This study evaluated the influence of vacuum carburizing parameters on the microstructure, microhardness profile, and case hardening depth (CHD550) of TL 4227 and TL 4521 steels used in highly loaded gear components. Experiments were performed on industrial gear components using an ALD ModulTherm system at 960, 980, and 1,000 °C, followed by gas quenching and tempering. The work focused on industrial validation of VW TL gear steels and shortened carburizing cycles based on previous temperature-focused results. Metallographic examination and microhardness profiling were performed to establish correlations between process parameters and case properties. CHD550 increased from approximately 0.65 mm to 0.9 mm with increasing carburizing temperature, while surface hardness remained around 740 HV1. A reduction of the total carburizing cycle time by approximately 15–20
Mining critical minerals in the Democratic Republic of Congo comes with tough governance hurdles, environmental damage, and deep socioeconomic strains. This study’s approach blends SWOT with PESTLE analysis, drawing on the insight of experts from 32 organizations in 11 countries, including Canada, France, Germany, India, Norway, Pakistan, Poland, Portugal, Romania, Spain, and the United States. This two‑pronged approach makes it easier to fully examine the structural, political, and socio‑environmental sides of the cobalt industry in the Democratic Republic of the Congo. The PESTLE analysis paints the DRC’s political climate as unstable and steeped in corruption, with social governance in deep crisis and environmental oversight falling far short. In the SWOT analysis, strengths at 14.49 and opportunities at 12.54 edge ahead of weaknesses at 12.95 and threats at 11.27 on average. This forms the foundation for the study’s conclusion: greater transparency in institutions, fairer labour market governance, and stronger environmental laws could help curb the extractive injustices tied to cobalt mining in the DRC.
This study presents an experimental–numerical investigation of the ballistic response of asymmetric sandwich structures with aluminum–ceramic composite foam cores, aluminum face sheets, and intermediate fiber-reinforced composite laminates with various stacking sequences. Particular emphasis is placed on the measurement methodology and quantitative evaluation of impact parameters.Ballistic tests were performed using 5.56 × 45 mm NATO M193 and SS109 projectiles and 7.62 × 51 mm NATO M80 bullets. Projectile velocities were determined using synchronized optical gates and high-speed camera imaging, enabling accurate pre- and post-impact velocity measurements and energy calculations. The recorded signals were processed to determine projectile velocity reduction, absorbed kinetic energy, and specific energy absorption, with repeatability verified through multiple trials.The results indicate that the laminate architecture significantly affects projectile destabilization and energy dissipation. Hybrid carbon–glass configurations provided the highest ballistic efficiency, reaching velocity reductions of up to 100 m/s for the M193 projectile. Finite element simulations conducted in Abaqus/Explicit with Johnson–Cook and Hashin damage models were validated against experimental data, showing residual velocity discrepancies below 3%.The proposed measurement framework enables reliable quantification of ballistic performance and provides a validated basis for the design and optimization of lightweight protective sandwich structures.
BackgroundIntermittent theta burst stimulation (iTBS) is increasingly explored as a non-invasive neuromodulatory approach capable of inducing long-lasting plasticity with potential therapeutic value in age-related neurological and psychiatric conditions. However, the cellular and molecular mechanisms underlying iTBS protocols remain largely unknown, limiting its further therapeutic development.MethodsHere, we investigated the behavioral, structural, synaptic, and calcium-dependent effects of a 7-day iTBS600 protocol using a combination of in vivo, ex vivo, and in vitro approaches. 2.5-months old male Wistar rats and Grin2A knockout mice were used.ResultsProlonged iTBS did not alter general locomotor activity, anxiety-like behavior, or short-term recognition memory, indicating preserved baseline behavioral function. Despite the absence of behavioral changes, prolonged iTBS induced robust structural plasticity in hippocampal CA1 neurons, increasing total spine density and selectively enhancing the proportion of thin, learning spines. Synaptosomal analysis revealed upregulation of GluN1 and GluN2A, elevated BDNF levels, and activation of downstream Akt, ERK1/2, and mTOR pathways. Prolonged iTBS also enhanced perineuronal net formation around PV+ interneurons across hippocampal subfields. In vitro recordings demonstrated increased spontaneous and evoked Ca2+ activity following both acute and prolonged stimulation, with the prolonged protocol uniquely extending the duration of K+-evoked Ca2+ responses. Pharmacological blockade with D-AP5 and experiments in Grin2a-knockout neurons revealed that these effects are dependent on NMDA receptors, particularly the GluN2A subunit.ConclusionTogether, these findings indicate that prolonged iTBS drives coordinated structural, synaptic, and Ca2+-dependent plasticity in the hippocampus through GluN2A- and BDNF-dependent mechanisms. This work provides mechanistic insight into how iTBS may induce sustained circuit-level adaptations relevant for therapeutic applications.
Nerve transfers have shifted from “salvage” procedures to a primary, biology-based strategy for restoring priority function after severe peripheral nerve injury, particularly brachial plexus injury. In this invited opinion, we summarize the historical roots of nerve transfer surgery and outline the modern rationale for distal coaptation - shortening regeneration distance, bypassing scarred zones, and directing axons toward functionally critical targets while preserving native biomechanics. We discuss practical donor-recipient selection principles (redundancy, axonal capacity, proximity, and synergy) and contrast proximal versus distal transfer concepts within contemporary reconstructive algorithms.Using representative examples, we emphasize how distal transfers can be integrated with grafting, tendon transfers, or free muscle transfer in staged reconstructions. Based on our clinical experience across elbow, shoulder, and hand reinnervation, we highlight consistently high rates of functionally meaningful recovery and substantial improvements in patient-reported quality of life.
