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Many offshore geotechnical problems--such as cyclic T-bar penetration and lateral buckling of pipelines--are affected by the tendency of fine-grained soils to strain-soften due to remoulding. Careful calibration of the constitutive model parameters that control strain softening is essential for accurate simulation of these processes. This is usually achieved by matching constitutive model response with standard element test data, which implicitly assumes that homogeneous stress/strain fields exist within the sample. However, popular element test protocols (e.g., triaxial, simple shear) cannot apply sufficient deformation-- at least as measured at the boundaries--to achieve fully remoulded conditions. This work explores the potential to determine strain-softening parameters experimentally, directly from image-based full-field deformation measurements and external loading data. Artificial data generated from finite element simulations of biaxial compression and T-bar penetration tests, using a non-locally regularised strain-softening constitutive model based on Modified Cam Clay, are then used to demonstrate the potential of the proposed technique. The results demonstrate significant potential for the application of the technique to identify constitutive parameters from full-field measurements even when polluted with modest measurement noise. Key words: large deformation modelling, particle image velocimetry, full-field deformation measurement, constitutive parameter calibration, 1. Introduction Geotechnical problems--particularly in the field of offshore geomechanics----often involve significant remoulding of soil due to large movements of structural elements. Selected examples of such problems are cyclic T-bar [...]

Background: Current clinical approaches to regenerate temporomandibular joint (TMJ) articulating cartilage defects only treat the symptoms (i.e. pain and dysfunction) and do not seek to restore joint integrity for long‐term relief. Therefore, we investigated a novel self‐assembling tissue‐engineered cartilage to overcome this significant clinical issue for TMJ regenerative purposes. Objectives: Examine the maturation of dynamic self‐regenerating cartilage (dSRC) using auricular chondrocytes and evaluate a novel combinatorial approach with fractional laser treatment and dSRC implantation for TMJ cartilage repair. Materials and Methods: A suspension of 107 freshly harvested rabbit ear chondrocytes was cultured under a continuous reciprocating motion to form the dSRC. After 2, 4 and 8 weeks of culture, dSRC samples were stained with H&E, Safranin‐O and Toluidine Blue. Immunohistochemistry (IHC) was performed for collagens type I and II. Channels (300–500 μm diameter and 1.2–1.5 mm depth) were created in six freshly harvested condyles using a fractional Erbium laser. Two groups were tested: dSRC in a laser‐ablated lesion (experimental) and an empty laser‐ablated channel (control). TMJ condyles were cultured for up to 8 weeks and analysed as described above. Results: H&E staining showed a high cell density in dSRC compared to native cartilage. All dSRC groups demonstrated intense Safranin‐O staining, indicating high glycosaminoglycan (GAG) production and intense Toluidine Blue staining showed high proteoglycan content. IHC confirmed that dSRC consisted predominantly of collagen type II. The experimental group showed improved cartilage repair at both time points compared to the empty channels. Conclusion: dSRC viability and successful matrix formation were demonstrated in vitro. The combination of fractional laser ablation and dSRC implantation enhanced cartilage repair. [ABSTRACT FROM AUTHOR]

Objectives: This study investigated a novel strategy for improving regenerative cartilage outcomes. It combines fractional laser treatment with the implantation of neocartilage generated from autologous dynamic Self-Regenerating Cartilage (dSRC). Methods: dSRC was generated in vitro from harvested autologous swine chondrocytes. Culture was performed for 2, 4, 8, 10, and 12 weeks to study matrix maturation. Matrix formation and implant integration were also studied in vitro in swine cartilage discs using dSRC or cultured chondrocytes injected into CO2 laser-ablated or mechanically punched holes. Cartilage discs were cultured for up to 8 weeks, harvested, and evaluated histologically and immunohistochemically. Results: The dSRC matrix was injectable by week 2, and matrices grew larger and more solid with time, generating a contiguous neocartilage matrix by week 8. Hypercellular density in dSRC at week 2 decreased over time and approached that of native cartilage by week 8. All dSRC groups exhibited high glycosaminoglycan (GAG) production, and immunohistochemical staining confirmed that the matrix was typical of normal hyaline cartilage, being rich in collagen type II. After 8 weeks in cartilage lesions in vitro, dSRC constructs generated a contiguous cartilage matrix, while isolated cultured chondrocytes exhibited only a sparse pericellular matrix. dSRC-treated lesions exhibited high GAG production compared to those treated with isolated chondrocytes. Conclusions: Isolated dSRC exhibits hyaline cartilage formation, matures over time, and generates contiguous articular cartilage matrix in fractional laser-created microenvironments in vitro, being well integrated with native cartilage. [ABSTRACT FROM AUTHOR]

