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Ternary 0.552Pb(Ni1/3Nb2/3)O3-xPbZrO3-(0.448-x)PbTiO3 (PNN-PZ-PT) ceramics near the triple point compositions were fabricated by an improved two-step sintering method. The triple point composition 0.552PNN-0.135PZ-0.313PT ceramic has outstanding piezoelectric performance with piezoelectric coefficient d33 = 1200 pC/N. Its easy fabrication and low cost make this piezoelectric material an excellent candidate for high sensitivity sensors and ultrasonic transducers. The evolution of domain structures for ceramics with composition near the triple point provides deeper insight into the mechanism of ultrahigh piezoelectric properties of PNN-PZ-PT ceramics.

Relaxor-based ferroelectric single crystal with lower PbTiO3 content has complex phase transitions and mixed ferroelectric and relaxor characteristics, making it very challenging for the construction of Landau free energy expansion crucially used for theoretical investigation of this system. In this work, relaxor behavior in 0.78Pb(Mg1/3Nb2/3)O3-0.22PbTiO3 (PMN-0.22PT) single crystals was well suppressed through careful experimental design, leaving preserved single domain state for the Landau parameter extraction in this rhombohedral-phase composition. Using these extracted Landau free energy expansion parameters, energy profile and phase coexistence were theoretically studied and compared with those of PMN-0.30PT and PMN-0.36PT single crystals. Results show that rhombohedral phase dominates in PMN-0.22PT, and tetragonal phase dominates in PMN-0.36PT around room temperature. While, rhombohedral phase and tetragonal phase coexist in MPB composition PMN-0.30PT with small discrepancy of both free energies and polarization vectors.

To explore an appropriate intermediate temperature of heat treatment during the cold working of UNS N10003 alloy, the influence of heat treatment temperature, time, the induced deformation, the mechanical properties, and microstructures by the pre-stretching method was investigated systematically. The results showed that after heat treatment (performed at 760 °C, 6 h), the strength was not reduced, and the elongation was not improved efficiently. However, after only 30 min of heat treatment at 870 °C, their strength was efficiently reduced, and their elongation was substantially improved, reaching the original sample level. Moreover, no apparent changes were observed with the extension of heat treatment time. The morphology of the microstructures and fractures indicated that the recovery and recrystallization process occurred at the temperature of 870 °C during the heat treatment, which resulted in the residual stress relieving and microstructural reconstruction. Correspondingly, the fractographs were also transformed from cleavage to ductile. Therefore, the heat treatment during the cold working should be carried out at 870 °C, enhancing energy- and cost-efficient production of UNS N10003 alloy.

Phase and domain structures in ferroelectric materials play a vital role in determining their dielectric and piezoelectric properties. Ferroelectric thin films with coexisting multiple domains or phases often have fascinating high sensitivity and ultrahigh physical properties. However, the control of the coexisting multiple domains is still challenging, thus necessitating the theoretical prediction. Here, we studied the phase coexistence and the domain morphology of PbTiO3 epitaxial films by using a Landau–Devonshire phenomenological model and canonic statistical method. Results show that PbTiO3 films can exist in multiple domain structures that can be diversified by the substrates with different misfit strains. Experimental results for PbTiO3 epitaxial films on different substrates are in good accordance with the theoretical prediction, which shows an alternative way for further manipulation of the ferroelectric domain structures.

Bismuth telluride-based materials are the most celebrated thermoelectric (TE) materials near room temperature. However, for the n-type bismuth telluride-based materials, the traditional powder metallurgy (PM) method, such as grinding and ball milling, can induce strong donor-like effect. The strong donor-like effect boosts the carrier concentration [Formula: see text] and the carrier thermal conductivity [Formula: see text], leading to the deterioration of both electrical and thermal performance. Herein, the basal deformation (BD) has been performed in the n-type Bi2Te3-based materials to introduce weak donor-like effect. The BD crystalline bulks were obtained through sintering the stacked crystals, which had been heavily deformed on the (00[Formula: see text] plane. The BD process optimizes the carrier concentration [Formula: see text] and improves the power factor (PF). Meanwhile, the lattice thermal conductivity [Formula: see text] is suppressed due to the enhanced grain boundary scattering. Consequently, a peak ZT of 1.0 at 380 K has been achieved in Bi2Te[Formula: see text]Se[Formula: see text], which is 24% and 30% higher than that of the original zone-melting (ZM) ingot and the polycrystalline sample by PM. This study sheds light on the further TE performance enhancement of bismuth telluride-based materials via introducing the weak donor-like effect.

