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In this article, the evolution of microstructural characteristics of selectively laser-melted AlSi10Mg alloy subjected to equal channel angular pressing (ECAP) is investigated. The microstructures were analyzed in detail using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), and transmission electron microscopy (TEM). A heterogeneous ultrafine-grained microstructure was produced after one ECAP pass at 100 °C. This microstructure was composed of Al/Si cells and sub-micrometer grains. The grains were refined by conventional dislocation processes; however, evidence of dynamic recrystallization was also documented. Furthermore, it was revealed that the Al/Si cells contribute significantly to grain refinement. EBSD/TKD investigations showed that cell misorientation increased after ECAP processing, resulting in an increased fraction of grains with very low misorientation angles.

Aluminium finds wide application in mechanical engineering due to its low density and corrosion resistance. In this research, aluminium was subjected to two different metal forming technologies-cold forging (upsetting) and equal channel angular pressing (ECAP)-to obtain improvement in its exploitation properties. Parallel to changing mechanical properties by using these two processes, there was a change in the microstructure of the material. The resulting microstructures were examined using an optical microscope. A different treated aluminium was subjected to erosion wear in various time intervals. Wear testing was conducted for two different impingement angles causing abrasive wear and impact wear. The erosion mechanisms were examined by scanning electron microscopy. These results showed that there is no statistically significant difference in erosion wear for different states at the same impingement angle. However, the difference is noticeable at different wear angles. The significance of the difference in wear of the samples treated with the forging and ECAP techniques was validated by statistical analysis with tests of different sensitivities. The results of the t-test showed that ECAPed samples present a statistically significant difference in the loss of mass due to variations in erosion angle during the 30, 45, and 60 min wearing. A substantial difference in the change in sample mass is also visible for the forged state worn for 60 min.

Improving the comprehensive performance of low alloyed Mg is a significant challenge for biomedical applications. This paper developed a high-performance Mg-Zn alloy with uniform ultrafine grains and nano-precipitates through a straightforward, high-temperature reciprocating equal channel angle extrusion (ECAP) process and researched the microstructure, mechanical property, degradation behaviour, and biocompatibility of the developed alloy. Results showed that the lean Mg-2Zn alloy successfully refined grain to about 1 μm and produced plenty of nano-particles with uniform distribution, providing high comprehensive mechanical properties (YS: 235 MPa, UTS: 267 MPa, EL: 15.6 %). Additionally, Zn-riched nano-particles in the matrix could decrease the Zn aggregation at the corrosion layer-matrix interface and form a dense oxide film, achieving a low degradation rate (0.13 mm/year in vivo). Finally, this work realizes the low alloy content, low cost, and good properties of one biodegradable Mg alloy, which will benefit the promotion of future clinical applications.

Magnesium, valued for its lightweight, recyclability, and biocompatibility, faces challenges like its poor wear behavior and mechanical properties that limit its adaptation for a multitude of applications. In this study, various statistical analyses, and machine learning (ML) techniques were employed to optimize equal channel angular pressing (ECAP) process parameters for improving the wear behavior of Mg-3wt.% Zn-0.7 wt% Ca alloy. ECAP was conducted up to four passes via route Bc at 250 °C. Wear testing of both as-annealed (AA) and ECAP-processed alloys was performed using the dry ball-on-flat wear method under varying loads, speeds, and time. One pass (1P) and 4Bc-ECAP resulted in a notable uniform grain refinement of 86 % and 91 %, respectively, compared to the AA. X-ray diffraction (XRD) analysis confirmed a refined structure attributed to extensive dynamic recrystallization. Mechanical wear testing revealed a significant reduction in volume loss (VL), up to 56 % and 28.5 % after 1P and 4Bc samples, respectively, compared to the AA sample, supported by the observed texture intensity. The coefficient of friction (COF) stabilizes at 0.30-0.45, indicating low friction characteristics. Next, by adjusting wear load and speed through design of experiments (DOE), the wear output responses, VL and COF, were experimentally investigated. The output responses were predicted in the second step using ML, 3D response surface plots, and statistical analysis of variance (ANOVA). According to the regression model, the minimal VL was attained at a 5 N applied load. Also, the wear speed and VL at different passes are inversely proportional. On the other hand, the optimal COF was obtained at applied load about 2-3 N and 250 mm/s at different passes. The wear process variables were then optimized using different optimization techniques namely, genetic algorithm (GA), hybrid DOE-GA, and multi-objective genetic algorithm (MOGA) approaches.

BACKGROUND: Drawbacks of fixed-output spinal cord stimulation (SCS) screening trials may lead to compromised trial outcomes and poor predictability of long-term success. Evoked compound action potential (ECAP) dose-controlled closed-loop (CL) SCS allows objective confirmation of therapeutic neural activation and pulse-to-pulse stimulation adjustment. We report on the immediate patient-reported and neurophysiologic treatment response post-physiologic CL-SCS and feasibility of early SCS trial responder prediction.
METHODS: Patient-reported pain relief, functional improvement, and willingness to proceed to permanent implant were compared between the day of the trial procedure (Day 0) and end of trial (EOT) for 132 participants in the ECAP Study undergoing a trial stimulation period. ECAP-based neurophysiologic measurements from Day 0 and EOT were compared between responder groups.
RESULTS: A high positive predictive value (PPV) was achieved with 98.4% (60/61) of patients successful on the Day 0 evaluation also responding at EOT. The false-positive rate (FPR) was 5.6% (1/18). ECAP-based neurophysiologic measures were not different between patients who passed all Day 0 success criteria (\"Day 0 successes\") and those who did not (\"needed longer to evaluate the therapy\"). However, at EOT, responders had higher therapeutic usage and dose levels compared to non-responders.
CONCLUSIONS: The high PPV and low FPR of the Day 0 evaluation provide confidence in predicting trial outcomes as early as the day of the procedure. Day 0 trials may be beneficial for reducing patient burden and complication rates associated with extended trials. ECAP dose-controlled CL-SCS therapy may provide objective data and rapid-onset pain relief to improve prognostic ability of SCS trials in predicting outcomes.
BACKGROUND: The ECAP Study is registered with ClinicalTrials.gov (NCT04319887).

