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Povzetek: To optimize the removal of cancerous prostate tissue, nerve-sparing robot-assisted radical prostatectomy (RARP) is commonly used. This technique aims to preserve the neurovascular bundles (NVBs), damage to which is a major cause of postoperative erectile dysfunction (ED). The primary goal of this study was to develop and assess a novel intraoperative NVB stimulation (NVBS) system designed to elicit penile erectile responses during RARP and assist in predicting postoperative erectile function (EF). The stimulation paradigm involved applying trains of rectangular and quasi-trapezoidal stimulating pulses (stimuli) to the apical, mid, and basal portions of the NVBs for approximately 60 s, both before and after the nerve-sparing dissection. The stimulation probe was developed with a consideration of nerve-stimulation models, NVB anatomy, and surgical constraints. Electrodes made of platinum were embedded in denture-grade material and mounted in a titanium housing. To evaluate the erectile responses, a multi-sensor probe was designed to monitor axial penile rigidity (ARIG), galvanic skin response (GSR), and glans temperature Tgp. Additionally, corpus cavernosum electromyography (CC-EMG) was recorded using surface and needle electrodes. Among five male patients enrolled, two showed noticeable CC-EMG activity, but none demonstrated a measurable increase in axial penile rigidity. The CC-EMG data were limited to short-term monitoring and could not be reliably analyzed in the time or frequency domains. In conclusion, although the stimulation protocol did not trigger measurable erectile responses, CC-EMG signals offered intraoperative insights into NVB integrity. This information may support more accurate predictions of erectile function recovery following RARP.
Ključne besede: robot-assisted radical prostatectomy, neurovascular bundles, electrical nerve stimulation, physiological measurements
Objavljeno v DiRROS: 12.02.2026; Ogledov: 478; Prenosov: 161
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Ključne besede: directed energy deposition, powder stream, discrete element method, computational fluid dynamics
Objavljeno v DiRROS: 09.12.2025; Ogledov: 465; Prenosov: 297
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Povzetek: Understanding material transformations at the nano- and microscale is essential for advancing electrocatalysis, energy storage, and other applications. Conventional SEM imaging, which captures random locations before and after treatment, struggles to distinguish real transformations from inherent sample heterogeneity. Identical Location SEM (IL-SEM) overcomes this by enabling re-imaging of the exact same region, offering clear evidence of localized changes in morphology, structure, and composition. Despite its simplicity and wide applicability, IL-SEM remains underutilized. This article presents a detailed, practical guide to implementing IL-SEM reliably, including sample alignment, multiscale imaging, and consistent re-localization. Key methodological tips and solutions to common challenges are provided, making the approach accessible even for non-expert users. To showcase its versatility, we present case studies involving electrocatalysts, alloys, and nanostructured materials. Moreover, by integrating IL-SEM with energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD), we demonstrate how compositional and crystallographic evolution can be tracked alongside morphological changes. This optimized workflow offers a powerful, non-destructive method for visualizing dynamic material behavior and provides a foundation for IL-SEM to become a standard technique for studying structural evolution across diverse materials research fields.
Ključne besede: electrocatalysis, identical location electron microscopy, IL-SEM, materials characterization, scanning electron microscopy, surface analysis
Objavljeno v DiRROS: 15.10.2025; Ogledov: 690; Prenosov: 387
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Povzetek: Metal-based Directed Energy Deposition (DED) is considered one of the variations of additive manufacturing with the highest potential, particularly for space industry and in-orbital manufacturing. The technology however still faces various challenges, many of which can be traced back to poor control and understanding of the powder delivery. Velocity distribution of powder particles at the DED nozzle outlet has a key influence on the results of any predictive model of powder stream and yet remains largely disputed. Certain numerical studies highlighted a possible influence of powder particle size on the velocity condition at the nozzle exit, yet no experimental studies confirmed this effect. The experimental campaign described in this paper quantifies this relation between powder particle size and velocity distribution at the nozzle outlet and a strong decrease of particle speed with particle size is observed. Moreover, smaller particles are observed to travel at speeds higher than the mean carrier gas speed suggesting powder particle segregation within the nozzle as one of the mechanisms driving speed differences at the nozzle outlet.
Ključne besede: directed energy deposition, powder stream, boundary conditions, particle velocity distribution
Objavljeno v DiRROS: 19.09.2025; Ogledov: 548; Prenosov: 347
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Povzetek: This study examines the effect of Gaussian and ring-shaped laser beam profiles on the microstructural development and mechanical properties of the PBF-LB/M processed nickel-based alloy Inconel 718 in its as-built and post-heat-treated conditions. Beam shaping was employed to achieve a faster build rate without compromising material properties. One of the objectives was to optimise heat treatment conditions for the beam-shaped profile. The post-heat-treatment process included four different solution annealing temperatures (954 °C, 984 °C, 1034 °C and 1154 °C), followed by two-step ageing, respectively. The microstructure evolution was revealed using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray diffraction (EDS). The mechanical properties in all investigated conditions were evaluated based on tensile tests at room temperature. Using a Gaussian laser beam profile results in a fine-grained microstructure without a strong columnar orientation, while the ring beam profile produces a distinct columnar structure with larger nanodendritic grains and dislocation cells. Both beam profiles exhibit a similar proportion of Laves phase. After post-heat treatment, the Gaussian beam profile generally provides 3-7 % higher mechanical properties. The differences in mechanical properties between horizontal and vertical building directions are greater for ring-shaped laser beam profiles. Heat-treatment temperature above 1034 °C leads to recrystallisation, grain growth and the formation of carbonitrides which reduce mechanical properties. Based on the results, the proposed optimal heat-treatment temperature for both investigated laser beam shapes is 984 °C. At this temperature, tensile strength equalises between horizontal and vertical build directions while yield strength increases, which is beneficial for most applications.
Ključne besede: PBF-LB/M, beam shaping, IN718, heat treatment, mechanical properties
Objavljeno v DiRROS: 07.07.2025; Ogledov: 900; Prenosov: 453
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