The current gold standard for preserving vascularized composite allografts (VCA) is 4°C static cold storage (SCS), albeit muscle vulnerability to ischemia can be described as early as after 2 h of SCS. Alternatively, machine perfusion (MP) is growing in theworld of organ preservation. Herein, we investigated the outcomes of oxygenated acellular subnormothermic machine perfusion (SNMP) for 24-h VCA preservation before allotransplantation in a swine model. Six partial hindlimbs were procured on adult pigs and preserved ex vivo for 24 h with either SNMP (n = 3) or SCS (n = 3) before heterotopic allotransplantation. Recipient animals received immunosuppression and were followed up for 14 days. Clinical monitoring was carried out twice daily, and graft biopsies and blood samples were regularly collected. Two blinded pathologists assessed skin and muscle samples. Overall survival was higher in the SNMP group. Early euthanasia of 2 animals in the SCS group was linked to significant graft degeneration. Analyses of the grafts showed massive muscle degeneration in the SCS group and a normal aspect in the SNMP group 2 weeks after allotransplantation. Therefore, this 24-h SNMP protocol using a modified Steen solution generated better clinical and histological outcomes in allotransplantation when compared to time-matched SCS. [ABSTRACT FROM AUTHOR]

Vascularized composite allografts (VCA) face ischemic challenges due to their limited availability. Reperfusion following ischemia triggers oxidative stress and immune reactions, and scavenger molecules could mitigate ischemia–reperfusion injuries and, therefore, immune rejection. We compared two scavengers in a myocutaneous flap VCA model. In total, 18 myocutaneous flap transplants were performed in Major histocompatibility complex (MHC)-defined miniature swine. In the MATCH group (n = 9), donors and recipients had minor antigen mismatch, while the animals were fully mismatched in the MISMATCH group (n = 9). Grafts were pretreated with saline, sodium iodide (NaI), or hydrogen sulfide (H2S), stored at 4 °C for 3 h, and then transplanted. Flaps were monitored until clinical rejection without immunosuppression. In the MATCH group, flap survival did not significantly differ between the saline and hydrogen sulfide treatments (p = 0.483) but was reduced with the sodium iodide treatment (p = 0.007). In the MISMATCH group, survival was similar between the saline and hydrogen sulfide treatments (p = 0.483) but decreased with the sodium iodide treatment (p = 0.007). Rhabdomyolysis markers showed lower but non-significant levels in the experimental subgroups for both the MATCH and MISMATCH animals. This study provides insightful data for the field of antioxidant-based approaches in VCA and transplantation. [ABSTRACT FROM AUTHOR]

