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In this study, we explore how the strategic positioning of conductive yarns influences the performance of plated knit strain sensors fabricated using commercial knitting machines with both conductive and non-conductive yarns. Our study reveals that sensors with conductive yarns located at the rear, referred to as ‘purl plated sensors’, exhibit superior performance in comparison to those with conductive yarns at the front, or ‘knit plated sensors’. Specifically, purl plated sensors demonstrate a higher sensitivity, evidenced by a gauge factor ranging from 3 to 18, and a minimized strain delay, indicated by a 1% strain in their electromechanical response. To elucidate the mechanisms behind these observations, we developed an equivalent circuit model. This model examines the role of contact resistance within varying yarn configurations on the sensors’ sensitivity, highlighting the critical influence of contact resistance in conductive yarns subjected to wale-wise stretching on sensor responsiveness. Furthermore, our findings illustrate that the purl plated sensors benefit from the vertical movement of non-conductive yarns, which promotes enhanced contact between adjacent conductive yarns, thereby improving both the stability and sensitivity of the sensors. The practicality of these sensors is confirmed through bending cycle tests with an in situ monitoring system, showcasing the purl plated sensors’ exceptional reproducibility, with a standard deviation of 0.015 across 1000 cycles, and their superior sensitivity, making them ideal for wearable devices designed for real-time joint movement monitoring. This research highlights the critical importance of conductive yarn placement in sensor efficacy, providing valuable guidance for crafting advanced textile-based strain sensors.

This paper investigates the effect of the size and volume fraction of SiC, along with that of the processing temperature, upon the nitridation behavior of aluminum powder during the nitridation-induced self-formed aluminum composite (NISFAC) process. In this new composite manufacturing process, aluminum powder and ceramic reinforcement mixtures are heated in nitrogen gas, thus allowing the exothermic nitridation reaction to partially melt the aluminum powder in order to assist the composite densification and improve the wetting between the aluminum and the ceramic. The formation of a sufficient amount of molten aluminum is key to producing sound, pore-free aluminum matrix composites (AMCs); hence, the degree of nitridation is a key factor. It was demonstrated that the degree of nitridation increases with decreasing SiC particle size and increasing SiC volume fraction, thus suggesting that the SiC surface may act as an effective pathway for nitrogen gas diffusion. Furthermore, it was found that effective nitridation occurs only at an optimal processing temperature. When the degree of nitridation is insufficient, molten Al is unable to fill the voids in the powder bed, leading to the formation of low-quality composites with high porosities. However, excessive nitridation is found to rapidly consume the nitrogen gas, leading to a rapid drop in the pressure in the crucible and exposing the remaining aluminum powder in the upper part of the powder bed. The nitridation behavior is not affected by these variables acting independently; therefore, a systematic study is needed in order to examine the concerted effect of these variables so as to determine the optimal conditions to produce AMCs with desirable properties for target applications.

We investigate the effects of the molar ratio (x) of PbBr2 on the phases, microstructure, surface morphology, optical properties, and structural defects of mixed lead halides PbI2(1−x)Br2x for use in solar cell devices. Results indicate that as x increased to 0.3, the surface morphology continued to improve, accompanied by the growth of PbI2 grains. This resulted in lead halide films with a very smooth and continuous morphology, including large grains when the film was formed at x = 0.3. In addition, the microstructure changed from (001)-oriented pure PbI2 to a highly (001)-oriented β (PbI2-rich) phase. The plausible mechanism for the enhanced morphology of the lead halide films by the addition of PbBr2 is proposed based on the growth of a Br-saturated lead iodide solid solution. Furthermore, iodine vacancies, identified by X-ray photoelectron spectroscopy, decreased as the ratio of PbBr2 increased. Finally, an electrical analysis of the solar cells was performed by using a PN heterojunction model, revealing that structural defects, such as iodine vacancies and grain boundaries, are the main contributors to the degradation of the performance of pure PbI2-based solar cells (including high leakage, low stability, and high hysteresis), which was significantly improved by the addition of PbBr2. The solar cell fabricated at x = 0.3 in air showed excellent stability and performance. The device lost merely 20% of the initial efficiency of 4.11% after 1500 h without encapsulation. This may be due to the dense microstructure and the reduced structural defects of lead halides formed at x = 0.3.

We introduce a novel method for fabricating perovskite solar modules using selective spin-coating on various Au/ITO patterned substrates. These patterns were engineered for two purposes: (1) to enhance selectivity of monolayers primarily self-assembling on the Au electrode, and (2) to enable seamless interconnection between cells through direct contact of the top electrode and the hydrophobic Au connection electrode. Utilizing SAMs-treated Au/ITO, we achieved sequential selective deposition of the electron transport layer (ETL) and the perovskite layer on the hydrophilic amino-terminated ITO, while the hole transport layer (HTL) was deposited on the hydrophobic CH3-terminated Au connection electrodes. Importantly, our approach had a negligible impact on the series resistance of the solar cells, as evidenced by the measured specific contact resistivity of the multilayers. A significant outcome was the production of a six-cell series-connected solar module with a notable average PCE of 8.32%, providing a viable alternative to the conventional laser scribing technique.

