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As a typical spinel structure material, ZnMn2O4 has been widely researched in the field of electrode materials. However, ZnMn2O4 nanoparticles as electrode materials for supercapacitors have the disadvantages of low conductivity, inferior structural integrity, and easy aggregation, resulting in unsatisfying electrochemical performance. In this work, we use a hydrothermal method and high-temperature calcination to deposit ZnMn2O4 nanoparticles on carbon cloth and explore the influence of hydrothermal reaction time on the deposition morphology and distribution of ZnMn2O4 nanoparticles on carbon cloth. The deposition process of ZnMn2O4 nanoparticles on carbon cloth was analyzed, and a ZMO-9 electrode was deduced to be the most suitable electrode for supercapacitors. A series of electrochemical performance tests show that the ZMO-9 electrode has excellent specific capacitance (specific capacity) (499 F·g−1 (299.4 C·g−1) at a current density of 1 A·g−1) and rate performance (75% capacitance retention at a current density of 12 A·g−1). The assembled asymmetric supercapacitor has an energy density of 46.6 Wh·kg−1 when the power density is 800.1 W·kg−1. This work provides a reference for the structural design of ZnMn2O4 supercapacitor electrode materials and the improvement of electrochemical properties. [ABSTRACT FROM AUTHOR]

The present paper reported a novel bipolar-pulse cathodic plasma electrolytic deposition (BP-CPED) technique with a low current density. This newly developed CPED technique can break down the barriers of the existing CPED technique with higher current density. In this report, ceramic coatings were successfully prepared on aluminum alloy via the BP-CPED technique in an aqueous carbamide-based electrolyte. Data recording results in the reacting process show that there is the current density of the cathode below 0.15 A/cm2 and that of the anode below 0.035 A/cm2, which approximately reaches the level of conventional MAO technique. Interestingly, the addition of PEG into the electrolyte can further reduce the current density and effectively improve the coating quality. The kinetic of the BP-CPED process was discussed based on the evolution of current density/voltage-time curves and spark discharge phenomena. SEM observations illustrate that BP-CPED coatings possess a typical porous-surface feature. XRD analysis indicates that the coating was mainly composed of Al2O3 and Al4C3. Al2O3/Al4C3/ZrO2 composite coatings fabricated after Zr-doping reflected the successful Zr-incorporation into the coating, which demonstrated that the BP-CPED technique can be used to design the coating composition by the doping modification. The direct pull-off and thermal shock tests confirmed that new BP-CPED coatings obtained under the cathodic plasma discharge have excellent bonding strength. It is possible that this novel BP-CPED technique can provide a promising choice in developing the large-area CPED surface treatment for the industrial application. [ABSTRACT FROM AUTHOR]

In response to the increasing threat of powerful earth-penetrating weapons, underground protective structures typically employ composite structural systems with reinforced steel layers. However, current numerical studies often simplify the entire structural system to plain concrete when assessing damage effects, and penetration and blasting processes are treated separately using a restart method. In this paper, we adopt an integrated simulation approach to analyze the resistance performance of composite protective structures with reinforcement layers. The results reveal significant differences in failure modes between plain concrete and reinforced concrete protective structures. The diameter of the steel bars and the spacing between mesh layers notably impact the penetration and blasting damage. Based on the results of a parameter analysis, we propose a method for optimizing the design of reinforcements in composite underground protective structures. The results of the study show the following: (1) The penetration and blast damage patterns of EPWs on plain concrete and composite protective structures with reinforcing mesh are significantly different. Compared to the plain concrete layer, the composite protection structure can effectively resist the damage of EPWs. (2) With the increase in reinforcement diameter, the decrease in reinforcement mesh spacing, and the increase in reinforcement dosage, the penetration depth gradually decreases; the amount and range of the blast damage also decrease accordingly. (3) Under the condition of the same reinforcement ratio, reducing the number of layers of reinforcement mesh, increasing the diameter of reinforcement, and configuring the reinforcement on the top of the protective structure as much as possible can improve the performance of the protective layer against penetration. At the same time, the reasonable arrangement of the reinforcement mesh can also enhance the ability of the protective structure to resist blasting damage. [ABSTRACT FROM AUTHOR]

