Ningbo University of Technology

We propose and investigate an all-electrically controlled Josephson diode effect in a hybrid junction consisting of a quantum anomalous Hall insulator (QAHI) sandwiched between two topological superconductors (TSCs). Due to the spatial separation of two paired electrons from the chiral edge states, a transverse electric field applied across the two TSC leads imposes different energies on two paired electrons and modifies the spectrum of chiral Andreev bound states, consequently generating a sizable nonreciprocal supercurrent without the need for external magnetic fields. We further demonstrate two additional electrical control mechanisms: (i) tuning the chemical potential enhances the diode response by separating the superconducting gap from finite-size-induced gaps; and (ii) applying asymmetric electric fields to the two TSC leads enables precise and continuous modulation of the diode efficiency while preserving its polarity. The induced diode effect is shown to be robust against moderate disorders. Our results establish electrostatic gating as a powerful and practical approach to engineer and control nonreciprocal superconducting transport, providing a general framework for realizing electrically tunable topological Josephson diodes.

Ammonia (NH3) is a promising carbon-free fuel, but its practical application is limited by low reactivity. While oxygenated additives like dimethyl carbonate (DMC) are potential promoters, the kinetic interactions between DMC-derived intermediates and nitrogenous species remain poorly understood. This study investigates the laminar burning velocities (LBVs) and flame instabilities of DMC/NH3/air mixtures at 393 K and 1–4 atm, over equivalence ratios of 0.7–1.5 and NH3 mole fractions of 0–40%. A detailed kinetic model incorporating newly characterized CN kinetic interactions was developed through quantum chemistry calculations and validated against the present data.Results reveal that compared with the traditional alkane/NH3 system, a nonlinear inhibition effect exists in DMC/NH3 blends, deviating significantly from the ideal linear mixing rule. This non-additive behavior is influenced by a "NH2-to-NH3 recycling loop" in the preheat zone: the low-barrier reaction DMC+NH2 = CH3OCOOCH2+NH3 (E0​=8.24 kcal/mol) and CH2O+NH2 = NH3+HCO (E0 = 2.52 kcal/mol) competitively intercepts 42% of the NH2 flux at T = 900 K and 31.5% of the NH2 flux at T = 400 K, recycling it back to stable NH3. This pathway depletes the active radical pool available for the high-temperature flame front, and its omission leads to the overprediction of the global LBV. Furthermore, quantitative morphological analysis using spherical mapping reconstruction shows that NH3 addition enhances the intrinsic tendency toward cellular instability of short-chain oxygenates. While elevated pressure is the major physical driver, the synergistic chemical effect of NH3 advances the onset of cellularity from R ≈ 25 mm to a critical radius of R ≈ 15 mm, this chemical effect becomes less pronounced as pressure increases. Finally, cross-fuel comparison suggests a fuel-structure-dependent stability correlation: short-chain oxygenates (DMC, DME) are prone to NH3-induced destabilization, whereas long-chain analogues (PODE3, n-butanol) maintain robust stability. This work provides insights into the development of stable, low-emission combustion strategies for ammonia/oxygenated dual-fuel systems.

Abstract To study the seismic performance and shear strength capacity of flexure-shear critical RC bridge pier columns, including the corrosion effects of stirrups, low-cycle cyclic loading tests were conducted on nine circular pier columns with different corrosion levels of reinforcing bars (including the longitudinal bars and stirrups). The results showed that stirrup corrosion is more server than longitudinal bar corrosion in the pier columns under the same corrosion conditions due to the different protective effects of concrete protective layers with different thicknesses. The shear strength and deformation capacities of the pier columns are significantly reduced due to mechanical property degradation of corroded reinforcements as corrosion increases, and the columns are prone to evolve from ductile flexure failure to low-ductile flexure-shear failure. Compared with the uncorroded control column specimens, the peak lateral load and displacement ductility of the corroded specimens decreased by 16.79% and 34.78%, respectively, at approximately 20% theoretical stirrup corrosion ratio. In addition, the shear strength of flexure-shear critical corroded columns was defined to be distinct from that of shear critical corroded columns, and a novel model for estimating the shear strength capacity of flexure-shear critical columns with corroded stirrups was proposed.

Global shipping underpins international trade and constitutes a major source of greenhouse gas (GHG) emissions. As route security risks, trade frictions, and supply chain restructuring intensify, geopolitical disruptions are reshaping shipping activity and its emissions patterns. Based on high-frequency global Automatic Identification System (AIS) data for 2024, this study constructs a GHG emission inventory for global merchant vessels, and analyzes its spatial distribution, vessel-type emission composition, operational modes, and geopolitical variations. The results show that global merchant ships emitted 937.910 million tonnes of CO2e in 2024, exhibiting pronounced spatial clustering, with the North Atlantic, Mediterranean-Suez, Malacca Strait-South China Sea, and Trans-Pacific corridors forming the principal emission corridors. Container ships, oil tankers, and bulk carriers together accounted for 72.73% of total emissions; at sea operations accounted for 75.3%, berthing-mode emissions for 19.0%, and main-engine emissions for 70.2%. Geopolitical disruptions were associated with substantial and persistent spatial redistribution of shipping emissions in 2024. Emissions along the Red Sea and Suez routes sharply declined from January to March, while emissions along the Cape of Good Hope route increased. This opposing spatial pattern is consistent with route redistribution during the Red Sea crisis. Changes in emissions along the China-U.S. and China-Vietnam routes coincided with the escalation of U.S.-China trade tensions and reflect changes in regional trade and transshipment patterns. These findings highlight how geopolitical conditions can affect shipping decarbonization pathways and underscore the need to incorporate geopolitical risk resilience into emission reduction policies for achieving the IMO net-zero target.

This study develops high-performance shape-stabilized phase change materials (SSPCMs) by valorizing waste bamboo charcoal ash (BCA) and bamboo biochar (BB) as porous scaffolds. N-octadecane was encapsulated via vacuum infiltration, with expanded graphite (EG) added to enhance thermal conductivity. Characterization results reveal that BCA’s mesoporous structure (average pore diameter: 9.46 nm) enables a superior phase change material (PCM) loading of 55