Reconstructive techniques to repair severe tissue defects include the use of autologous fasciocutaneous flaps, which may be limited due to donor site availability or lead to complications such as donor site morbidity. A number of synthetic or natural dermal substitutes are in use clinically, but none have the architectural complexity needed to reconstruct deep tissue defects. The perfusion decellularization of fasciocutaneous flaps is an emerging technique that yields a scaffold with the necessary composition and vascular microarchitecture and serves as an alternative to autologous flaps. In this study, we show the perfusion decellularization of porcine fasciocutaneous flaps using sodium dodecyl sulfate (SDS) at three different concentrations, and identify that 0.2% SDS results in a decellularized flap that is efficiently cleared of its cellular material at 86%, has maintained its collagen and glycosaminoglycan content, and preserved its microvasculature architecture. We further demonstrate that the decellularized graft has the porous structure and growth factors that would facilitate repopulation with cells. Finally, we show the biocompatibility of the decellularized flap using human dermal fibroblasts, with cells migrating as deep as 150 µm into the tissue over a 7-day culture period. Overall, our results demonstrate the promise of decellularized porcine flaps as an interesting alternative for reconstructing complex soft tissue defects, circumventing the limitations of autologous skin flaps. [ABSTRACT FROM AUTHOR]

Background Photochemical tissue bonding (PTB) is a technique for peripheral nerve repair in which a collagenous membrane is bonded around approximated nerve ends. Studies using PTB with cryopreserved human amnion have shown promising results in a rat sciatic nerve transection model including a more rapid and complete return of function, larger axon size, and thicker myelination than suture repair. Commercial collagen membranes, such as dehydrated amnion allograft, are readily available, offer ease of storage, and have no risk of disease transmission or tissue rejection. However, the biomechanical properties of these membranes using PTB are currently unknown in comparison to PTB of cryopreserved human amnion and suture neurorrhaphy. Methods Rat sciatic nerves (n = 10 per group) were transected and repaired using either suture neurorrhaphy or PTB with one of the following membranes: cryopreserved human amnion, monolayer human amnion allograft (crosslinked and noncrosslinked), trilayer human amnion/chorion allograft (crosslinked and noncrosslinked), or swine submucosa. Repaired nerves were subjected to mechanical testing. Results During ultimate stress testing, the repair groups that withstood the greatest strain increases were suture neurorrhaphy (69 ± 14%), PTB with crosslinked trilayer amnion (52 ± 10%), and PTB with cryopreserved human amnion (46 ± 20%), although the differences between these groups were not statistically significant. Neurorrhaphy repairs had a maximum load (0.98 ± 0.30 N) significantly greater than all other repair groups except for noncrosslinked trilayer amnion (0.51 ± 0.27 N). During fatigue testing, all samples repaired with suture, or PTBs with either crosslinked or noncrosslinked trilayer amnion were able to withstand strain increases of at least 50%. Conclusion PTB repairs with commercial noncrosslinked amnion allograft membranes can withstand physiological strain and have comparable performance to repairs with human amnion, which has demonstrated efficacy in vivo. These results indicate the need for further testing of these membranes using in vivo animal model repairs. [ABSTRACT FROM AUTHOR]

The number of incidents worldwide where pile tip damage has occurred during driving has accelerated following the growth of the offshore wind sector, and the expansion into areas with increased risk of embedded boulders or partially weathered soft rocks. The process involving pile–boulder–soil contact can be simulated with advanced three-dimensional (3D) large-deformation dynamic coupled Eulerian–Lagrangian (CEL) finite-element (FE) analysis. However, analyses of this nature are highly time-consuming and computationally expensive. The objective of the paper is to develop a generic framework whereby the potential for denting by a boulder can be assessed a priori. The study encompasses four main components to determine the magnitude of force necessary to create plastic damage of the pile tip and what combination of boulders and soil might generate such reactions during pile installation: (a) a parametric 3D FE structural denting study; (b) a parametric boulder–soil 3D CEL study, where prescribed displacements were applied to the surface of boulders embedded in sand; (c) a range of pile–boulder–soil 3D CEL analyses where a deformable pile and different boulder–soil combinations were simulated; and (d) centrifuge model tests involving tip damage from boulders. Simple relationships and charts have been established from the numerical studies and validated from experimental work. [ABSTRACT FROM AUTHOR]

