Biocompatible superhydrophobic surface on Zr-based bulk metallic glass: Fabrication,characterization, and biocompatibility investigations

Superhydrophobic metal materials are promising candidates for preparing the precision blood-contacting medical devices. Finding a metal material with excellent biocompatibility and superplastic forming ability to fabricate superhydrophobic surface is of great practical significance. Zr-based bulk metallic glass with high glass-forming ability was selected as the experimental sample. Micro-nano hierarchical structure was etched by electrochemical method in the ultrasonic environment, and the superhydrophobic surface with good biocompatibility was obtained after further modification. Electrochemical polarization tests show that the superhydrophobic surface can maintain long-term corrosion resistance in simulated body fluids. Blood and cell tests indicate that the superhydrophobic sample has an extremely rate of hemolysis and exhibits the ability to effectively inhibit the adhesion of platelets and smooth muscle cells. In addition, the superhydrophobic sample surface also exhibits good mechanical durability and chemical stability. This study offers a new perspective on the application of Zr-based bulk metallic glass in blood-contacting medical devices.     

Hollow porous magnetic/magnetic heterostructured CoFe/defective spinel microspheres template-free synthesis and effective modulation of microwave absorption performance

To create a spinel ferrite with excellent performance for electromagnetic (EM) wave absorption in the low frequency range of 4–6 GHz, compositions based on Co_0.75Zn_0.125Fe_0.125Fe₂O₄ (CZF–1) and Co_0.5Zn_0.25Fe_0.25Fe₂O₄ (CZF–2) with multiple elements substituted for A sites were synthesized by using solvothermal method. Hollow porous magnetic/magnetic heterostructure microspheres (HHMs) of CZF–A1 and CZF–A2 with multiple interfaces were prepared by hydrogen–thermal reduction of CZF–1 and CZF–2, and their unique structure and EM absorption properties were investigated in detail. The widest effective absorption bandwidth (EAB) of CZF–A1 and CZF–A2 was 4.1 GHz (13.6–17.7 GHz) and 3.7 GHz (8.0–11.7 GHz) for a corresponding thickness of 1.4 mm and 2.0 mm, respectively. In addition, the minimum reflection loss (R.L_min) of CZF–A1 and CZF–A2 reached –49.1 dB (at f_m = 13.4 GHz) and –45.0 dB (at f_m = 4.2 GHz) at a thicknesses of 1.6 mm and 3.7 mm, respectively. More specifically, in the low frequency region of 4–6 GHz, CZF–A1 and CZF–A2 exhibited excellent EM wave absorption due to the effective regulation of their natural resonance frequency. The EM wave absorption frequency band of CZF–A1 and CZF–A2 samples was able to completely cover the 4–6 GHz frequency region for at coating thickness of CZF–A1 and CZF–A2 was only 3.5 mm and 3.3 mm respectively, and their R.Lmin reached –36.5 dB and –22.6 dB. Moreover, the absorption mechanisms of CZF–A1 and CZF–A2 including magnetic resonance, eddy current loss, interfacial polarization and dipole polarization were also investigated in detail. This research provides new insights and guidance for the development of spinel ferrite-based EM absorbers for high efficiency EM wave absorption in the low frequency (4–6 GHz) region.     

Recent advances in artificial neural network research for modeling hydrogen production processes

Artificial Neural Networks (ANN) have been widely used by scientists in a variety of energy modes (biomass, wind, solar, geothermal, and hydroelectric). This review highlights the assistance of ANN for researchers in the quest for discovering more advanced materials/processes for efficient hydrogen production (HP). The review is divided into two parts in this context. The first section briefly mentions, in terms of technologies, economy, energy consumption, and costs symmetrically outlined the advantages and disadvantages of various HP routes such as fossil fuel/biomass conversion, water electrolysis, microbial fermentation, and photocatalysis. Subsequently, ANN and ANN hybrid studies implemented in HP research were evaluated. Finally, statistics of hybrid studies with ANN are given, and future research proposals and hot research topics are briefly discussed. This research, which touches upon the types of ANNs applied to HP methods and their comparison with other modeling techniques, has an essential place in its field.     

A promising Bi-doped La0.8Sr0.2Ni0.2Fe0.8O3-δ oxygen electrode for reversible solid oxide cells

Reversible solid oxide cells (RSOCs) are clean and effective electrochemical conversion devices that require highly active electrodes and stable electrochemical performance for the practical application. Herein, we investigate a series of La_0.8-xBi_xSr_0.2Ni_0.2Fe_0.8O_3-δ (LBSNF-x, x = 0.0, 0.05, 0.1, 0.15) oxides as the potential oxygen electrode material for RSOCs. The properties of electrical conductivity, thermal expansion coefficient, and chemical compatibility with the Ce_0.9Gd_0.1O_1.95 (GDC) barrier layer of LBSNF-x oxides are evaluated. When LBSNF-0.1 and GDC forms a composite oxygen electrode with the ratio of 7:3, it shows the lowest polarization resistance with fastest oxygen reduction reaction activity in the symmetrical cell test. Then the cell with the configuration of Ni-YSZ/YSZ/GDC/LBSNF-0.1-GDC was prepared and evaluated both in fuel cell (FC) and electrolysis cell (EC) mode. The maximum power density of 824 mW cm⁻² is obtained at 800 °C in FC mode, and current density of 1.20 A cm⁻² is achieved under 50% steam content at 1.3 V in EC mode. Additionally, the cell exhibits good stability both in FC and EC mode after 80 h test at 700 °C. The results of this work provide a strong support for application of the LBSNF-0.1-GDC oxygen electrode for reversible solid oxide cells.     

