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Bimetallic lined pipe (BLP) has been increasingly used in offshore and subsea oil and gas structures, but how to identify the invisible inner defects such as liner wall thinning and interface debonding is a challenge for future development. A nondestructive testing (NDT) method based on pulsed eddy current testing (PECT) has been proposed to face these difficulties. The inspection of the BLP specimen (AISI1020 base tube and SS304 liner) is implemented from outside of the pipe by using a transmitter–receiver-type PECT probe consisting of two induction coils. By simplifying the BLP specimen to stratified conductive plates, the electromagnetic field interaction between the PECT probe and specimen is analytically modeled, and the probe inspection signals due to liner wall thinning and interface debonding are calculated. In order to highlight the weak response (in microvolts) from the liner, the inspection signals are subtracted by the signal, which is calculated in the case of only having a base tube, yielding differential PECT signals. The peak voltage of the differential signal is selected to characterize the liner wall thinning and interface debonding due to its distinguishable and linear variation. Experiment verification is also carried out on a double-walled specimen simulated by a combination of a Q235 casing pipe and SS304 tubes of different sizes. The experimental results basically agree with the analytical predictions. The peak value of the PECT signal has an ascending and descending variation with the increase in the remaining liner wall thickness and debonding gap, respectively, while the negative peak value shows opposite changes. The peak value exhibits a larger sensitivity than the negative peak value. The proposed method shows potential promise in practical applications for the evaluation of the inner defects in BLP lines. [ABSTRACT FROM AUTHOR]

The over-extraction of groundwater has resulted in seawater intrusion and the southward migration of the saltwater interface, gradually deteriorating the groundwater quality in the Weibei Plain. In this research, groundwater samples were gathered from 46 monitoring wells for shallow groundwater during the years 2006, 2011, 2016, and 2021. The hydrochemical features of regional groundwater and the factors influencing the issue were subjected to statistical analysis. Additionally, the assessment of spatiotemporal variations in groundwater quality was conducted using the customized entropy-weighted water quality index (EWQI) method. The relationship between groundwater over-extraction and the southward intrusion of the saltwater interface was compared and analyzed. The results of this paper revealed that the Weibei Plain has been in a state of long-term over-extraction of groundwater from 2000 to 2021, with an average annual over-extraction of 118.49 million m3. The groundwater depression cone areas in the northern part of the study area increased from 3,247.37 to 4,581.34 km2 from 2006 to 2021, with the center of the cone experiencing a drop in groundwater level from -22 to -85 m. The saltwater interface shifted southward by 711.71 km2 from 2006 to 2021. In groundwater, the high concentrations of TH, TDS, and Cl- were primarily related to the seawater intrusion, while higher concentrations of NO3- were mainly determined by frequent agricultural production, industrial wastewater, and domestic sewage discharges. The groundwater hydrochemical types in the study area transitioned from predominantly HCO3 Ca-Mg type in 2006 to HCO3-Na type and SO4 Cl-Ca Mg type in 2021 due to seawater intrusion. The results of PCA and HCA show the effects of seawater intrusion, human activities, and rock weathering on groundwater hydrochemistry. The evaluation results based on the EWQI revealed that the average value of the samples in 2021 was 101.36, which belonged to Class IV water quality standards, representing the poorest water quality among the 4 years. The southward migration of the saltwater interface led to the deterioration of groundwater quality in the groundwater depression cone areas, which gradually worsened from 2006 to 2021. The maximum increase in EWQI value was 174.68 during the period, shifting from Class III water quality to Class V water quality. Groundwater quality remained relatively better in the western and southern regions which were less affected or unaffected by seawater intrusion. The results of the study can provide a certain reference value for the sustainable management of groundwater resources and the management of groundwater pollution and seawater intrusion in the Weifang City area in the future. [ABSTRACT FROM AUTHOR]

Abstract: Sn1−x RE x O2−x/2 (RE=Y, La, Gd and Nd) nanorods have been prepared by annealing the as-obtained products from microwave-induced KCl-assisted solution combustion reaction. The phase evolution in the synthesis process was investigated by an X-ray diffractometer. Accordingly, the possible growth mechanism of Sn1−x RE x O2−x/2 nanorods was discussed based on oriented attachment by polar forces. The results showed that the Sn0.8Y0.2O1.9 nanorods were rutile-structured single crystals with 8–12nm diameter and 100–200nm length. Proper addition of KCl into the redox mixture solution is critical to the formation of Sn1−x RE x O2−x/2 nanorods. The approach is convenient, inexpensive and efficient for the high yield preparation of Sn1−x RE x O2−x/2 nanorods. [Copyright &y& Elsevier]

Abstract: Y2O3:Eu3+ nanophosphors were fabricated by direct thermal decomposition of monohydrate yttrium europium propionates, which can be facilely obtained via cocrystallization. The composition and structure of the cocrystallized product were confirmed by X-ray diffractionmetry (XRD), simultaneous differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) as well as inductively coupled plasma mass (ICP-MS) spectrometry. The effects of decomposition temperature on the resultant microstructures such as crystallinity, particle size and particle dispersibility were investigated by XRD and transmission electron microscopy (TEM). The dependence of their luminescent properties on decomposition temperature was also studied by fluorescence spectrophotometry. The results showed that the microstructures and luminescent intensities of Y2O3:Eu3+ nanophosphors could be tuned by varying calcination temperatures of cocrystallized yttrium europium propionates from 600 to 1000°C. [Copyright &y& Elsevier]

Abstract: The perovskite single-crystalline LaMnO3 nanocubes have been fabricated through a facile salt-assisted solution combustion process, using ethylene glycol as a fuel and corresponding nitrates as oxidants. The effects of the fuel-to-oxidant molar ratio and the fraction of added NaCl on the phase and microstructure of the products were investigated by X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The possible mechanism about the effect of molten salt on morphological evolution of the as-prepared LaMnO3 particles in salt-assisted solution combustion synthesis was also discussed. [Copyright &y& Elsevier]

Two-dimensional (2D) Co 3 O 4 thin sheets assembled by 3D interconnected nanoflake array framework structures were first synthesized from nanoflake array-assembled porous cobalt-oxalate coordination complex thin sheets by means of direct pyrolysis in the air and the synthesis is simple and facile to implement scale-up for various application. The products exhibit excellent pseudocapacitive performance in an alkaline medium, holding great promise in supercapacitors (SCs). The electrochemical properties of the obtained Co 3 O 4 thin sheets were evaluated by cyclic voltammetry (CV), galvanostatic charge–discharge measurement (CP) and electrochemical impedance spectroscopy (EIS) in 2.0 M KOH solution. Temperature has an obvious effect on the performance of the products. Impressively, the thin sheets synthesized at 500 °C for 6 h used as electrode materials for SCs exhibit a specific capacitance as high as 1500 F g −1 at 1 A g −1 and even 828 F g −1 at 10 A g −1 , as well as remarkable cycling stability with 99.3% of its initial capacitance retained after 2000 continuous charge–discharge cycles at a current density of 5 A g −1 . In addition, the assembled asymmetric system using the obtained Co 3 O 4 thin sheets at 500 °C for 6 h as positive electrode and activated carbon as negative one can produce a high energy density of 15.4 Wh kg −1 at a power density of 0.8 kW kg −1 . The hierarchical architectures of the products with hierarchical porosity and interconnected channels as well as the synergistic effect between their compositions provide several advantages including a large contact surface area, short ion diffusion path and good charge transport, which validate these thin sheets promising potential for a wide range of applications in energy storage. [ABSTRACT FROM AUTHOR]