Chlorobenzene is considered an essential organic synthesis intermediate and a precursor for the generation of persistent organic compounds in the waste disposal process, for which accurate detection of gaseous chlorobenzene can further help understand and control various chemical processes and effectively reduce pollution. Differential optical absorption spectroscopy is a reliable online method for detecting gaseous chlorobenzenes. It is crucial to investigate the effect of temperature on the optical absorption of the chlorobenzenes to quantify chlorobenzenes more precisely at various temperatures. A method to fix the effect of temperature variation on absorption spectra of chlorobenzene is initially proposed in this study, and it gave accurate concentrations. The proposed method can effectively improve the accuracy of chlorobenzene concentration measurements with an inverse concentration deviation of 3.2 % or less. The differential absorption cross sections at various temperatures are studied to understand how chlorobenzene absorption cross sections vary with temperature. Such a study is also helpful in reducing the concentration inversion errors induced by the variation of absorption cross sections of chlorobenzene with temperature. A novel method of introducing the binary function of the differential absorption cross sections with respect to wavelength and temperature is also proposed. The fitting of the binary function is done by downscaling functions at fixed wavelength and fixed temperature,respectively. Both fitting approaches obtained continuous differential absorption cross sections in the 201-220 nm wavelength band and 288-473 K temperature range, along with less than 2.74 % deviation in the concentration inversion measurements. Finally,based on the temperature specificity of the shape of the differential absorption cross sections,we developed another method using differential absorption spectroscopy for the simultaneous measurement of temperature and concentration, with a temperature prediction error of less than 1.89 %. This method is favorable to the applications of differential absorption spectroscopy in simultaneous measurement of temperature and concentration.

Two-phase flow is commonly used in many aspects of industrial production, such as the mixed transport of oil and gas in petroleum exploitation and the feeding of coal powder or coal water slurry to coal-fired boilers. In these situations, it is necessary to measure the two-phase flow in real time and then adjust various parameters in order to achieve high efficiency, energy-saving, and safe production. The ultrasonic method is widely used to measure two-phase flow because of its various measurement approaches, wide range of measurable parameters, insignificant effect on the flow field, and its capacity for continuous online measurement. In this Review, the principles, characteristics, application scope, and research examples of different ultrasonic methods used in two-phase flow measurement are summarized, their advantages and disadvantages are compared, and the future development trends are forecast, which will play a positive role in the development of two-phase flow measurement.

Temperature-dependent dielectricity and polarization of [001]C-oriented 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 relaxor-based ferroelectric single crystals were studied by using a combined method of the X-ray diffraction, dielectric spectrum, polarization-electric (P-E) field hysteresis loops, and the Landau-phenomenological theory. Results show that the room-temperature rhombohedral phase experiences a rhombohedral-monoclinic-tetragonal coexisting state, then transforms to tetragonal phase, and finally to cubic phase during the zero-field-heating process. The six-order Landau-type thermal expansion parameters for the tetragonal phase were determined by using the typical characteristics at the cubic-tetragonal phase transition in the temperature range from 91 °C to 113 °C. The calculated dielectric curve, polarizations, and P-E loops fit well with the experimental results. The phase stability and piezoelectricity are further studied and compared with those of the PMN-0.36PT single crystal. The provided methods and obtained Landau parameters can be used for further studies on the relaxor-based ferroelectric single crystals.