Background: In the last decade, tissue‐engineering strategies for regenerating the temporomandibular joint (TMJ) have been investigated. This may be a promising strategy for the minimally invasive restoration of joint integrity. Objectives: To evaluate whether dental pulp stem cells (DPSCs) loaded in a light‐occured hydrogel made of gelatin methacryloyl (GelMA) enhance the regeneration of osteochondral defects in the rabbit TMJ. Materials and Methods: Defects were filled with GelMA alone (control group; n = 4) or filled with GelMA loaded with rabbit DPSCs (experimental group; n = 4), In one group, the TMJ capsule was opened without creating a defect (sham group; n = 2). The following micro‐CT parameters were analysed: bone volume to total volume ratio (BV/TV%) and bone mineral density (BMD). Histological evaluation was performed to assess cartilage regeneration features. A semi‐quantitative scoring system was also used to evaluate the defects. Results: All groups had no statistical difference regarding the micro‐CT parameters. The highest mean healing score was found for the experimental group. After 4 weeks, there were no signs of hydrogel in either group or no signs of inflammation in the adjacent tissues. The tissue formed in the defect was dense fibrous connective tissue. Conclusion: Adding DPSCs to GelMA did not provide a regenerative enhancement in TMJ osteochondral defects. This resulted in similar micro‐CT parameters after 4 weeks of healing, with improved signs of subchondral bone regeneration but no cartilage regeneration. [ABSTRACT FROM AUTHOR]

Periprosthetic joint infections occur in about 2% of patients who undergo primary total joint arthroplasty, a procedure performed over 1 million times in the United States. The gold standard of treatment is a two‐stage revision. This study aimed to establish a two‐stage procedure in a preclinical small animal model (rat) to test and compare the efficacy of an antibiotic‐eluting material in managing infection. Joint replacement was simulated by transchondylarly implanting a polyethylene (PE) plug into the distal femur and a titanium screw in the proximal tibia. Methicillin‐sensitive Staphylococcus aureus (MSSA) 108 CFU/mL was injected into the tibial canal and the joint space before wound closure. The control groups were killed on postoperative day (POD) 18 (n = 12) and on POD 42 (n = 4) to assess both early and later‐stage outcomes in the control group. The test group underwent revision surgery on POD 18 for treatment using gentamicin‐eluting polyethylene (GPE, n = 4) and was observed until POD 42 to evaluate the efficacy of treatment. Our results showed that the bone loss for the treatment group receiving GPE was significantly less than that of the control (p < 0.05), which was supported by the histology images and an AI‐tool assisted infection rate evaluation. Gait metrics duty factor imbalance and hindlimb temporal symmetry were significantly different between the treatment and control groups on Day 42. This animal model was feasible for evaluating treatments for peri‐prosthetic joint infections (PJI) with a revision surgery and specifically that revision surgery and local antibiotic treatment largely hindered the peri‐prosthetic bone loss. Statement of clinical significance: This revision model of peri‐prosthetic infection has the potential of comparatively evaluating prophylaxis and treatment strategies and devices. Antibiotic‐eluting UHMWPE is devised as at tool in treating PJI while providing weight bearing and joint space preservation. [ABSTRACT FROM AUTHOR]

Background: Despite therapeutic advances, once a cancer has metastasized to the bone, it represents a highly morbid and lethal disease. One third of patients with advanced clear cell renal cell carcinoma (ccRCC) present with bone metastasis at the time of diagnosis. However, the bone metastatic niche in humans, including the immune and stromal microenvironments, has not been well-defined, hindering progress towards identification of therapeutic targets. Methods: We collected fresh patient samples and performed single-cell transcriptomic profiling of solid metastatic tissue (Bone Met), liquid bone marrow at the vertebral level of spinal cord compression (Involved), and liquid bone marrow from a different vertebral body distant from the tumor site but within the surgical field (Distal), as well as bone marrow from patients undergoing hip replacement surgery (Benign). In addition, we incorporated single-cell data from primary ccRCC tumors (ccRCC Primary) for comparative analysis. Results: The bone marrow of metastatic patients is immune-suppressive, featuring increased, exhausted CD8 + cytotoxic T cells, T regulatory cells, and tumor-associated macrophages (TAM) with distinct transcriptional states in metastatic lesions. Bone marrow stroma from tumor samples demonstrated a tumor-associated mesenchymal stromal cell population (TA-MSC) that appears to be supportive of epithelial-to mesenchymal transition (EMT), bone remodeling, and a cancer-associated fibroblast (CAFs) phenotype. This stromal subset is associated with poor progression-free and overall survival and also markedly upregulates bone remodeling through the dysregulation of RANK/RANKL/OPG signaling activity in bone cells, ultimately leading to bone resorption. Conclusions: These results provide a comprehensive analysis of the bone marrow niche in the setting of human metastatic cancer and highlight potential therapeutic targets for both cell populations and communication channels. [ABSTRACT FROM AUTHOR]

