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In this study, we employ first-principles density functional theory (DFT) to investigate the electronic, magnetic, and thermodynamic properties of niobium-decorated tungsten disulfide (Nb@WS2), a potential material for gas capture and sensing. The adsorption behavior of CO, HCHO, NO, and NO2 was systematically investigated. Adsorption energies (Eads) range from-1.481 eV (CO) to-3.290 eV (NO2), with NO2 exhibiting the strongest interaction due to the high difference in electronegativity between interacting N and Nb atoms. Partial density of states (PDOS), Bader charge analysis, electron density difference (EDD), and electron localization function (ELF) collectively reveal significant charge transfer from Nb@WS2 to gas molecules, confirming the chemisorption nature of the interactions and the emergence of distinct electronic and magnetic signatures. Work function analysis showed notable increases upon gas adsorption, correlating with sensitivity enhancements of up to 18.24 % for NO. However, the elevated Eads values observed in these systems, leading to their enormous recovery times, pose specific challenges for their practical use as reusable gas sensors. Moreover, ab initio molecular dynamics (AIMD) simulations at 500 K confirm the thermal stability of gas-adsorbed configurations, reinforcing the viability of Nb@WS2 for high-temperature sensing or capturing applications.
This paper explores the underexamined role of institutional fragility in shaping urban displacement across Sub-Saharan Africa (SSA), a region experiencing rapid urbanization amid persistent governance challenges. Drawing on a panel dataset of 38 SSA countries from 2000 to 2024, the study applies Difference-in-Differences (DID) and Quantile DID (QDID) methods to examine how political instability, public sector weakness, and legal fragility influence displacement trends. The results show that political instability measured through political violence, refugee outflows, and net migration is strongly associated with rising urban displacement. Importantly, this relationship is conditioned by resilience factors: countries with stronger electricity access and higher public health expenditure experience less severe displacement pressures. Public sector weakness captured by government effectiveness, expenditure, and regulatory quality also increases displacement risks, though these effects vary depending on how fiscal resources are directed toward service provision. Legal fragility indicators such as weak rule of law, corruption, and limited voice further exacerbate displacement where institutional protections and services are absent. The quantile analysis highlights that the most severe effects occur in already vulnerable urban contexts. Policy recommendations call for context-specific responses, including resilience-oriented infrastructure, targeted legal reforms, improved data systems, and more inclusive public spending. The findings provide new empirical insights into the institutional roots of Africa's urban displacement crisis and offer a framework for designing adaptive responses to future risks.
Fuel-cell vehicles (FCVs) offer compelling advantages for sustainable transportation, including rapid refueling, extended driving range, and zero CO2 emissions. However, the current reliance on highly pressurized hydrogen (H2) tanks presents significant challenges in terms of safety, operational pressure, and storage capacity. Moving beyond conventional compressed gas storage, this study explores a solid-state H2 storage paradigm based on light, nanoporous organic penta-carbon nitride (C5N) decorated with light transition metals (TMs). Using density functional theory (DFT), thermodynamic analysis, and ab-initio molecular dynamics (AIMD), we show that selected TMs, Sc, Ti, and V, can be energetically anchored onto C5N without clustering, owing to the synergy between their strong binding energies and high diffusion barriers. The TM-decorated C5N exhibit reversible H2 adsorption via peculiar Kubas-type interactions, achieving high theoretical gravimetric densities of 5.81, 5.73, and 5.65 wt% for Sc, Ti, and V@C5N, respectively. These numbers surpass the U.S. Department of Energy (DOE) target of 5.50 wt%. Notably, Sc@C5N and V@C5N also demonstrate the ability to store H2 under practical ranges of temperatures and pressures, with reversible adsorption at 5.0 bar and desorption at practically low temperatures (below 85.0 degrees C). Our findings conclusively propose TM-decorated C5N as highly promising candidates for H2 storage in FCVs.
Two-dimensional (2D) materials with a high surface-to-volume ratio and excellent electronic properties have been extensively used as hydrogen (H2) storage mediums. In this study, the first-principles calculations have been implemented to explore the structural, electronic and H2 storage performance of recently synthesized boron monoxide (BO) monolayer decorated with the scandium (Sc) dopants. It is found that doping with three Sc atoms, resulting in the formation of 3Sc@BO material, changes the electronic properties of BO from semiconducting to conducting. The Sc dopants are bonded with the BO in the form of Sc-O bonds with significantly strong binding energies of-4.628,-4.708 and-4.323 eV/Sc, for Sc@BO, 2Sc@BO, and 3Sc@BO, respectively. Thermal stability of the 3Sc@BO system is verified through ab initio molecular dynamics (AIMD) simulations. The H2 molecules adsorbed on 3Sc@BO are polarized and exhibit the obvious hybridization between H2 and Sc. Under maximum hydrogenation, the 3Sc@BO could adsorb to a maximum of 19H2 molecules, resulting in a high storage capacity of 10.96 wt%, and the average adsorption energy is-0.35 eV/H2. The adsorption of H2 on 3Sc@BO is elaborated as a synergistic collaborative amalgamation of physical and chemical adsorption mechanisms. Furthermore, relative energy analysis indicates that H2 molecules remain adsorbed on 3Sc@BO at 298.15 K and moderate pressures, and the desorption occurs at temperatures above 319 K. Our findings reveal the potential of 3Sc@BO as a high-capacity H2 storage material.
A digital twin (DT) is a real-time, highly accurate, virtual replica that reflects the states and behaviours of physical objects or systems. DTs can enable monitoring, simulation, prediction, optimisation as well as the structured integration of technologies, data flows and functional processes within smart industries. In recent years, the DT technology has emerged as a research hotspot, which has prompted us to conduct a review of its development and application in various industries. We have identified 30 leading journals that have significantly contributed to DT research, with the Computers in Industry (CII) journal ranking second among these 30 journals with more than 80 related publications. After briefly discussing the key concepts and major milestones around the development and rapid adoption of DTs in smart industries, we focus on reviewing and analysing the DT publications from the CII journal from 2018 to present by systematically categorising them into four primary application domains: manufacturing, construction, transportation, and technologies and paradigms. We also discuss potential research opportunities (e.g., life cycle management, cross-disciplinary integration, human-machine collaboration) and challenges from a theoretical perspective, and provide managerial insights (e.g., building open standards, enhancing data access compatibility, extending DTs’ operational functions, applications to more industries) from a practical perspective. This review will be helpful for academic researchers and industrial practitioners to gain a broad understanding of the versatility of DTs, thereby fostering interdisciplinary innovation.