Background and purpose Hydrogen sulfide donors can block the cardiovascular injury of hyperhomocysteinemia. H2 S also lowers serum homocysteine in rats with mild hyperhomocysteinemia, but the pharmacological mechanism is unknown. The present study investigated the mechanism(s) involved. Experimental approach ApoE-knockout mice were fed a Paigen diet and L-methionine in drinking water for 16 weeks to create a mouse model of atherosclerosis with hyperhomocysteinemia. H2 S donors (NaHS and GYY4137) were administered by intraperitoneal injection. We also assayed the H2 S produced (by methylene blue assay and mito-HS [H2 S fluorescence probe]), cystathionine γ lyase (CSE) mRNA and protein expression, and CSE sulfhydration and nitrosylation and its activity. Key results H2 S donor treatment significantly lowered atherosclerotic plaque area, macrophage infiltration, and serum homocysteine level in the mouse model of atherosclerosis with co-existing hyperhomocysteinemia. mRNA and protein levels of CSE, a key enzyme catalyzing homocysteine trans-sulfuration, were down-regulated with hyperhomocysteinemia, and CSE catalytic activity was inhibited. All these effects were reversed with H2 S donor treatment. Hyperhomocysteinemia induced CSE nitrosylation, whereas H2 S sulfhydrated CSE at the same cysteine residues. Nitrosylated CSE decreased and sulfhydrated CSE increased its catalytic and binding activities towards L-homocysteine. Mutation of C252, C255, C307, and C310 residues in CSE abolished CSE nitrosylation or sulfhydration and prevented its binding to L-homocysteine. Conclusions and implications Sulfhydration or nitrosylation of CSE represents a yin/yang regulation of catalysis or binding to L-homocysteine. H2 S donor treatment enhanced CSE sulfhydration, thus lowering serum L-homocysteine, which contributed in part to the anti-atherosclerosis effects in ApoE-knockout mice with hyperhomocysteinemia.

Variations in the single nucleotide polymorphisms (SNPs) of the oxytocin receptors (OXTR) indicate individual differences in stress response, social behavior, and psychopathology, but very few paper mentioned OXTR as part of the mechanism linking exposure to air pollution and poor social interactions. The authors investigated the moderating role of Oxytocin receptor (OXTR) rs53576 polymorphism in the relationship between PM

This paper presents a novel neural network adaptive sliding mode control (NNASMC) method to design the dynamic control system for an omnidirectional vehicle. The omnidirectional vehicle is equipped with four Mecanum wheels that are actuated by separate motors, and thus has the omnidirectional mobility and excellent athletic ability in a narrow space. Considering various uncertainties and unknown external disturbances, kinematic and dynamic models of the omnidirectional vehicle are established. The inner-loop controller is designed based the sliding mode control (SMC) method, while the out-loop controller uses the proportion integral derivative (PID) method. In order to achieve the stable and robust performance, the artificial neural network (ANN) based adaptive law is introduced to model and estimated the various uncertainties disturbances. Stability and robustness of the proposed control method are analyzed using the Lyapunov theory. The performance of the proposed NNASMC method is verified and compared with the classical PID controller and SMC controller through both the computer simulation and the platform experiment. Results validate the effectiveness and robustness of the NNASMC method in presence of uncertainties and unknown external disturbances.

LaAlO3-doped Bi0.5Na0.5TiO3-BaTiO3(BNT-BT) lead-free piezoelectric ceramics with compositions near the rhombohedral–tetragonal morphotropic phase boundary (MPB) were prepared and investigated. The ...

In this paper, through analyzing Tc bearing by the theory of Hydrodynamic lubrication, the unsteady Reynolds equation of Tc bearing under the dynamic-state condition is initially established. The formula of Tc bearing’s liquid-film dimensionless stiffness coefficient and damping coefficient is derived. Furthermore, two kinds of the distribution curves of Tc bearing’s liquid-film dimensionless stiffness coefficient, damping coefficient against Tc bearing’s eccentricity ratio and width-diameter ratio are displayed respectively, and the stability criterion of liquid film is worked out and the angular speed of instability of bearing shaft is calculated. Overall, conclusions are drawn: downhole system improves the entire system’s stability by enhancing the stiffness of bearing shaft itself. The improvement of the stability of bearing shaft itself, which can be done by altering the structure of Tc bearing and adopting better spiral flutes and ellipse groove can strengthen the whole system’s stability. The high width-diameter ratio of Tc bearing increases the liquid film’s stiffness coefficient and damping coefficient of Tc bearing. The rotational rate of rotary table is lower than half of that of the supporting system of Tc bearing.