Enhancement of the cathode/electrolyte interface by a sintering-active barrier layer for solid oxide fuel cells

It's a critical issue for the successful commercialization of solid oxide fuel cells (SOFCs) to achieve long-term operation and thermal cycling stability without significant degradation. Current work reports an almost-dense, sintering-active and Sr-blocking cathode/electrolyte interface, fabricated through a cost-competitive and scalable method of modifying porous Gadolinia doped Ceria (GDC) barrier layer by in-situ grown GDC nanoparticles. Result show that the robust interface enables improved durability and thermal cycling stability. The hydrothermal modified anode supported cell performance only deteriorates by ∼0.5% after 20 times thermal cycles between 200 and 750 °C, which is more prominent enhancement than ∼16% for pristine cell. The modified symmetric cell shows smaller cathode polarization resistance and well-attached cathode/electrolyte interfaces after ∼1200 h of operation, including 4 times thermal cycles. While the pristine cell shows more obvious area specific resistances increases and the peeled-off cathode layer. It is discussed and concluded that the hydrothermal modified sintering-active barrier layer has contributed mainly to the construction of robust cathode/electrolyte interface, yielding the improved performance and prolonged operation.     

System analysis of a protonic ceramic fuel cell and gas turbine hybrid system with methanol reformer

The performance of a methanol-fed protonic ceramic fuel cell (PCFC)/gas turbine (GT) hybrid system is investigated in this work. To build the system, Thermolib software is employed with input parameters obtained from references. Effects of air stoichiometry on system performance are analyzed. Results show that, as air stoichiometry is increased, the reformer temperature and CO concentration decrease, while H₂ concentration increases. High air stoichiometry decreases PCFC temperature and performance. GT output power increases with increasing air flow. But, the power consumption by compressor also increases. Overall, to achieve higher system efficiency for this hybrid system, the optimum values of air stoichiometry are from 2.7 to 2.9. An additional heat recovery steam generator can also improve the overall system efficiency from 66.5% to 71.7%. This work helps in understanding the modeling and optimum functioning parameters of high power generation systems.     

Densification and high-temperature oxidation behavior of SiC sintered with multicomponent rare-earth additives

This study examined the effects of rare-earth (RE) elements such as Sc, Y, Ce, and Yb on the densification and oxidation of SiC. After adding binary or ternary RE nitrates in liquid form to β-SiC, hot pressing was performed at 1750 °C for 2 h under 20 MPa. RE nitrate was transformed into RE oxide and formed a liquid phase during sintering by a reaction with SiO₂ present on the SiC surface, where the total amount of RE oxide was fixed at 5 wt%. RE-based silicate melts acted as sintering additives without decomposing SiC at high sintering temperatures. SiC containing Sc–Y as an additive showed a much higher density (≥ 99%) than SiC containing the conventional Al–Y additive (∼95%). The multicomponent RE additive with a melting point (T_m) < 1550 °C had a relatively lower density than that with a higher T_m, owing to the evaporation of the additive at 1750 °C. The density of SiC also depended on the additive composition. The oxidation test, conducted at 1300 °C for up to 168 h in air, exhibited a parabolic weight gain. The SiC sample sintered with the Sc–Yb additive achieved the highest resistance of 3.23 × 10⁻⁵ mg/cm⁴·s.     

Effects of ultrasonic vibration assisted milling with laser ablation pretreatment on fatigue performance and machining efficiency of SiCf/SiC composites

Due to the poor machinability of SiC_f/SiC parts in machining, many problems are caused, such as low machining efficiency, poor machining quality and high processing cost, which seriously limit its manufacturing and application. A novel process ultrasonic vibration assisted milling with laser ablation pretreatment (UVAMLAP) was proposed to optimize the fatigue performance and machining efficiency of SiC_f/SiC parts. This process was used to fabricate specimens, which were then tested for tensile strength and fatigue performance. The results show that UVAMLAP could enhance surface quality, and increase the tensile strength and residual tensile strength of the sample by 9.4% and 13.5%. This process can avoid damage aggravation in the initial stage of failure, weaken matrix fracture and interface debonding velocity, and reduce fatigue performance degradation caused by machining damage. In addition, comprehensive evaluation based on multi-dimensional indicators such as milling quality, machining efficiency and tool cost for machining strategy was carried out by taking tensile sample machining as an example. The UVAMLAP process can not only improve the machined surface quality, but also reduce the machining time by 31.3% and the tool cost by 75%. Therefore, UVAMLAP provides a feasible process scheme for high-efficiency and low-damage machining of SiC_f/SiC parts.     

Eco-driving policy for connected and automated fuel cell hybrid vehicles platoon in dynamic traffic scenarios

Cooperation of platooning vehicles enabled by eco-driving and connected and automated technology has shown considerable potential in energy saving and traffic efficiency improvement. However, affected by the impacts of the randomly changed states of traffic vehicles and the uncertainty of future road conditions, the adoption of eco-driving for the connected and automated fuel cell vehicle (CAFCHV) platoon in a dynamic traffic environment will encounter significant challenges. Additionally, improper inter-vehicle spacing can significantly affect operating safety and energy efficiency. To address this problem, a centralized variable spacing control strategy that adaptively adjusts with velocity and slope for the CAFCHV platoon is designed to calculate the optimal speed and promote energy allocation efficiency. In the upper control layer, gradient-based model prediction control (GRAMPC) is leveraged to calculate the optimal speed of the platoon, where the velocity of each vehicle can be regulated via its own and the surrounding vehicle's state and relative position. In the bottom layer, each vehicle in the platoon solves an MPC-based energy management strategy (EMS) to achieve power allocation in various power sources. Compared with the adaptive cruise control (ACC) driving manner, the simulation results regulated by the Planning manner display a considerable improvement in terms of the global cost, hydrogen consumption, battery degradation, and SOC by 1.36%, 1.48%, 2.47%, and 1.56%, respectively.