A pulse-like ground motion identification method is proposed based on the Siamese Convolutional Neural Networks (SCNNs). The wavelet coefficient graphs of pulse-like ground motions are used as the input data, and the features extracted by the SCNNs are used for the identification. Based on the time-domain features, pulse-like and non-pulse-like ground motions are classified into several classes. The results indicated that all the identified pulse-like ground motions have similar pulse features to the pre-selected training data. The principal advantage of the method is that the misclassification problem can be minimized by an updating procedure proposed by this paper. [ABSTRACT FROM AUTHOR]

This paper develops the probabilistic seismic demand models of circular tunnels under the transversal seismic load. The uncertainties of ground motion, soil profile, tunnel depth, and lining size are considered. Since the quasi-static analyses may significantly underestimate the seismic responses of tunnels, the results of dynamic numerical analyses are adopted to construct probabilistic models that are more accurate. The constructed model is unbiased and can facilitate the fragility analysis of tunnels. As a demonstration, the proposed probabilistic models are used to estimate the seismic fragility curves of a particular tunnel. [ABSTRACT FROM AUTHOR]

This paper presents a numerical approach to construct the seismic probabilistic capacity models for the transversal lining section of circular tunnels. The influence of the lining dimension, reinforcement ratio, and properties of the concrete, reinforcement steel, and soil are considered. Two capacity measures, the bending moment M and the diametric distortion Δd/d, are considered, and each of them is represented by a separate model. To consider the possible correlation of the two capacity measures, a bivariate moment-distortion capacity model is also proposed. As an application example, the proposed capacity models are used to estimate the fragility curves of a tunnel. [ABSTRACT FROM AUTHOR]

Background: Increasing evidence has supported a link between obstructive sleep apnea (OSA) and cognition, and blood-brain barrier (BBB) dysfunction which can be reflected by paroxysmal slow wave events (PSWEs) may be a potential mechanism. The purpose of our study was to investigate the correlation between the PSWEs and cognitive impairment in patients with OSA, with a focus on the possible mechanism. Methods: In total, 339 subjects with subjective snoring complaints from the Sleep Medicine Center underwent magnetic resonance imaging and whole-night polysomnography. OSA was defined as apnea-hypopnea index (AHI) ≥ 5 events/h. MCI was defined as the MoCA < 26 and met the criteria: (1) subjective cognitive impairment; (2) objective impairment in one or more cognitive domains; (3) slightly impaired complex instrumental daily abilities, but independent daily living abilities; and (4) no dementia. The PSWEs calculated by self-developed Python scripts were defined for EEG recordings as a median power frequency of < 6 Hz for more than five consecutive seconds. Serum cyclophilin A (CyPA) and matrix metalloproteinase-9 (MMP-9) levels and amyloid-β 42 levels in neuron-derived exosomes were determined. The participants who received continuous positive airway pressure (CPAP) were followed up and their PSWEs were recalculated after 1 year of treatment. Results: A total of 339 participants were divided into the OSA+MCI group (n = 157), OSA-MCI group (n = 118), and controls (normal cognitive state without OSA) (n = 64). The total PSWEs and the occurrence per minute of PSWEs at stage REM in the OSA+MCI group were higher than those in the OSA-MCI and control groups. The duration ratio of PSWEs at stage REM in the OSA+MCI group significantly increased. The total PSWEs and PSWEs at the F4-M1, O1-M2, and O2-M1 channels in stage REM were independently associated with cognitive impairment in OSA patients. There were positive correlations between the PSWEs and serum CyPA and MMP-9 levels in patients with OSA. The mediation analysis showed that the relationship between mean SaO2 and percentage of sleep time spent with oxygen saturation <90% with MoCA scores was mediated by the total PSWEs (proportion of mediation 77.89% and 82.89%). The PSWEs were negatively correlated with global cognitive performance and cognitive subdomains. After 1 year of CPAP treatment, the total PSWEs, PSWEs in stage REM, and serum CyPA and MMP-9 levels decreased significantly, and MoCA scores were improved compared with baseline. Conclusions: The PSWEs were implicated in cognitive impairment in patients with OSA, and the mechanisms of cognitive impairment due to hypoxia in OSA patients could be BBB dysfunction. The PSWEs can be used as a marker of cognitive impairment in patients with OSA. Trial registration: This trial is registered on the Chinese Clinical Trial Registry, number ChiCTR1900021544. The trial was registered on February 27, 2019. [ABSTRACT FROM AUTHOR]