In this paper, we developed a rapid and safe method based on packed-fiber solid-phase extraction (PFSPE) system coupled with gas chromatography-mass spectrometry for the determination of four phthalate esters (PAEs), diethyl-o-phthalate (DEP), dibutyl-o-phthalate (DBP), di (2-ethylhexyl) phathalate (DEHP), di-n-octyl phthalate (DNOP), in urine samples. The PAEs in urine samples (500μL) were rapidly cleaned up from urines using polystyrene (PS) nanofibers packed micro-columns fitted on a PFSPE pretreatment device, which can process up to 12 samples simultaneously in 5min. Under optimum conditions, satisfied recovery and relative standard deviation values (RSDs) were in the range of 80.4-111.7% and 1.5-10.9%, respectively. The limits of detection (LOD) and the limits of quantification (LOQ) were ranged from 0.1 to 0.5ngmL-1 and 0.5-2ngmL-1, respectively. The well controlled matrix effect was also evaluated by comparing the signal response of the pure PAEs standards dissolved in methanol with the signal response of PAEs in the urine matrix. This new method was successfully applied to determine four PAEs in urine samples of overweight and normal-weight children, and an association between phthalates in urines and obesity was observed. Thus, the method seems to be a useful tool for monitoring of the level of urinary phthalate esters and also to support an evidence for further reasearch of obesity.

The detection of vitamin D in complex samples is challenging because of the instability of vitamin D in sample preparation. To resolve this problem, packed-fiber solid-phase extraction (PFSPE) has been successfully developed for the pre-treatment of samples containing vitamin D2 (D2) and vitamin D3 (D3) in dairy products. Based on PFSPE, vitamin D could avoid oxidation because of the shorter extraction time. The adsorbent materials, polystyrene/polypyrrole (PS/PPy) nanofibers, were prepared by electrospinning of PS and in situ polymerization of PPy on the surface of PS nanofibers. The linearity was within the range of 1-2000 ng mL−1 in dairy solution, and the recoveries were 91.9-109.1% with a relative standard deviation (RSD) < 13.6%. Therefore, the prepared method could be used for the detection of D2 and D3 in dairy products.

Enhancing the mechanical quality factor, Qm, in ferroelectrics is one of the most critical issues for high-power devices, such as therapeutic ultrasonic transducers, large-displacement actuators, and high-frequency transducers. Although previous results have indicated that Qm could be improved through acceptor doping, the mechanism behind this effect is still a mystery, and there have been few reports on the optimization of energy loss in ultrahigh piezoelectric materials such as relaxor-PbTiO3 (PT) single crystals. In this work, we investigate the energy loss associated with various vibration modes in Mn-doped Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIN–PMN–PT:Mn) single crystals and compare with their undoped PIN–PMN–PT counterpart. We find that Q15, Q24, and Q33 in PIN–PMN–PT:Mn, respectively, undergo 160%, 100%, and 80% enhancements, thus demonstrating very large extrinsic contributions with unusual anisotropies in the Qm enhancement. Such a strong anisotropy is strongly interlinked with the orientation of the internal bias Ei and the charged domain walls. Our results provide some fundamental understanding of domain-engineered ferroelectric materials and materials-by-design for high-performance low-loss devices.

Phase transitions of Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 (PMN-0.34 PT) have been studied by using dielectric constant variations, polarization-electric field hysteresis loops, and polarizing light microscopy (PLM). Even without the assistance of electric field, orthorhombic (O) phase exists in the [001]C-oriented PMN-0.34 PT single crystals during the heating process, which is confirmed by the polarizer/analyzer extinction angle from full-angle in situ PLM observation combined with the grayscale image analysis. The phase transition sequence is monoclinic (MC) → O → MC → tetragonal (T) → cubic (C), which is different from the commonly accepted MC → T → C sequence. The existence of the O phase accompanies with much enhanced dielectric and piezoelectric performance, which indicates a new mechanism to produce large piezoelectricity in PMN-PT single crystals.