The nitridation-induced self-formed aluminum matrix composite (NISFAC) process is based on the nitridation reaction, which can be significantly influenced by the characteristics of the starting materials (e.g., the chemical composition of the aluminum powder and the type, size, and volume fraction of the ceramic reinforcement) and the processing variables (e.g., process temperature and time, and flow rate of nitrogen gas). Since these variables do not independently affect the nitridation behavior, a systematic study is necessary to examine the combined effect of these variables upon nitridation. In this second part of our two-part report, we examine the effect of nitrogen flow rates and processing temperatures upon the degree of nitridation which, in turn, determines the amount of exothermic reaction and the amount of molten Al in the nitridation-induced self-formed aluminum matrix composite (NISFAC) process. When either the nitrogen flow rate or the set temperature was too low, high-quality composites were not obtained because the level of nitridation was insufficient to fill the powder voids with molten Al. Hence, since the filling of the voids in the powder bed by molten Al is essential to the NISFAC process, the conditions should be optimized by manipulating the nitrogen flow rate and processing temperature.

With its well-known popularity in structural applications, considerable attention has recently been paid to iron (Fe) and its oxides for its promising functional applications such as biodegradable implants, water-splitting electrodes, and the anode of lithium-ion batteries. For these applications, iron and its oxides can be even further utilized in the form of porous structures. In order to control the pore size, shape, and amount, we synthesized Fe foams using suspensions of micrometric Fe2O3 powder reduced to Fe via freeze casting in water or liquid camphene as a solvent through sublimation of either ice or camphene under 5 pct H2/Ar gas and sintering. We then compared them and found that the resulting Fe foam using water as a solvent (p = 71.7 pct) showed aligned lamellar macropores replicating ice dendrite colonies, while Fe foam using camphene as a solvent (p = 68.0 pct) exhibited interconnected equiaxed macropores replicating camphene dendrites. For all directions with respect to the loading axis, the compressive behavior of the water-based Fe foam with a directional elongated wall pore structure was anisotropic (11.6 ± 0.9 MPa vs 7.8 ± 0.8 MPa), whereas that of the camphene-based Fe foam with a random round pore structure was nearly isotropic (12.0 ± 1.1 MPa vs 11.6 ± 0.4 MPa).

Computer-controlled optical surfacing provides superior optical fabrication performance with low-cost mass production over conventional method relying heavily on the skills of optician. However, there are still lots of technical issues to be resolved in computer-controlled optical surfacing, and edge effect has been regarded as one of the most challenging tasks for years due to the unpredictable behaviors of a polishing tool. As a polishing tool approaches the edge of the workpiece, the tool-workpiece contact area decreases and this in turn accompanies the tool-workpiece misfit and non-uniform pressure distribution. Thus, the edge effects should be taken into account in deterministic polishing technique. In this paper, we suggest new edge tool influence functions by modeling the velocity and pressure distribution of a polishing tool with eccentric rotation motion. Here, the finite element analysis was used to accurately predict the non-linear behaviors of a polishing tool at the edge. We verified our proposed method by comparisons with experimental results, and it shows considerable resemblance between them.

Known as a hard magnetic material, cobalt ferrite belongs to one of the most attractive classes of materials owing to its diverse technical applicability such as in catalysis, sensors, batteries. In this study, we synthesized Li- and Y-substituted cobalt ferrite nanoparticles using a sol–gel combustion method. Their mean crystallite sizes with spinel structures were calculated as 15–19 and 2–5 nm and their lattice constant values were 7.8 ± 0.02 and 8.5 ± 0.3 Å, respectively. The results also revealed that the band gap energy values of the prepared Li- and Y-doped cobalt ferrites decreased after doping compared with that of pure cobalt ferrite, and thus they appear to be promising for energy generation and storage applications.

Inspired by the controversy over tensile deformation modes of single-crystalline 〈110〉/{111} Au nanowires, we investigated the dependency of the deformation mode on diameters of nanowires using the molecular dynamics technique. A new criterion for assessing the preferred deformation mode-slip or twin propagation--of nanowires as a function of nanowire diameter is presented. The results demonstrate the size-dependent transition, from superplastic deformation mediated by twin propagation to the rupture by localized slips in deformed region as the nanowire diameter decreases. Moreover, the criterion was successfully applied to explain the superplastic deformation of Cu nanowires.

In this study, Ti foams with 80 to 85 pct porosity and 300 to 500 μm pore size were fabricated using a unique space holder method. Because of their large surface area originated from sufficiently small pore size (a few hundreds of micrometers), good mechanical properties, interconnected three-dimensional (3D) structure with high electrical conductivity, and sufficiently short diffusion distances for electrons, they were successfully demonstrated as a novel 3D structured current collector for a next-gen electric double layer capacitor (EDLC). An additional heat treatment was performed on the fabricated Ti foams to further improve their mechanical properties, thus sustaining their structure over a long operational lifetime and enabling higher porosity 3D metal foam structure (a higher amount of slurry filling and enhanced capacity). Compressive test revealed a noticeable increase in the yield strength of the Ti foam due to the heat-treatment. The gravimetric capacity of the Ti foam-based electric double-layer capacitors was estimated to be between 33 and 37 F/g at 0.025 A/g. Furthermore, the novel 3D Ti foam electrodes, when compared with the typical foil-type electrodes, exhibited considerably more efficient charging/discharging reactions, thus resulting in enhanced volumetric capacitance as compared to commercially available EDLCs.