For large LNG storage tanks, the thermal load has a very important influence on the failure mode of the thin-walled spherical dome. However, the traditional calculation of thermal stress is very complicated for the spherical shell. To obtain an analytic solution with a simple expression, an approximate method was proposed in this paper. The mechanical behaviour caused by the temperature difference is divided into two parts, i.e. the thermal strain directly acting on the shell and the binding force exerted by the boundary. The thickness is ignored in the calculation of deflection caused by boundary constraints. Then, its accuracy was verified by a linear elastic numerical model. Furthermore, the crack pattern in a nonlinear plastic simulation was also well captured. The case study shows that the thermal-induced meridional cracks distribute uniformly along the circumferential direction; these cracks first appeared on the inner surface at the edge of the tank dome, and then rapidly expand to the centre and outer surface; increasing the amount of reinforcement cannot effectively limit the development of such cracks. [ABSTRACT FROM AUTHOR]

Considering the advantage of safety and cost, designing a Mg–air battery with high capacity has been highly sought in recent years. However, self-corrosion and passivation of Mg anode critically reduce discharge performance, hindering the large-scale application of Mg–air batteries. In this study, a series of as-cast and extruded Mg-3In-xCa alloys were successfully fabricated. Microstructures, chemical composition, and discharge performance were investigated to optimize the content of Ca (x). The selected Mg–air battery with Mg-3In-3Ca alloy as anode represented the best battery performance, including 0.738 V of discharge voltage, 1323.92 mAh g−1 of specific capacity, and 61.74% of anodic efficiency at discharge current density of 30 mA cm−2. All of its parameters were vastly superior to pure Mg–air battery. In addition, the synergistic effects of In and Ca on promoting electrode properties were evaluated in detail, using SEM and electrochemical analysis, which is expected to trigger follow-up research in designing high-performance Mg–air batteries. [ABSTRACT FROM AUTHOR]

Having a predominant pulse is the main feature for pulse-like ground motions differing from others. To investigate the influence of the predominant pulse on the inelastic displacement ratios of pulse-like ground motions, the wavelet analysis method is used to extract the predominant pulse. The results indicate that the inelastic displacement ratios of the pulse-removed parts obtained by subtracting the extracted pulse from the original pulse-like ground motions are close to the results of non-pulse-like ground motions. The ratio of the energy of the extracted pulse to the energy of the original ground motion is used to represent the pulse intensity. The results indicate that the pulse period determines the locations in which the inelastic displacement ratios would have noticeable increments, and the pulse intensity determines the degree of the increments. Besides, the effects of five commonly used parameters (PGV, PGD, PGV/PGA, Arias intensity Ia, and soil condition) on the inelastic displacement ratios of pulse-like ground motions and their relations to the pulse period and the pulse intensity are studied. Finally, a new model, in which the influence of pulse intensity is considered, to predict the inelastic displacement ratios of pulse-like ground motions is proposed. [ABSTRACT FROM AUTHOR]