Sludge water was recycled using an ultrafiltration (UF) system. In order to control membrane fouling, three typical Fe(II)-activated peroxymonosulfate (PMS) processes: Fe(II)/PMS-UF (FPUF), 1/4Fe(II) × 4/PMS-UF (F4PUF) (adding Fe(II) in small increments four times), and Fe(II)/thiosulfate/PMS-UF (FTPUF) (adding Fe(II) after complexing with thiosulfate), were employed as UF pretreatments. Their mitigating effects of UF membrane fouling caused by sludge water are systematically discussed and compared. The results showed that FTPUF system had the best membrane fouling control effect. The F4PUF system was more suitable for long-term operation than FPUF due to its lower irreversible resistance. The pretreatments can effectively remove contaminants from sludge water through the dual effects of coagulation and oxidation. Specifically, coagulation removed most of the particles and macromolecular organic matter. Oxidation effectively decomposed fluorescent and UV-absorbing organic components, and reduced bacterial proliferation on the membrane surface. Concentrations of 2-methylisoborneol and geosmin in FPUF permeate were dramatically increased, which was mainly due to the rupture of algal cells in sludge water. Both adhesion force date and extended Derjaguin–Landau–Verwey–Overbeek theory indicated that the pretreatments significantly reduced interactions between the membrane–organic colloid and cake layer–organic colloid. In contrast, the stronger membrane–organic colloid interaction was a major contributor to membrane fouling. The mitigation of irreversible fouling was mainly attributed to the fact that oxidation enhanced the hydrophilicity of the organic colloids, thereby reducing the Lewis acid–base interaction energy. The results demonstrated the potential application of different Fe(II)-activated PMS processes as pretreatments for membrane fouling control during sludge water treatment.

Cyanobacterial hepatotoxins which are produced and released by bloom-forming cyanobacteria may threaten the safety of drinking water for human beings and animals. Microcystinase (MlrA) catalyzes the first and most important step for biodegrading hepatotoxic microcystins (MCs) and nodularin (NOD), which hydrolyzes the cyclic hepatotoxin into the linear hepatotoxin as the first product. Here the recombinant MlrA of Sphingopyxis sp. USTB-05 for biodegrading hepatotoxins was firstly purified and its activity was also investigated. The purification process of MlrA was comprised of four steps, affinity purification of glutathione S-transferase (GST)-tagged MlrA, thrombin cleavage of GST tag, GST tag removal and thrombin removal with the benzamidine sepharose. The purified recombinant MlrA was found to have a strong ability to catalyze hepatotoxins, and initial microcystin-LR (MC-LR) of 19.9 mg/L and NOD of 25.2 mg/L were removed within 10 min and 12 h at the protein concentration of 60 mg/L, respectively. The results indicated that the enzyme MlrA with a high activity could be purified and obtained with the biotechnology process of expression and purification described here, which is very important in further studies on the enzyme structure and the enzymatic mechanism for biodegrading hepatotoxins.

Microcystinase (MlrA) catalyzes the first and most important biodegradation step of hepatotoxic microcystin-LR (MC-LR) produced and released from cyanobacterial cells, and the underlying catalytic mechanism is not completely understood yet. MlrA was postulated previously to be a metalloprotease with an active site of H260AIH263NE265, a variant of the common metal-binding motif of HEXXH. Through comparison with representative modes in HEXXH-containing metalloproteases, molecular dynamics simulation, homology modeling, and docking, the active sites of MlrA involved in the MC-LR biodegradation by Sphingomonas sp. USTB-05 were predicted. Site-directed mutants of MlrA were constructed for verification then. The results show that MlrA is likely not a metalloprotease, but a glutamate protease belonging to type II CAAX prenyl endopeptidases. Combined with the biodegradation of MC-LR by MlrA and its mutants, a complete enzymatic mechanism for MC-LR biodegradation by MlrA is proposed: Glu172 and His205 activate a water molecule facilitating a nucleophilic attack on the Adda-Arg peptide bond of MC-LR; Trp176 and Trp201 contact the carboxylate side chain of Glu172and, by raising its pKa potentially, accelerate the reaction rates; His260 and Asn264 (located in the previous postulated active center of H260AIH263NE265) function as an oxyanion hole to stabilize the transition states. This study reveals the enzymatic mechanism of MlrA for catalyzing MC-LR in both the representative modes and the experiments of site-directed mutagenesis.