ARC Centre of Excellence for Electromaterials Science

In cold-formed steel (CFS) connections, self-tapping screws have increasingly been used with pre-punched dimples to improve assembly accuracy and installation efficiency. However, the structural behaviour of such connections remains poorly understood, and current international design standards provide no specific guidance for their design. This paper presents an experimental investigation on single-lap screwed connections, both with and without dimples, to examine their shear behaviour, ultimate strength, and failure modes. The test matrix comprised four steel sheet thicknesses and various plate arrangements relative to the screw heads. The dimpled holes were automatically pre-punched with an indent depth of 1.5 mm and hole diameters ranging from 4.9 mm to 5.3 mm, accommodating 14g-20×14 mm screws with a nominal diameter of 6.3 mm. Non-dimpled specimens typically failed by screw tilting or a combination of tilting and bearing, whereas dimpled specimens predominantly failed in bearing. The presence of dimples improved resistance to screw tilting due to the interlocking mechanism developed at the connection interface. Measured shear resistances were compared with predictions from EN 1993-1-3:2006, ANSI/SDI AISI S100:2024, and AS/NZS 4600:2018. For bearing failures, current design equations provided relatively accurate predictions for non-dimpled connections; however, no design provisions exist for dimpled-hole connections. These findings highlight the need for new design rules that explicitly account for the influence of dimples, particularly under bearing failure. A companion paper presents new design equations for shear-loaded CFS screwed connections with dimpled holes, calibrated against the experimental results reported herein and validated through nonlinear finite element analyses in an extended parametric study. • A single-lap shear test configuration was developed to evaluate screwed connections with dimples. • Screwed connections with and without dimples were tested using four different steel sheet thicknesses. • Non-dimpled specimens typically failed by screw tilting or a combination of tilting and bearing. • Dimpled specimens exhibited improved resistance to screw tilting due to an interlocking mechanism. • No design provisions currently exist in standards for the design of screwed connections with dimples in shear.

Abstract Solid‐state hydrogen storage materials with optimal binding energy are essential for hydrogen storage and transportation applications and pose long‐standing challenges. Current technologies, including molecular physisorption materials (e.g., metal–organic frameworks (MOFs), carbon nanotubes (CNTs), activated carbons (ACs)) and atomic chemisorption materials (e.g., MgH2, LiBH4, NH4BH4), fall short of meeting practical application requirements. Therefore, designing and constructing new solid‐state hydrogen storage materials at the atomic level is critically important. In this study, the use of defect engineering is explored to modulate hydrogen adsorption sites on TiO2 surfaces. The results demonstrate that low‐coordinated titanium (Ti) atoms on TiO2 can serve as effective hydrogen adsorption sites, storing hydrogen through molecular chemisorption with significantly enhanced adsorption energy compared to Ti atoms in high coordination states. Moreover, the adsorbed hydrogen remains in molecular form, facilitating easy desorption at room temperature, unlike titanium hydride, which requires high temperatures for desorption. This approach provides a promising pathway for developing efficient hydrogen storage materials by leveraging the unique properties of low‐coordinated Ti atoms on TiO2 surfaces.

Polypyrrole (PPy) is cationic in its conducting form, requiring a charge-balancing counterion, or dopant. The release of bioactive dopants, driven by the reduction of PPy films, offers a route to controlled drug delivery. Thiol-terminated long chain poly (ethylene glycol) (PEG) reacts with a dodecylbenzene sulfonate (DBSA)-doped PPy, forming a dense overlayer and partially liberating DBSA via the chemical reduction of the film. The resulting PEG brush acts as a barrier to dopant diffusion from the film, but proteins have been shown to disrupt this layer, releasing the DBSA. The mechanism by which this disruption occurs has not been thoroughly investigated. In this study, dopant release from PEG-PPy composites was examined via systematic exposure to a variety of chemical stimuli, including macromolecules such as poly (ethylene imine), polyethylene glycol, and poloxamers, as well as small-molecular-weight alcohols, carboxylic acids, and amines. Dopant release was quantified by quartz crystal microbalance. Poly (ethylene imine) efficiently released DBSA, while anionic and uncharged macromolecules did not. All classes of small molecules triggered dopant release, with longer homologues magnifying the response. The mechanisms of dopant removal are dependent on the functional groups of the stimulating agent and include ion exchange and nucleophilic reduction of the polycationic backbone. Tosylate, salicylate, and penicillin dopants showed release behaviors similar to DBSA, demonstrating the generality of the PEG barrier.

Hard carbon is the most commercially viable anode material for sodium-ion batteries (SIBs), yet its application in ester-based electrolytes is hindered by sluggish interfacial ion diffusion and limited sodium nucleation kinetics. After comprehensive evaluation, an interfacial chemistry regulation strategy was proposed based on orbital hybridization between bismuth and electrolyte ions, which was realized through the introduction of ammonium bismuth citrate. The surface bismuth particles regulate the formation of a NaF-rich SEI through improved anion affinity. In collaboration with the in situ generated highly ion-conductive Na3N, a thin, compact and homogeneous SEI was constructed to enable fast and stable interfacial Na+ migration kinetics. Moreover, the Bi atoms can diffuse into the hard carbon structures, expanding the carbon interlayers to facilitate ion diffusion and intercalation as well as enhancing the sodiophilicity in closed pores to lower the nucleation barrier. Benefiting from these merits, the resulting T2-BiN exhibits superior sodium-storage kinetics with outstanding rate capability (185.6 mA h g-1 at 0.5 A g-1) and long-term cycling stability (84.4% after 400 cycles at 0.5 A g-1) in the ester-based electrolyte. Even the practical full cell showed no capacity decay over 400 cycles at 2C. This work provides a simple and effective interfacial modification strategy, offering new insights into the advancement of hard carbon anodes for high-performance SIBs.