A dual temperature-responsive triblock polymer (poly(N-isopropyl acrylamide)-block-poly(N,N-dimethyl acrylamide)-block-poly(acrylamide-co-acrylonitrile)) (P(AM-co-AN)-b-PDMA-b-PNIPAM) (NDAA) was obtained by sequential reversible addition–fragmentation chain transfer (RAFT) polymerization,with the uncharged UCST temperature-sensitive block P(AM-co-AN) and the classic LCST-type temperature-sensitive block PNIPAM. This well-defined thermo-responsive copolymer with tunable compositions exhibits a dual thermal response behavior in water. Properly designing the length of the block can make the block copolymer undergo a phase transition within the envisaged temperature range. When the concentration is 5 wt%, the UCST of the NDAA polymer is around 20 °C, and the LCST is around 31 °C. All three blocks of these polymers are soluble in water within 20–31 °C. At high temperature, PNIPAM hydrophobically aggregates into a core, and NDAA self-assembles into a core1 (PNIPAM)–shell (PDMA)–corona1 (P(AM-co-AN)) structure. In contrast, at low temperatures, P(AM-co-AN) forms hydrogen bonds and is insoluble in water, and NDAA self-assembles into a core2–shell–corona2 structure. In this way, it is possible to prepare spontaneously reversible micellar aggregates in water. After the concentration reaches the lowest critical concentration, the NDAA polymer can undergo a reversible gel behavior, that is, a phase transition occurs near the UCST and LCST. This change in the polarity of the micelle core opens up the possibility of dissolving different compounds in water just by changing the temperature. [ABSTRACT FROM AUTHOR]

A brand new pH and thermo-responsive amphiphilic ABC triblock copolymer of poly(acrylic acid)-block-poly(N,N-dimethyl acrylamide)-block-poly(acrylamide-co-acrylonitrile) (PAA-b-PDMA-b-P(AM-co-AN)) was synthesized via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization. Due to the pH-responsive blocks of PAA and thermo-responsive blocks of P(AM-co-AN), the properties of the copolymer solution were controlled by varying parameters such as temperature and pH. Specifically, it formed different nanostructures and showed gel behavior under different conditions. In detail, under high temperature alkaline conditions, ADAA was dissolved in an aqueous solution in the form of a molecular chain. Thereafter, when the temperature became lower or pH became acidic, the triblock copolymer self-assembled into different micelle structures, including shell–core, core–shell–core and tighter core–linking–core nanoparticles. In addition, the phase transition temperature of the copolymer was adjusted by pH and concentration. When the copolymer hydrogel was injected into a simulated human body device, it showed sustained drug release behavior and low transient drug concentrations. MTT experiments demonstrated the good biocompatibility of the ADAA hydrogels. This research provides inspiration to develop new polymers which are expected to be promising candidates as part of drug delivery platforms. Compared with traditional responsive hydrogels, its UCST can be easily controlled and is more stable through the feeding ratio, making it more advantageous in human drug delivery applications. In summary, we believe that this UCST and pH-responsive injectable ADAA hydrogel is researchable and applicable in the biomedical field. [ABSTRACT FROM AUTHOR]

In this study, a new percentage named "A value" was proposed, which was the key to evaluate whether solar thermal systems could be put into massive industrial application. A novel type of solar energy collector—black porcelain solar plate was developed. The solar absorptance of black coating was as high as 0.95 and did not decay against time. The performance of black porcelain solar roof systems (BPRSs) was investigated, which could be integrated with buildings and had the A value 2.49‐2.67 times higher than traditional solar thermal systems. The experimental results showed that the thermal efficiencies of BPRSs were more than 50%, which was about 20% higher than traditional solar thermal systems. BPRSs were widely known as low cost, long lifetime, no corrosion, and no aging. They could provide many applications for civil buildings, such as hot water of four seasons, summer air conditioning and winter heating. Once applied widely, solar energy collected by black porcelain solar plates might prospectively be the major source of human energy demand. [ABSTRACT FROM AUTHOR]