The risk posed by seabed instability is of increasing significance as offshore activities including oil and gas developments continue to expand in this century. Many studies have considered runout of debris flows resulting from submarine landslides and potential impact on offshore infrastructure. However, initiation of slab failure resulting from shear band propagation (SBP) at the onset of a landslide has received less attention, although it is of key importance for estimating the scale and consequences of landslides. The present paper explores arrest of SBP as well as global slab failure above the shear band. The complete evolution of a submarine landslide from shear band initiation, propagation, slab failure, and arrest of SBP is observed through large-deformation finite element (LDFE) modelling. Governing equations for both dynamic and quasi-static SBP are established and solved, with results showing good agreement with the LDFE results. Lower limits for the final shear band length and for global slab failure are proposed for cases with high strain-rate dependency of shear strength, where shear band propagation is quasi-static; upper limits are proposed for cases without rate effects where the behaviour is dynamic. Key words: failure, landslides, shear strength, slopes, offshore engineering. Les risques poses par l'instabilite des fonds marins sont de plus en plus importants, car les activites d'exploitation de mer, y compris les developpements petroliers et gaziers, continuent de prendre de l'ampleur au cours de ce siecle. De nombreuses etudes ont pris en compte le debordement des coulees de debris resultant des glissements sous-marins et l'impact potentiel sur les infrastructures d'exploitation de mer. Cependant, l'initiation de la rupture de la plaque resultant de la propagation de la bande de cisaillement (PBC) au debut d'un glissement a recu moins d'attention, bien qu'elle soit d'une importance capitale pour estimer l'echelle et les consequences des glissements. Le present article explore l'arret de la PBC ainsi que la rupture de la plaque globale au-dessus de la bande de cisaillement. L'evolution complete d'un glissement sous-marin a partir de l'initiation de la bande de cisaillement, de la propagation, de la rupture de la plaque et de l'arret de la SBP est observee grace a une modelisation par elements finis de grandes deformations (<< LDFE >>). Les equations determinantes pour la PBC dynamiques et quasi statiques sont etablies et resolues, les resultats montrant un bon accord avec les resultats par LDFE. Des limites inferieures pour la longueur finale de la bande de cisaillement et pour la rupture globale de la plaque sont proposees pour les cas ou la vitesse de deformation depend fortement de la resistance au cisaillement, ou la propagation de la bande de cisaillement est quasi statique; des limites superieures sont proposees pour les cas sans effets de taux lorsque le comportement est dynamique. [Traduit par la Redaction] Mots-cles: echec, glissements, resistance au cisaillement, pentes, ingenierie d'exploitation de mer., Introduction Instability of submarine or subaqueous slopes is ubiquitous throughout the world, including much studied examples such as the giant Storegga landslide that occurred 8200 years ago in the North [...]

