Search Results (144)

The deep inferior epigastric perforator (DIEP) flap holds its place as the gold standard approach for autologous tissue breast reconstruction given the strong durability, favorable donor site morbidity, and high patient satisfaction overall. With the reliability and safety of microsurgical reconstruction of the breasts being well-established over these last decades, the goals of DIEP flap reconstruction have expanded beyond flap survival toward optimization of aesthetic, patient-reported, and quality-of-life outcomes. Achieving ideal cosmesis requires thoughtful decision-making across the reconstructive continuum, including of radiation timing, mastectomy incision design, nipple–areolar complex management, reconstructive sequencing, flap shaping and inset, abdominal closure, neurotization, and the potential role of any revision or adjunctive procedures. Modern techniques including delayed-immediate reconstruction, nipple delay, free nipple grafting, fat grafting, and abdominal wall reinforcement have expanded the availability of personalized care in breast reconstruction. This narrative review integrates a targeted literature search with consensus-driven expert opinion informed by our senior authors’ extensive cumulative experience performing DIEP flap breast reconstruction. It discusses principles, technical strategies, and evolving evidence for optimizing aesthetic outcomes in DIEP flap breast reconstruction while preserving safety and minimizing morbidity. Full article

A numerical design study is carried out to support the setup of a wind tunnel experiment for the flap cover seal, which will serve as a benchmarking reference database for Fluid–Structure Interaction (FSI) in aeronautics. To this end, 3-D scale-resolving unsteady Large Eddy Simulation (LES) with the Lattice Boltzmann Method (LBM) is carried out using the simulation software ProLB. A new aerodynamic layout for the chosen F15LS (Large-Scale) high-lift wing model is established to fit the high-lift wing in the DLR-AWB tunnel. The design process involves variations in the leading-edge nose contour’s streamwise length and camber lines (inducing a negative S-shape) to reduce the leading-edge suction peak, thereby lowering the absolute lift while preserving the flap operating conditions. Initial simulations utilize a simplified periodic LES slice and a theory of the method of images to model wind tunnel jet flow deflection, culminating in a full-span 3-D WM-LES-LBM simulation of the entire wind tunnel installation, including free shear layers, to confirm the designed performance of the modified F15LS. This simulation serves to make informed decisions on model settings such as the boundary layer fence and model-nozzle distance. The successful experimental validation of critical performance characteristics, including angle-of-attack requirements and flow deflection, confirms the fidelity of the pre-test WM-LES-LBM evaluation. Full article

To address the limited understanding of the aerodynamic characteristics of bird-inspired flapping-wing aircraft across different flight phases and the unclear flow field interaction mechanisms between the wings and tail, this study performs three-dimensional numerical simulations based on a self-developed prototype using ANSYS Fluent and the overset mesh method. The aerodynamic effects of key tail parameters under different flight conditions are quantitatively evaluated, and the mechanisms of bidirectional wing–tail aerodynamic coupling are investigated. The results show that tail twist has a negligible influence on instantaneous lift and thrust during level flight, with a maximum variation of only 0.2 N, but significantly affects the overall aerodynamic moments of the aircraft. When the tail twist angle increases from 15° to 20°, the pitching moment increases by 6%. In contrast, during climbing flight, the tail pitch angle has a pronounced effect on lift and thrust, and its aerodynamic influence depends strongly on the aircraft angle of attack. At an aircraft angle of attack of 15°, the difference between the maximum and minimum cycle-averaged pitching moments reaches 0.2 N·m. Further analysis of vorticity fields and pressure distributions confirms the existence of distinct wing–tail aerodynamic coupling. The tail not only directly modifies the aerodynamic forces and moments acting on the aircraft but also alters the wing-generated flow structures, while the wing wake simultaneously influences the aerodynamic effectiveness of the tail. This bidirectional wing–tail aerodynamic coupling plays a critical role in shaping the aerodynamic response of the aircraft under different flight conditions. These findings clarify the aerodynamic roles of key tail parameters and reveal the underlying flow field interaction mechanisms across different flight phases, providing a theoretical basis for motion-parameter optimization and precise attitude control of bird-inspired flapping-wing aircraft. Full article

