal connectivity, and affect motor function and cognition. In addition to pathological nigrostriatal losses, WML are also common co-morbidities in Parkinson's disease (PD) that affect postural stability and gait. Automated brain volume measures are increasingly incorporated into the clinical reporting workflow to facilitate precision in medicine. Recently, multi-modal segmentation algorithms have been developed to overcome challenges with WML quantification based on single-modality input. We evaluated WML volumes and their distribution in a case-control cohort of PD patients to predict the domain-specific clinical severity using a fully automated multi-modal segmentation algorithm. Fifty-five subjects comprising of twenty PD patients and thirty-five age- and gender-matched control subjects underwent standardized motor/gait and cognitive assessments and brain MRI. Spatially differentiated WML obtained using automated segmentation algorithms on multi-modal MPRAGE and FLAIR images were used to predict domain-specific clinical severity. Preliminary statistical analysis focused on describing the relationship between WML and clinical scores, and the distribution of WML by brain regions. Subsequent stepwise regressions were performed to predict each clinical score using WML volumes in different brain regions, while controlling for age. WML volume strongly correlates with both motor and cognitive dysfunctions in PD patients (p < 0.05), with differential impact in the frontal lobe and periventricular regions on cognitive domains (p < 0.01) and severity of motor deficits (p < 0.01), respectively. Automated multi-modal segmentation algorithms may facilitate precision medicine through regional WML load quantification, which show potential as imaging biomarkers for predicting domain-specific disease severity in PD. • White matter lesions (WML) are common co-morbidities in Parkinson's disease (PD) • Periventricular WML significantly predicted UPDRS-III motor scores in PD • Frontal WML predicted cognitive impairment and frontal lobe dysfunction in PD • Automated segmentation algorithms quantify WML, facilitating precision medicine • Regional WML quantification may aid domain-specific clinical assessment in PD [ABSTRACT FROM AUTHOR]

• Cavitation characterization is realized by TSA and time-frequency analysis (TATF). • Extraction of carrier wave components caused by cavitation is the key issue. • TAFT exhibits better carrier wave extraction performance than STFT and WT. Cavitation detection is important in ensuring the reliability of fluid machinery, such as pumps. Vibration signal analysis is widely accepted as an effective tool in condition monitoring and fault diagnosis due to its ability to obtain substantial information and convenience of sensor arrangement. However, cavitation characterization based on vibration measurement is challenging because of the complicated underlying mechanism and low signal-to-noise ratio (SNR) of actual data. This study proposes a carrier wave extraction method for cavitation characterization by combining time synchronous average and time-frequency analysis (TATF) based on amplitude-modulated (AM) signal theory. The proposed method can reasonably measure cavitation severity by distinguishing time-frequency characteristics between different cavitation states. Compared with traditional vibration/acoustic signal monitoring or intelligent diagnostic techniques, cavitation detection based on TATF has the advantages of accurate classification and outstanding physical significance. First, cavitation state division criterion based on energy indicator is proposed. Its superiority is verified via comparison with the traditional criterion of hydraulic head. Second, the vibration signal model of pumps is established as an AM signal model, and the modulation mechanism is elaborated. Extraction of carrier wave components caused by cavitation is regarded as the critical issue in cavitation characterization. Then, TATF is described detailedly and its effectiveness is validated by simulation signals and actual data. Finally, the intelligent classification results of cavitation state by deep convolutional neural network (DCNN) demonstrate the superiority of TATF over short-time Fourier transform (STFT) and wavelet transform (WT). [ABSTRACT FROM AUTHOR]

