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In this work, Au/Bi 2 Ti 2 O 7 /ITO ferroelectric diodes based on Schottky barrier were fabricated on ITO substrates by the sol-gel method. The device has a simple structure and good diode performance. Under UV light irradiation at 23.5 mW/cm2, the device exhibits an open-circuit voltage of 0.31 V and a short-circuit current of −0.0425 μA. It shows that the device has good optoelectronic properties. Au/Bi 2 Ti 2 O 7 /ITO ferroelectric diodes also exhibited behaviors similar to biological synapses, including long-term plasticity, short-term plasticity, paired-pulse facilitation, and spike-timing-dependent plasticity when stimulated by pulses. We also build convolutional neural networks and use the MNIST dataset for handwritten digit recognition. • The application of Bi 2 Ti 2 O 7 synapse in neuromorphic computing is reported for the first time. • The accuracy of handwritten digit recognition by neural network using Bi 2 Ti 2 O 7 synapse achieves 92.8 %. • The synaptic behavior of Bi 2 Ti 2 O 7 may be related to the migration of oxygen vacancies. [ABSTRACT FROM AUTHOR]

• A novel electromechanical assumption and associated equations was derived. • An exact analytical solution for the thick PZT disks was proposed. • An explanation of electromechanical coupling effect for PZT disks was investigated. • The experimental results are employed to examine the theoretical predictions. • The proposed method gives great prediction for three dimensional characteristics. A modified higher-order shear deformation plate theory (MHSDT) is proposed to predict the resonance frequencies and related mode shapes of piezoelectric disks of various thicknesses. The theory explicitly accounts for the effects of the electrical potential on the displacement of the disk. The equations of motion for the disk are derived using Hamilton's principle in conjunction with a variational approach. It is shown analytically that the distribution of the electrical field on the surface of the disk is quantitatively similar to the distribution of the sum of the total stresses within the disk. Thus, the deformation of the disk can be approximated directly from the stress distribution on the disk, thereby greatly simplifying the solution process. The validity of the proposed MHSDT is confirmed by comparing the solutions for the natural frequencies, displacement fields, and electric field distributions of the disk for various radius-to-thickness ratios and boundary conditions with those obtained using Reddy's third-order plate theory and COMSOL finite element simulations, respectively. The results show that the solutions obtained from the MHSDT method are consistently closer to the exact solutions than those determined using Reddy's third-order method. Finally, the linear relationship between the electric field and the flexural displacement of the disk is leveraged to design surface electrodes capable of exciting specific flexural mode shapes of the disk under a free boundary condition. The efficiency of the designed electrodes is experimentally demonstrated using an amplitude-fluctuation electronic speckle pattern interferometer (AF-ESPI). [ABSTRACT FROM AUTHOR]

Fifty-nine compounds, including nineteen previously undescribed iridoids (valeriananols A−S) and an undescribed alkaloid (5′-isovaleryl uridine), were isolated from the leaves and stems of Valeriana officinalis var. latifolia. Their structures were elucidated based on Mass spectrometry and NMR spectroscopy. The absolute configuration of valeriananols A−C, E−N, P, Q and S was determined by experimental and calculated electronic circular dichroism. Structurally, valeriananols A and B were two 1,3- seco -iridoids with a 3,6-epoxy moiety, valeriananols K and L were a pair of C-4 epimers, while valeriananol S was a 4′-deoxy iridoid glycoside. In addition, valeriananol P, stenopterin A and patriscabioin C exhibited significant inhibition on nitric oxide production with IC 50 values of 10.31, 3.93 and 8.69 μM, respectively. Furthermore, stenopterin A and patriscabioin C showed anti-proliferation activity on the MCF-7 cell line with IC 50 values of 17.28 and 13.89 μM, respectively. [Display omitted] • Twenty undescribed compounds were isolated from V. officinalis var. Latifolia. • Valeriananols A and B are two 1,3- seco -iridoids with 3,6-epoxy moiety. • Valeriananol S was a 4′-deoxy iridoid glycoside. • Three compounds showed significant inhibitory effects of nitric oxide production. • Stenopterin A and patriscabioin C showed cytotoxicity against the MCF-7 cell line. [ABSTRACT FROM AUTHOR]