Background: Despite the rise of endoscopic approaches, the direct brow lift remains one of the most effective procedures for correcting brow ptosis for both functional and cosmetic indications. It continues to offer superior control when correcting brow shape, height, and asymmetry. However, visible scarring remains a concern. This systematic review was conducted to synthesize recent evidence on strategies that minimize visible scarring in direct brow lift surgery. Methods: A systematic literature search was performed to retrieve English-language publications from the past decade, discussing scar-minimization strategies in direct brow lift. A total of 124 records were identified through database searches in Ovid MEDLINE and Embase. Records were screened manually according to predetermined criteria, and those not in English, not addressing scarring, or not focused on direct brow lift were excluded. After this process, ten publications were included in the final qualitative synthesis. Results: The qualitative synthesis of all included publications (together comprising data on approximately 900 patients) revealed several strategies for scar minimization. (1) Incision beveling: A shallow cranially directed bevel between 20° and 45° preserves brow hair follicles and allows hair regrowth through the scar, providing natural camouflage. (2) Undermining: Gentle subcutaneous undermining in a limited 1–2 cm field, while preserving subcutaneous fat, allows tension-free advancement and maintains brow volume. (3) Periosteal suspension: Anchoring the mobilized brow flap to the frontal periosteum redistributes tension away from the dermal closure, maintaining elevation and improving scar quality. (4) Layered closure: Two- or three-layered wound closure with deep dermal anchoring and fine everting skin sutures minimizes dermal traction and scar widening. (5) Adjunctive measures: Evidence for topical silicone gel was inconclusive, whereas postoperative laser therapy and perioperative neuromodulator use demonstrated improved scar appearance. Across studies, outcomes were consistent, with high patient satisfaction, inconspicuous scars in over 85% of cases, and low complication or revision rates. Conclusions: Direct brow lift has historically been criticized for conspicuous scarring, contributing to the popularity of endoscopic techniques. Nevertheless, the traditional direct brow lift remains a fundamental skill in the oculofacial plastic surgeon’s armamentarium, offering unmatched accuracy in brow repositioning, reliability, and symmetry. Contemporary evidence demonstrates refinements that can markedly minimize scar visibility. This systematic review and qualitative synthesis allow us to continue to refine and improve our techniques to minimize scarring in direct brow lift to the benefit of our patients. Full article

Birds actively modulate their wing and tail morphologies to achieve high aerodynamic efficiency and maneuverability, enabling long-duration gliding while retaining the ability to execute rapid maneuvers. Innovations in aircraft design and control are increasingly inspired by these avian flight characteristics through control surfaces that imitate the natural wing and tail movements of birds. This paper presents a non-flapping, unmanned aerial vehicle (UAV), called “SMART Hawk” (Shape-Morphing Artificial Red-Tailed Hawk), inspired by the flight and physical characteristics of Buteo jamaicensis, known as the Red-Tailed Hawk (RTH), which exhibits excellent soaring abilities and agility characteristic of birds of prey. To determine the design parameters required for flight, a mathematical model was developed in MachUpX, then validated and refined using Reynolds-averaged computational fluid dynamics (CFD) models in ANSYS Fluent. SMART Hawk incorporates biomimetic wing and tail morphing, including coordinated forward sweep of the mid-wing and aft sweep of the outer wing, as well as active tail pitch, roll, and feather tucking and expansion. The drone was manufactured from a combination of composite, wood, and 3D-printed components. Multiple flight tests were conducted with proof-of-concept prototypes to demonstrate the design’s effectiveness. Full article