UV irradiation grafting technique was applied on a modified 316L stainless steel (SS) surface. The SS sheets were first coated with dopamine by dipping in the dopamine solution with KIO3 and ultrasonication. Then, the acrylamide (AAm) was grafted onto the dopamine-modified SS samples under UV irradiation with ultrasonication, when the ketone-diol compound was used as a photoinitiating system. For comparison, the UV irradiation grafting of AAm was also performed without ultrasonication. The structures and morphologies of the samples were examined by Fourier transform IR spectroscopy, atomic force microscopy, and scanning electronic microscopy before and after modification, respectively. Results showed that acrylamide was successfully grafted onto the poly-dopamine-coated SS. The hydrophilicity of the modified samples improved significantly, determined by the water contact angle measurement. Shown by Tafel polarization curves, the corrosion potential of modified SS was positively shifted, which demonstrated that the corrosion resistance was improved. [ABSTRACT FROM AUTHOR]

Appropriate estimates of earthquake response spectrum are essential for design of new structures, or seismic safety evaluation of existing structures. This paper presents an alternative procedure to construct design spectrum from a combined normalized response spectrum (NRS) which is obtained from pseudo-velocity spectrum with the ordinate scaled by different peak ground amplitudes (PGA, PGV, PGD) in different period regions. And a consecutive function f( T) used to normalize the ordinates is defined. Based on a comprehensive study of 220 strong ground motions recorded during recent eleven large worldwide earthquakes, the features of the NRS are discussed and compared with the traditional normalized acceleration, velocity and displacement response spectra (NRS, NRS, NRS). And the relationships between ground amplitudes are evaluated by using a weighted mean method instead of the arithmetic mean. Then the NRS is used to define the design spectrum with given peak ground amplitudes. At last, the smooth spectrum is compared with those derived by the former approaches, and the accuracy of the proposed spectrum is tested through an analysis of the dispersion of ground motion response spectra. [ABSTRACT FROM AUTHOR]

Corrosion—reactions occuring between engineering materials and their environment—can cause material failure and catastrophic accidents, which have a serious impact on economic development and social stability. Recently, super-hydrophobic coatings have received much attention due to their effectiveness in preventing engineering materials from further corrosion. In this paper, basic principles of wetting properties and corrosion protection mechanism of super-hydrophobic coatings are introduced firstly. Secondly, the fabrication methods by electrochemical surface engineering—including electrochemical anodization, micro-arc oxidation, electrochemical etching, and deposition—are presented. Finally, the stabilities and future directions of super-hydrophobic coatings are discussed in order to promote the movement of such coatings into real-world applications. The objective of this review is to bring a brief overview of the recent progress in the fabrication of super-hydrophobic coatings by electrochemical surface methods for corrosion protection of engineering materials. [ABSTRACT FROM AUTHOR]

Although super-hydrophobic surfaces have great application prospects in industry, their preparation cost and mechanical durability have limited their practical utilization. In this work, we presented a new low-cost process preparation for super-hydrophobic Co–Ni coating on carbon steel substrate via an electrodeposition route. The deposited Co–Ni coating with cauliflower-shaped micro-nano structures exhibited high super-hydrophobic properties with water contact angles over 161° after modification with 1H,1H,2H,2H-Perfluorooctyltrichlorosilane (PFTEOS). Evaluated by the linear abrasion methods, the super-hydrophobic coating can maintain super-hydrophobicity after abrasion distance of 12 m under the applied pressure of 5 kPa, which was attributed to the high cobalt content of the Co–Ni coating. Moreover, electrochemical tests showed that the super-hydrophobic Co–Ni coatings exhibited a good anti-corrosion performance thus providing an adequate protection to the carbon steel substrates. [ABSTRACT FROM AUTHOR]