The touchdown zones of steel catenary risers and lazy wave risers are fatigue hotspots, where the risers interact continuously with the seabed due to hydrodynamic loading exerted on the host vessel. The whole-life interactions can range from small-amplitude daily motion cycles to motions that involve large-amplitude cyclic interaction with the seabed during storm events. A key design challenge that affects the fatigue life of these risers is the accurate modelling of the evolution of the riser–soil stiffness, throughout the whole life of the riser and for different soil conditions, including overconsolidated conditions, which may occur due to the geological history, ageing or biochemical processes of the sediments. This paper describes centrifuge model pipe tests simulating whole-life riser–soil interaction in normally consolidated and uniform overconsolidated clay samples, under successive sequences of cyclic motions. Results confirm that the whole-life soil stiffness evolution depends strongly on cyclic amplitudes, with reconsolidation-induced soil stiffness recovery after heavy remoulding, and is also influenced by the soil overconsolidation ratio, with a reduced tendency for soil hardening at higher soil overconsolidation ratios. This study provides insights into the relevant cyclic soil stiffness to consider when assessing the whole-life design of risers interacting with overconsolidated seabed sediments. [ABSTRACT FROM AUTHOR]

Autonomization is a physiological process allowing a flap to develop neo-vascularization from the reconstructed wound bed. This phenomenon has been used since the early application of flap surgeries but still remains poorly understood. Reconstructive strategies have greatly evolved since, and fasciocutaneous flaps have progressively replaced muscle-based reconstructions, ensuring better functional outcomes with great reliability. However, plastic surgeons still encounter challenges in complex cases where conventional flap reconstruction reaches its limitations. Furthermore, emerging bioengineering applications, such as decellularized scaffolds allowing a complex extracellular matrix to be repopulated with autologous cells, also face the complexity of revascularization. The objective of this article is to gather evidence of autonomization phenomena. A systematic review of flap autonomization is then performed to document the minimum delay allowing this process. Finally, past and potential applications in bio- and tissue-engineering approaches are discussed, highlighting the potential for in vivo revascularization of acellular scaffolds. [ABSTRACT FROM AUTHOR]

Machine perfusion has developed rapidly since its first use in solid organ transplantation. Likewise, reconstructive surgery has kept pace, and ex vivo perfusion appears as a new trend in vascularized composite allotransplants preservation. In autologous reconstruction, fasciocutaneous flaps are now the gold standard due to their low morbidity (muscle sparing) and favorable functional and cosmetic results. However, failures still occasionally arise due to difficulties encountered with the vessels during free flap transfer. The development of machine perfusion procedures would make it possible to temporarily substitute or even avoid microsurgical anastomoses in certain complex cases. We performed oxygenated acellular sub-normothermic perfusions of fasciocutaneous flaps for 24 and 48 h in a porcine model and compared continuous and intermittent perfusion regimens. The monitored metrics included vascular resistance, edema, arteriovenous oxygen gas differentials, and metabolic parameters. A final histological assessment was performed. Porcine flaps which underwent successful oxygenated perfusion showed minimal or no signs of cell necrosis at the end of the perfusion. Intermittent perfusion allowed overall better results to be obtained at 24 h and extended perfusion duration. This work provides a strong foundation for further research and could lead to new and reliable reconstructive techniques. [ABSTRACT FROM AUTHOR]

Pile drivability predictions require information on the pile geometry, impact hammer, and the soil resistance to driving (SRD). Current SRD prediction methods are based on databases of long slender piles from the oil and gas industry and new, robust, and adaptable methods are required to predict SRD for current offshore pile geometries. This paper describes an optimization framework to update uncertain model parameters in existing axial static design methods to calibrate SRD. The approach is demonstrated using a case study from a German offshore wind site. The optimization process is undertaken using a robust Bayesian approach to dynamically update uncertain variables during driving to improve simulations. The existing method is shown to perform well for piles with geometries that reflect the underlying database such that only minimal optimization is required. For larger diameter piles, relative to the prior best estimate, optimized results are shown to provide significant improvements in the mean calculations and associated variance of pile drivability as more data is acquired. The optimized parameters can be used to predict SRD for similar piles in analogous ground conditions. The demonstrated framework is adaptable and can be used to develop site-specific calibrations and advance new SRD methods where large pile driving data sets are available. [ABSTRACT FROM AUTHOR]