Introduction: Standard abdominoplasty inevitably causes scarring in the umbilical region. Given the aesthetic significance of the navel, as the central anatomical landmark of the anterior abdominal wall, techniques that preserve the natural anatomy are warranted. The criteria for patient selection for such operations remain poorly defined, limiting their clinical application. Objective: The aim of this study was to define the indications and contraindications for scarless abdominoplasty in the umbilical region through a comparative analysis of clinical and subjective outcomes. Materials and Methods: A comparative study was conducted involving 115 patients operated on between 2021 and 2026. The experimental group consisted of 32 patients who underwent abdominoplasty without scarring in the umbilical region, while the control group comprised 83 patients who underwent standard abdominoplasty with umbilical transposition. The technique of scarless abdominoplasty in the umbilical region entailed limited mobilization of the cutaneous–subcutaneous flap, energy-based ultrasound-assisted liposuction in the supraumbilical region, suturing of rectus abdominis diastasis when clinically indicated, and fixation of the umbilicus in its physiological position without a skin incision around it. Energy-based ultrasound-assisted liposuction permits skin contraction in the supraumbilical area through a controlled internal thermal effect. The incidence of complications and BODY-Q questionnaire outcomes were evaluated at 3 months, 6 months, and one year. No significant differences in baseline clinical characteristics were observed between the groups. Results: The overall rate of postoperative complications in the experimental group was 18.8% (n = 6), compared to 24.1% (n = 20) in the control group; the difference was not statistically significant (p > 0.05). According to the BODY-Q questionnaire, patients in the experimental group reported significantly higher satisfaction with scar appearance (91.0 ± 3.5 vs. 83.0 ± 5.7; p < 0.001) and the umbilical region. The umbilicus retained its anatomically natural shape and depth. The use of energy-based ultrasound-assisted liposuction in the supraumbilical area contributed to the contraction of the upper cutaneous–subcutaneous flap, which made it possible to prevent extensive mobilization and the formation of a significant scar around the umbilicus in these patients. Conclusions: Scarless abdominoplasty in the umbilical region is a safe and effective technique in appropriately selected patients. Energy-based ultrasound-assisted liposuction produces an internal thermal effect that enhances the contraction of the cutaneous flap. Indications for this method comprise a moderate amount of excess skin tissue in the supraumbilical region, preserved skin elasticity, a normal or high umbilical position, and rectus abdominis diastasis grade I–II. Contraindications include pronounced excess skin tissue in the supraumbilical region, a low umbilical position, and general somatic contraindications to surgery. Full article

This paper presents the development of a novel morphing wing prototype with three camber-twist morphing flaps. Reflexed airfoil morphing is achieved by means of two chordwise degrees-of-freedom, thereby decoupling lift from the aerodynamic moment with respect to the aerodynamic centre. The prototype wing design is characterised by a novel morphing flap concept and driven by the boundary conditions pertinent to the wind tunnel testing facilities and the choice of research questions. The flaps’ spanwise ends are adapted to represent a seamless and a discontinuous transition between adjacent flaps. Linear electric motors induce the morphing shapes, equipped with load cells on their respective push rods, for actuator force measurement. Pressure taps are included to measure the pressure distribution along the wing section. Upon manufacturing, preliminary static test results validate the wing’s morphing functionality. The morphing trailing edge demonstrates a range of camber morphing and twist morphing shapes, as well as the ability to support asymmetric morphing between adjacent flaps. Full article

The use of an omental pedicle flap as an adjuvant treatment has gained popularity in veterinary medicine due to its versatility. This technique has been successfully applied in both intra-abdominal and extra-abdominal surgeries in human as well as veterinary medicine. In most intra-abdominal procedures, the greater omentum can be easily accessed through a midline laparotomy and directed to the area of interest. However, dogs and cats are typically positioned in lateral recumbency for extra-abdominal surgeries involving the thorax or limbs. In such cases, a lateral approach to the greater omentum could minimize the risk of infection or trauma associated with patient repositioning. This cadaver study evaluated the feasibility of accessing the greater omentum through a lateral approach laparotomy in both left and right lateral recumbency. A total of 22 cadavers (13 cats and 9 dogs) were included. Dorsal extension of the greater omentum was successfully performed in all specimens without major structural damage. Further elongation using an inverted L-shaped pedicle flap was achieved without rupture in 17 of 22 cadavers (77.3%). The results demonstrate that lateral approach laparotomy provides reliable access to the greater omentum and allows successful mobilization of the omentum for potential extra-abdominal applications, with no significant differences observed between left and right lateral approaches. This technique may represent a useful alternative in clinical situations where repositioning the patient is not feasible or carries increased surgical risk. Full article