Beamforming technology is an essential method in acoustic imaging or reconstruction, which has been widely used in sound source localization and noise reduction. The beamforming algorithm can be described as all microphones in a plane simultaneously recording the source signal. The source position is then localized by maximizing the result of the beamformer. Evidence has shown that the accuracy of the sound source localization in a 2D plane can be improved by the non-synchronous measurements of moving the microphone array. In this paper, non-synchronous measurements are applied to 3D beamforming, in which the measurement array envelops the 3D sound source space to improve the resolution of the 3D space. The entire radiated object is covered better by a virtualized large or high-density microphone array, and the range of beamforming frequency is also expanded. The 3D imaging results are achieved in different ways: the conventional beamforming with a planar array, the non-synchronous measurements with orthogonal moving arrays, and the non-synchronous measurements with non-orthogonal moving arrays. The imaging results of the non-synchronous measurements are compared with the synchronous measurements and analyzed in detail. The number of microphones required for measurement is reduced compared with the synchronous measurement. The non-synchronous measurements with non-orthogonal moving arrays also have a good resolution in 3D source localization. The proposed approach is validated with a simulation and experiment. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) co-crystal composed of 1, 3, 5-trifluoro-2, 4, 6-triiodobenzene and 4, 4′-trimethylenedipyridine via halogen bonding (I···N) was obtained on highly-oriented pyrolytic graphite, and was characterized by scanning tunnelling microscope supplemented by the density functional theory calculation. Its special structure at the interface was further compared with its three-dimensional (3D) co-crystal structure. No orderly structures were observed when Au (111) was applied. The 2D co-crystal grown on the interface is significantly different from the 3D co-crystal. This study is of vital significance in understanding the growth mechanisms of 2D functional co-crystals. • Achieving TMDP (C13H14N2) and 3F3I (C6F3I3) 2D/3D co-crystals. • Gold and highly-oriented pyrolytic graphite (HOPG) substrates used. • Compared to Au, HOPG substrate has an effect on the growth of 2D co-crystal. • Unsaturated/saturated 3F3I molecules present in the 3D TMDP/3F3I co-crystal. [ABSTRACT FROM AUTHOR]

Highlights • This paper presents a robust passive underwater acoustic detection method of propeller based on cyclostationarity and PCA. • The proposed detection method has better demodulation performance than classical demodulation methods under low SNR. • The proposed method provides a clearer characteristic frequency identification of marine propeller than classical ones in weak modulation intensity. Abstract Characteristic amplitude modulated radiated noise signals are generated as the propeller operates underwater. Generally, passive underwater acoustic detection is accomplished by processing the radiated noise of a marine's propeller. This study proposes a robust passive underwater acoustic detection method of a propeller by combining cyclostationary mechanism and principal component analysis (PCA). The proposed method can extract the characteristic frequency information of a propeller accurately. The effectiveness of the proposed method is verified according to simulated signals and real application cases. Both monocomponent and multicomponent modulated simulated signals are used to test the performance of the proposed method. The proposed method is then applied to the acoustic signals of propeller experiments and merchant ship propeller. Finally, the superiority of the proposed method is demonstrated by comparing the application results with the kurtogram and cyclostationary analysis method, during the extraction of the characteristic frequency of the propeller under low signal-to-noise ratio (SNR). The innovation of the proposed method not only realizes marine propeller detection from propeller acoustic signals but also has remarkable performance under low SNR. [ABSTRACT FROM AUTHOR]

The flow and acoustic characteristics of underwater gas jets exhausted from large vertical nozzles are experimentally investigated in this work with gas flow rates of 30–150 m3/h, nozzle widths of d = 10 mm, 20 mm, 30 mm, and 40 mm. A high-speed digital video camera is used to examine bubble behavior and flow regimes. Sound pressure is measured by two hydrophones and recorded by a digital audio tape recorder. The audio and video signals are synchronized to find out the relationship between sound and gas behavior. Experimental results indicate that the general behavior of gas exhausted into water is of periodical necking and expansion. Sound pressure peaks are mostly excited by necking in two ways: pinch-off and redial expansion. Necking itself is a kind of low frequency behavior, corresponding to strong low frequency sounds. Moreover, necking can force the growing bubble to oscillate and emit broadband sound. As the gas velocity increases, necking would happen more frequently, and gas jets would grow into larger volume in shorter time, and then the sound radiated from the gas jets would have higher frequency and larger amplitude. [ABSTRACT FROM AUTHOR]