This study investigates the influence of different manufacturing routes on the corrosion behaviour of the Ti-25Nb-4Ta-8Sn beta titanium alloy produced by casting, powder metallurgy, and additive manufacturing using selective laser melting. The objective is to elucidate the relationship between microstructure and corrosion resistance in environments relevant to biomedical and dental applications, including simulated body fluids and fluoride-containing solutions. The selectively laser melted samples were intentionally fabricated using processing parameters chosen to promote increased porosity and defect formation to simulate a worst‑case scenario; these features are not inherent to optimised SLM Ti‑25Nb‑4Ta‑8Sn alloys. Consequently, the additively manufactured samples exhibited characteristic microstructural features such as melt pools, partially fused particles, crevices, and interconnected porosity, which influenced their corrosion behaviour. Corrosion performance was evaluated using electrochemical techniques, including open circuit potential measurements, potentiodynamic polarisation, and electrochemical impedance spectroscopy. The selectively laser melted alloy showed higher susceptibility to localised corrosion in neutral environments; however, under aggressive fluoride-containing conditions, it exhibited improved corrosion resistance due to the formation of a more stable and protective passive layer. The corrosion current density in fluoride media was approximately 20 µA/cm2 for cast alloy and 2 µA/cm2 for printed material. In contrast, the cast and powder metallurgy samples displayed comparable corrosion resistance, with only minor differences under aggressive conditions. The novelty of this work lies in the systematic comparison of corrosion mechanisms across multiple fabrication routes, explicitly accounting for defect-promoting additive manufacturing conditions relevant to realistic biomedical service environments.
Addressing the global challenge of climate change necessitates the development of innovative technologies for efficient gas separation, particularly for CO2 capture. Mixed matrix membranes (MMMs) offer a promising solution by synergically integrating the CO2-selective Pebax (R) 1657 with the intrinsic properties of metal-organic frameworks such as UiO-66. Herein, we focus on synthesizing, fabricating, and characterizing Pebax (R) 1657based MMMs with 0 (neat polymer), 5, 10, 15, and 20 wt% of composite magnetic nanoparticles (MNPs) derived from amine-functionalized UiO-66 and Mn-Fe oxide nanoparticles. An external magnetic field applied during membrane casting enabled the controlled embedding of MNPs. Material properties were analyzed using FTIR, SEM, XRD, EDX, TGA, BET, and surface roughness measurements. Gas permeation tests demonstrated that controlled embedding significantly improved additive distribution and membrane homogeneity, enhancing both gas permeability and selectivity compared to the neat polymer and MMMs with randomly embedded fillers. CO2 permeability increased from 71.5 (neat) to 245 Barrer (20 wt% of MNPs), with selectivity rising from 43.6 to 73.3 for CO2/N2 and from 18.2 to 21.0 for CO2/CH4. For O2/N2, permeability increased from 3.30 to 26.8 Barrer and selectivity from 2.0 to 6.4. SEM revealed well-ordered, chain-like MNP arrays in aligned membranes, while XRD showed preferred orientation of diffraction planes. These structural features were absent in neat Pebax and nonaligned variants, confirming the effect of magnetic alignment on filler organization. This study highlights the efficiency of controlled embedding as a strategy for enhancing Pebax (R) 1657-based MMMs for advanced gas separation.
Abstract With the occurrence of terrorist incidents and the intensification of war situations, concerns about biological and chemical warfare agents (BCWAs) created by mankind are growing due to their chilling characteristics such as high toxicity, high fatality rate, mass destruction, imperceptibility to senses, rapid dissemination, and even easy availability. In most cases, even slight exposure to these BCWAs can be a disaster because of their lethal or incapacitating effects on humans. Hence, it is urgently demanding to develop effective methodologies for sensitive detection and efficient neutralization of BCWAs in a specific scenario. Among various techniques, micro/nanorobots (MNRs), which can transfer energy from surroundings into kinetic energy for self‐propelled or field‐powered movement, have emerged as state‐of‐the‐art tools to actively combat biological and chemical threats. In this review, the latest research progress in MNRs for sensing and detoxification of BCWAs is presented. Toxins and pathogenic bacteria have been selected as the representatives for biological warfare agents, whereas nerve agents were chosen as typical chemical warfare agents. Besides, the working principles of MNRs based on their locomotion features (e.g., velocity changes) and constructed material characteristics (e.g., fluorescent on/off switch, photocatalytic effect, adsorption, and antibody‐antigen recognition) in terms of sensing and detoxification are summarized. Finally, current challenges and future perspectives for the development of fuel‐powered and field‐driven MNRs and their application in sensing and removing BCWAs are discussed.
Two-dimensional (2D) layered magnetic materials (LMMs) are a newly emerging class of van der Waals materials, opening new opportunities to study magneto-excitonic coupling. The air-stable, structurally and optically anisotropic A-type antiferromagnetic chromium sulfur bromide (CrSBr) is one of the most prominent examples of such LMMs. We investigate photoluminescence (PL) and PL excitation of mono- to tri-layers CrSBr and find that it exhibits a unique duplexity, supporting both Frenkel- and Wannier-Mott-like excitons. Our magneto-optical experiments reveal a similar excitonic response from the mono- and trilayer systems and a completely different signature in the bilayer flake. This shows a different origin of the low-lying excitonic species (A, A ' and B) in the band structure. We confirm the robustness of the magneto-excitonic coupling in few-layer CrSBr. Our work enables a more comprehensive exploration of the dual excitonic behavior in 2D materials.
We report the surface modification of biomass-derived porous carbon (PC) electrode with polyaniline (PANI) for supercapacitor (SC) and zinc-ion hybrid supercapacitor (ZIHSC) applications. This work includes the synthesis of PC from the Platanus orientalis bark using KOH as the activated agent in different weight ratios. Further, the electrochemical performance of fabricated PC based electrode was improved by electrochemical deposition of PANI over it at different potentials (1 V, 1.2 V and 1.5 V) and times (5 min, 10 min and 12 min). We found that 1.2 V and 12 min were optimal conditions for PANI deposition, with respect to better electrochemical output of the PC/PANI electrode. Symmetric SC (SSC) featuring this electrode exhibited the gravimetric capacitance (Cg) of 313.6 F/g at 0.5 A/g with an energy density of 62.7 Wh/kg. The ZIHSC exhibited a Cg of 422.6 F/g and an energy density of 284.1 Wh/kg at a current density of 0.5 A/g with a wide potential working voltage of 2.2 V. The modified electrode exhibits promising results for energy storage devices, which indicates that this approach could be beneficial for solving energy storage problems in the near future.