Objective: To investigate the method and clinical outcomes of employing plantar propeller perforator flaps for the repair of defects in the plantar region. Methods: This was a retrospective case series of 40 patients (20 males, 20 females; age range 20–75 years) who underwent plantar defect reconstruction using the horn-shaped perforator flap technique between January 2020 and October 2025. Defect etiologies included malignant melanoma (n = 24), melanocytic nevus (n = 3), and refractory wounds (n = 13). Defect sizes ranged from 2 cm × 1.5 cm to 5 cm × 5 cm. The primary outcome was flap survival; secondary outcomes included functional recovery (American Orthopaedic Foot and Ankle Society AOFAS score), sensory recovery (Semmes–Weinstein monofilaments), and time to full weight-bearing. Results: Complete flap survival was achieved in 38/40 patients (95%). Two patients (5%) experienced minor distal wound dehiscence and necrosis, successfully managed with full-thickness skin grafting and dressing changes without compromising final outcomes. Mean follow-up was 14.2 ± 6.8 months (range 3–24 months). Mean AOFAS score was 91.3 ± 5.6, with 80% achieving excellent functional recovery. Protective sensation was present in 87.1% of the tested patients. Mean time to full weight-bearing was 6.4 ± 1.8 weeks. No local tumor recurrence occurred in melanoma patients during follow-up. Conclusions: The horn-shaped perforator flap provides a reliable source of homologous glabrous skin for reconstructing small-to-medium-sized plantar defects while avoiding skin grafting at the donor site. Its combined rotation–advancement mechanism, flexible triangular leading-edge strategies, and preservation of multiple perforators contribute to favorable functional and aesthetic outcomes. Prospective comparative studies with standardized plantar-specific outcome measures are warranted. Full article

As the population increases, the demand for power continues to rise. As fossil fuel resources reduce, wind energy emerges as a sustainable alternative and helps address adverse effects of global warming and environmental pollution caused by fossil fuels. Thus, this study focuses on increasing the efficiency of wind turbines by improving their energy conversion. In this study, the NREL Phase VI wind turbine blade was modified by adding a Gurney flap at trailing edge along the entire span. Computational fluid dynamics simulations using ANSYS CFX 19.2 were performed on the modified blades to evaluate their aerodynamic performance. Three different flap lengths were investigated with six wind speeds varying from 5 m/s to 20 m/s. The results obtained were compared with those from NREL Phase VI original shape and a blade equipped with a winglet. Computational domain was divided into a rotating cylindrical region and a stationary rectangular part. The aerodynamic parameters calculated include torque, thrust, and normal and tangential forces coefficients. At low velocities, the addition of a Gurney flap had an insignificant impact on torque and thrust, whereas at medium to high wind speeds, significant increases were observed on torque, indicating more power production. Full article

Surgery continues to represent the central curative modality for melanoma despite major advances in systemic immunotherapy and targeted treatments. Contemporary surgical strategies aim to maintain oncologic safety while minimizing functional and aesthetic morbidity through optimized excision margins, highly selective use of sentinel lymph node biopsy (SLNB), and the omission of routine completion lymph node dissection (CLND). Rapid integration of neoadjuvant and adjuvant immunotherapies has begun to redefine surgical indications, timing, and extent—particularly for intermediate-stage and locoregionally advanced disease. Parallel innovations in Mohs micrographic surgery, reconstructive flap design, lymphatic reconstruction, and minimally invasive techniques further broaden the possibilities for individualized intervention. This expanded review synthesizes current evidence, ongoing controversies, and emerging trends that are shaping the future of melanoma surgery, highlighting how precision oncology, immunologic profiling, and technological advances are transforming the surgeon’s role and enabling more tailored, less invasive, and outcome-focused management. Full article

The present study demonstrates a step-by-step method for optimizing the outflow valve geometry and maximizing thrust generation. In this system, the skin-mounted OutFlow Valve (OFV) acts as a convergent–divergent nozzle and, as such, the De Laval nozzle equations are considered as guidance for the shape optimization. The performance of the skin-mounted flapped OFV optimized designs is assessed with a combination of analytical equations and Computational Fluid Dynamics (CFD) methods. The three-dimensional Reynolds-Averaged Navier–Stokes (RANS) yield reliable thrust recovery estimates and reveal key aspects of the aerodynamic flow behaviour through the valve, highlighting the interaction between the skin-mounted flapped OFV components. The results compare well with the analytical approach, providing a basis upon which a skin-mounted flapped OFV can be tailored for a specific mission. Full article