This study investigates the effects of zinc (4 wt.%) and severe plastic deformation on the mechanical properties of AZ61 magnesium alloy through the stir-casting process. Severe plastic deformation (Equal Channel Angular Pressing (ECAP)) has been performed followed by T4 heat treatment. The microstructural examinations revealed that the addition of 4 wt.% Zn enhances the uniform distribution of β-phase, contributing to a more uniformly corroded surface in corrosive environments. Additionally, dynamic recrystallization (DRX) significantly reduces the grain size of as-cast alloys after undergoing ECAP. The attained mechanical properties demonstrate that after a single ECAP pass, AZ61 + 4 wt.% Zn alloy exhibits the highest yield strength (YS), ultimate compression strength (UCS), and hardness. This research highlights the promising potential of AZ61 + 4 wt.% Zn alloy for enhanced mechanical and corrosion-resistant properties, offering valuable insights for applications in diverse engineering fields.

Histospecification and morphogenesis of anthers during development in Arabidopsis (Arabidopsis thaliana) are well understood. However, the regulatory mechanism of microsporocyte generation at the pre-meiotic stage remains unclear, especially how archesporial cells are specified and differentiate into 2 cell lineages with distinct developmental fates. SPOROCYTELESS (SPL) is a key reproductive gene that is activated during early anther development and remains active. In this study, we demonstrated that the EAR motif-containing adaptor protein (ECAP) interacts with the Gro/Tup1 family corepressor LEUNIG (LUG) and the BES1/BZR1 HOMOLOG3 (BEH3) transcription factor to form a transcription activator complex, epigenetically regulating SPL transcription. SPL participates in microsporocyte generation by modulating the specification of archesporial cells and the archesporial cell-derived differentiation of somatic and reproductive cell layers. This study illustrates the regulation of SPL expression by the ECAP-LUG-BEH3 complex, which is essential for the generation of microsporocytes. Moreover, our findings identified ECAP as a key transcription regulator that can combine with different partners to regulate gene expression in distinct ways, thereby facilitating diverse processes in various aspects of plant development.

The hexagonal close-packed (HCP) crystal structure of Mg alloys lead to poor formability as well as other undesirable mechanical behaviors in an otherwise highly sought-after alloy for commercial use. This study investigates the evolution of microstructure, texture, corrosion and mechanical behaviors in Mg-Zn-Mn (ZM31) alloy after processing using Equal Channel Angular Pressing (ECAP). Dynamic recrystallization was evident in the ECAP-processed samples, correlated with a substantial fiber structure, and resulted in the attainment of notable grain refinement and high lattice strain. Average grain sizes of 2.2 and 2 μm were achieved via 2 and 4-Pass Bc processing, respectively. This significant refinement yielded lower corrosion rates through enhancement of the thickness, coherency, and stability of formed protective oxide layers. The corrosion rate in the NaCl medium was substantially enhanced by 99.5% after four passes via route Bc. The recrystallized fine structure was found to have contributed to yield strength, ultimate strength, and microhardness improvements. Deformation enhanced yield and ultimate strengths by 132% and 64%, respectively. The distinctive grain refinement mechanism exhibited through the current ECAP procedure has potential to pave the way for novel and impactful utilizations of ZM31 in industries that demand exceptional mechanical and corrosion performance.

OBJECTIVE: The hearing outcomes of cochlear implant users depend on the functional status of the electrode-neuron interface inside the cochlea. This can be assessed by measuring electrically evoked compound action potentials (eCAPs). Variations in cochlear neural health and survival are reflected in eCAP-based metrics. The difficulty in translating promising results from animal studies into clinical use has raised questions about to what degree eCAP-based metrics are influenced by non-neural factors. Here, we addressed these questions using a computational model.
METHODS: A 2-D computational model was designed to simulate how electrical signals from the stimulating electrode reach the auditory nerve fibers distributed along the cochlea, evoking action potentials that can be recorded as compound responses at the recording electrodes. Effects of physiologically relevant variations in neural survival and in electrode-neuron and stimulating-recording electrode distances on eCAP amplitude growth functions (AGFs) were investigated.
RESULTS: In line with existing literature, the predicted eCAP AGF slopes and the inter-phase gap (IPG) effects depended on the neural survival, but only when the IPG effect was calculated as the difference between the slopes of the two AGFs expressed in linear input-output scale. As expected, shallower eCAP AGF slopes were obtained for increased stimulating-recording electrode distance and larger eCAP thresholds for greater electrode-neuron distance. These non-neural factors had also minor interference on the predicted IPG effect.
CONCLUSIONS: The model predictions demonstrate previously found dependencies of eCAP metrics on neural survival and non-neural aspects. The present findings confirm data from animal studies and provide insights into applying described metrics in clinical practice.