An interesting hydrogen sensor prepared by an Al (3 at %)-doped SnO 2 (ATO) thin layer decorated with palladium nanoparticles (Pd NPs) is demonstrated herein. The related hydrogen detecting characteristics are systematically investigated. The elemental and intrinsic properties are characterized by high-resolution scanning electron microscopy (HRSEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The specific surface area and catalytic ability are remarkably enhanced due to the presence of Pd NPs on the ATO thin layer. This causes the considerable improvement of hydrogen sensing behaviors. Under introduced 1000 ppm hydrogen gas in air, a higher sensing response of 3152 with a corresponding response and a recovery times of 17 s and 4 s and a lower detectable concentration of 50 ppb H 2 /air are obtained at 225 °C for the studied Pd NP/ATO sensor. In addition, the studied sensor shows good repeatability and long-term stability. From a kinetic adsorption analysis, an activation energy about 43.6 kJ mol−1 is observed for this hydrogen detecting action. The studied Pd NP/ATO sensor also shows favours, e.g., simple device structure, easy production, lower consumed power, and a widespread sensing region of hydrogen gas content. [Display omitted] • A new Pd NP/ATO hydrogen gas sensor was fabricated and well studied. • Widespread sensing region on hydrogen gas content of the Pd NP/ATO sensor was observed. • The Pd NP/ATO sensor exhibited a higher sensing response and a very low detectable level. • The Pd NP/ATO sensor exhibited good repeatability and long-term stability. [ABSTRACT FROM AUTHOR]

The concrete-cored cement mixing (CCM) pile composite foundation is a practical technology for soft soil ground treatment. This paper proposed a theoretical analysis model for the CCM pile composite foundation under embankment in undrained condition which comprehensively considered the interaction between the various components of the CCM pile composite foundation. The working behavior and influencing factors of CCM pile composite foundation under the embankment was also investigated based on the proposed analysis model. The research results showed that: the embankment load was transferred from the outer soil column to the inner soil column. The formation of soil arch effect promoted the concrete core pile to undertake the majority of embankment load, which improved the working behavior of the CCM pile composite foundation under flexible foundation. There was a neutral plane at a certain depth below the ground surface, and the pile shaft above the neutral plane was under negative skin friction, moreover, the vertical stresses of the concrete core pile, cement mixing pile and the soil around the pile all reached the maximum value at the neutral plane. [ABSTRACT FROM AUTHOR]

Transition metal phosphates have proved to be promising electrocatalysts for hydrogen evolution reactions (HER) of water splitting, however, further increasing their active sites and catalytic activity remains a major challenge. Herein, accordion-like Co-MOF with layered structure was synthesized. After subsequent carbonization and phosphidization, lamellar heterostructured Co/CoP nanocrystals encapsulated in a P, N co-doped C matrix (Co/CoP@PNC) was obtained. Heterojunction provides abundant active sites and improves electron transfer rate. Additionally, the effect of phosphating degree on the electrocatalytic activity was studied. In the alkaline electrolyte, the current density of the optimized Co/CoP@PNC-10 for HER reached 10 mA cm−2 at overpotential of 137 mV in 1.0 M KOH, which was superior to most of transition metal-based electrocatalysts. This work provides new guidance for the design and development of transition metal-based electrocatalysts. Co/CoP heterojunction embedded in P, N co-doped C matrix (Co/CoP@PNC) was prepared through further carbonization and phosphidization, the optimized Co/CoP@PNC exhibited excellent catalytic activity for alkaline HER. [Display omitted] • With accordion-like Co-MOF as the precursor, Co/CoP heterojunction embedded in P, N co-doped C matrix (Co/CoP@PNC) was prepared through further carbonization and phosphidization. • The phase and catalytic activity of the sample are related to the phosphating degree. • The optimized Co/CoP@PNC-10 exhibited the best performance among the series, with an overpotential of 137 mV at a current density of 10 mA cm−2 for alkaline HER. • P, N co-doped C substrate and Co/CoP heterojunction promote the overall HER performance through synergistic effect. [ABSTRACT FROM AUTHOR]