Thermal stratification in deep reservoirs can cause ecologically problematic cold-water releases, and many existing selective-withdrawal phenomena rely on a limited set of fixed intake levels, which constrains their ability to follow seasonal shifts in the thermocline. Stepless stratified intakes with continuously adjustable flap gates offer quasi-continuous control of withdrawal depth, but their multi-gate, multi-brace layouts generate complex internal hydraulics whose energy-loss mechanisms are not well captured by conventional head-loss and resistance-coefficient metrics. In this study, physical-model measurements are combined with a validated three-dimensional numerical model, and entropy-production theory is used as a diagnostic to resolve where and by which mechanisms mechanical energy is irreversibly degraded inside a single-unit stepless stratified intake. The analysis shows that turbulent entropy production accounts for more than 98% of total dissipation, concentrated mainly in the flow channel and gate shaft, while the reservoir and outlet pipe contribute only weakly. Local entropy-production-rate fields indicate that dominant irreversibilities are associated with flow turning at the active gate leaves and with separation and wake development around horizontal and vertical braces, which generate low-velocity bands across gate levels and a low-velocity corridor in the shaft. Five geometric modification schemes targeting gate-entrance shaping and brace layout are evaluated; a combined brace-alignment and edge-rounding configuration most effectively weakens dissipation hotspots, improves discharge sharing among gate levels and reduces total entropy production. These findings show that entropy-based diagnostics can complement traditional hydraulic indicators and provide effective guidance for the design and refinement of stepless stratified intake structures. Full article

Background: Digital pulp reconstruction with toe-based flaps reliably restores sensibility and contour, yet the healing behavior of viable subcutaneous fat remains underexplored. Because adipose tissue exhibits patient-specific regenerative and volumetric responses, its preservation represents a key element of personalized fingertip reconstruction. This study evaluates the outcomes of toe pulp flaps with targeted fat preservation to assess how individual tissue biology influences contour and functional recovery. Methods: We retrospectively reviewed consecutive digital reconstructions performed with free toe flaps and several variations (pulp toe flap, chimeric pulp toe flap, trimmed great toe flap and chimeric pulp+ trimmed great toe). Particular attention was given to healthy subcutaneous fat that was deliberately maintained or exposed to help shape the final contour. All patients were followed clinically and photographically until complete healing occurred. Results: A total of 126 patients underwent a finger reconstruction with free toe flaps and several variations. The preserved fat layer was intentionally left exposed to promote healthy granulation and spontaneous epithelialization, contributing favorably to the final contour of the distal pulp as the nail advanced. All wounds healed without the need for skin grafts. All patients achieved good to excellent functional and esthetic outcomes with minimal donor-site morbidity. Conclusions: This large retrospective series confirms the reliability of a healthy flap to help shape the digital reconstruction, highlighting the regenerative potential of viable digital fat. Incorporating this concept into the flap design may reduce the need for grafting, minimize donor-site morbidity, and enhance reconstructive outcomes in hand surgery. Full article

This study presents a frequency-domain analysis of a finite-element (FEM)-based rotor–nacelle model for wind turbines, validated against the open-source time-domain tool OpenFAST. The analysis was carried out using METHOD, an in-house computational framework implemented in Python. While time-domain models remain standard for nonlinear aeroelastic simulations, frequency-domain approaches offer advantages in early-stage design, control development, and system identification due to their efficiency, transparency, and suitability for parametric studies. The FEM model includes flexible blades, hub, and nacelle dynamics and includes tower and fixed or floating platform components with rotor–tower frequency interactions. In this work, a fixed tower is considered to isolate rotor behaviour. Beam-element formulation enables the computation of natural frequencies, mode shapes, and frequency response functions, and an equivalent rotor model is implemented in OpenFAST for consistent benchmarking. Validation results show close correspondence between the two modelling approaches. Key operational parameters agree within 3%, while structural responses, including flap-wise deflection, bending moments, and resultant quantities, typically fall within an overall accuracy range of 5–15%, consistent with expected differences arising from reference-frame conventions and modelling assumptions. Discrepancies are discussed in terms of numerical damping, model assumptions (differences in the axis system), and the influence of structural simplifications. Overall, the FEM model captures the dominant dynamic behaviour with satisfactory accuracy and a consistent orientation of global response. Computational efficiency results further highlight the advantages of the METHOD framework. Wind-field generation is completed roughly an order of magnitude faster, and long-duration aeroelastic simulations achieve substantial speed-ups, reaching more than one order of magnitude for multi-hour cases, demonstrating strong scalability relative to OpenFAST. Overall, the results confirm that a well-constructed yet still simplified frequency-domain FEM rotor model can provide a robust and computationally efficient alternative to conventional time-domain solvers. Moreover, the computational performance presented here represents a lower bound, as further improvements are readily achievable through parallelisation and solver-level optimisation. Future papers will present the full-system aero-hydro-elastic coupling for fixed and floating offshore wind turbine applications. Full article