Quick and easy prototyping methods are beneficial for accelerated product development, allowing for concepts to be realised through quick experimentation, validating predictions based on theory and modelling. A rapid subtractive method for the fabrication of metallic antennas, using laser ablation is reported here. These antennas may be designed for a wide range of wireless power reception applications, as integral parts of a powered device. In line with typical application in sub-dermal implants, we designed the antennas in this work to operate at distances similar to that of the dermis. Inductive spiral coil designs are fabricated from gold on a biocompatible soft polymer, Polydimethylsiloxane (PDMS). PDMS has low dielectric constant of 2.32-2.40 and low loss tangent of 0.04-0.06, which is advantageous for use as antenna substrate. The fabricated inductive coils on PDMS are characterized through electrical impedance spectroscopy and tested as a wireless signal receiver, coupled with a Qi standard wireless transmitting module, at an operating frequency of 100 kHz. Importantly, the fabricated coils show resonance in the operational frequency range of the Qi standard (100 kHz to 125 kHz). This is the first instance of laser ablation defined spiral antennas on biocompatible elastomeric substrates. Although the PDMS based inductive coils have high impedance of 2800 ± 300 Ω at 100 kHz, owing to the mechanical mismatch of rigid conductor and flexible substrate, this approach shows promise. Furthermore, strategies to decrease the impedance of such PDMS-based devices are also discussed.

Abstract Biomes are large‐scale ecosystems occupying large spaces. The biome concept should theoretically facilitate scientific synthesis of global‐scale studies of the past, present, and future biosphere. However, there is neither a consensus biome map nor universally accepted definition of terrestrial biomes, making joint interpretation and comparison of biome‐related studies difficult. “Desert,” “rainforest,” “tundra,” “grassland,” or “savanna,” while widely used terms in common language, have multiple definitions and no universally accepted spatial distribution. Fit‐for‐purpose classification schemes are necessary, so multiple biome‐mapping methods should for now co‐exist. In this review, we compare biome‐mapping methods, first conceptually, then quantitatively. To facilitate the description of the diversity of approaches, we group the extant diversity of past, present, and future global‐scale biome‐mapping methods into three main families that differ by the feature captured, the mapping technique, and the nature of observation used: (1) compilation biome maps from expert elicitation, (2) functional biome maps from vegetation physiognomy, and (3) simulated biome maps from vegetation modeling. We design a protocol to measure and quantify spatially the pairwise agreement between biome maps. We then illustrate the use of such a protocol with a real‐world application by investigating the potential ecological drivers of disagreement between four broadly used, modern global biome maps. In this example, we quantify that the strongest disagreement among biome maps generally occurs in landscapes altered by human activities and moderately covered by vegetation. Such disagreements are sources of bias when combining several biome classifications. When aiming to produce realistic biome maps, biases could be minimized by promoting schemes using observations rather than predictions, while simultaneously considering the effect of humans and other ecosystem engineers in the definition. Throughout this review, we provide comparison and decision tools to navigate the diversity of approaches to encourage a more effective use of the biome concept.

This study investigates the electrochemical behavior of GelMA-based hydrogels and their interactions with PC12 neural cells under electrical stimulation in the presence of conducting substrates. Focusing on indium tin oxide (ITO), platinum, and gold mylar substrates supporting conductive scaffolds composed of hydrogel, graphene oxide, and gold nanorods, we explored how the substrate materials affect scaffold conductivity and cell viability. We examined the impact of an optimized electrical stimulation protocol on the PC12 cell viability. According to our findings, substrate selection significantly influences conductive hydrogel behavior, affecting cell viability and proliferation as a result. In particular, the ITO substrates were found to provide the best support for cell viability with an average of at least three times higher metabolic activity compared to platinum and gold mylar substrates over a 7 day stimulation period. The study offers new insights into substrate selection as a platform for neural cell stimulation and underscores the critical role of substrate materials in optimizing the efficacy of neural interfaces for biomedical applications. In addition to extending existing work, this study provides a robust platform for future explorations aimed at tailoring the full potential of tissue-engineered neural interfaces.

Abstract Low Na+ and electron diffusion kinetics severely restrain the rate capability of MoS2 as anode for sodium‐ion batteries (SIBs). Slow phase transitions between 2H and 1T, and from NaxMoS2 to Mo and Na2S as well as the volume change during cycling, induce a poor cycling stability. Herein, an original Fe single atom doped MoS2 hollow multishelled structure (HoMS) is designed for the first time to address the above challenges. The Fe single atom in MoS2 promotes the electron transfer, companying with shortened charge diffusion path from unique HoMS, thereby achieving excellent rate capability. The strong adsorption with Na+ and self‐catalysis of Fe single atom facilitates the reversible conversion between 2H and 1T, and from NaxMoS2 to Mo and Na2S. Moreover, the buffering effect of HoMS on volume change during cycling improves the cyclic stability. Consequently, the Fe single atom doped MoS2 quadruple‐shelled sphere exhibits a high specific capacity of 213.3 mAh g−1 at an ultrahigh current density of 30 A g−1, which is superior to previously‐reported results. Even at 5 A g−1, 259.4 mAh g−1 (83.68 %) was reserved after 500 cycles. Such elaborate catalytic site decorated HoMS is also promising to realize other “fast‐charging” high‐energy‐density rechargeable batteries.