Breakage Events Research Articles

Posterior spinal fusion versus vertebral body tethering for paediatric scoliosis: a meta-analysis of comparative studies.

Posterior spinal fusion (PSF) is currently the gold standard technique for surgical correction of scoliosis however, there is a growing interest in non-fusion techniques like vertebral body tethering (VBT). The aim of this study is to compare surgical outcomes between PSF and VBT. This systematic review was performed as per the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Guidelines with a search of the following databases to identify all comparative studies: MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL). A total of 11 comparative studies with 1112 patients were included. PSF offered significantly greater percentage coronal curve correction postoperatively (P = 0.0001) and at 2years (P < 0.00001). Time to revision (P = 0.03), number of instrumented levels (P < 0.0001), estimated blood loss (EBL) (P = 0.001), operation duration (OD) (P < 0.00001) and postoperative shoulder height difference (P < 0.00001) were significantly greater in the PSF group. Odds of unplanned surgical revisions were lower in the PSF group (P < 0.0001). Secondary outcome data showed that VBT patients had significantly lower preoperative cobb angles (P < 0.00001), a younger age at surgery (P = 0.002), less postoperative pain (P = 0.002) and loweropioid consumption (P = 0.02). VBT tether breakage events were reported at rates of 13-23%. VBT also offered faster return to sports and greater lumbar flexibility. No significant difference was seen in length of hospital stay (P < 0.05). PSF and VBT are viable treatment options with different pros and cons. Choice of treatment should consider individual patient characteristics and daily requirements.

Dynamic mechanical analysis of alginate/gellan hydrogels under controlled conditions relevant to environmentally sensitive applications.

Hydrogels are natural/synthetic polymer-based materials with a large percentage of water content, usually above 80%, and are suitable for many application fields such as wearable sensors, biomedicine, cosmetics, agriculture, etc. However, their performance is susceptible to environmental changes in temperature, relative humidity, and mechanical deformation due to their aqueous and soft nature. We investigate the mechanical response of both filled and unfilled alginate/gellan hydrogels using a combined axial-torsional rheometric approach with cylindrical samples of large length/diameter ratio under controlled temperature and relative humidity. Dynamic Mechanical Analysis (DMA) is performed on the same specimen in both torsion and extension under identical experimental conditions. This rheometric approach ensures consistent initial and boundary conditions, which are essential for a reliable estimation of viscoelastic moduli G* and E*, and their dependence on temperature, frequency, and relative humidity. Our findings indicate that humidity critically affects the mechanical response of the material due to sample volume shrinkage, necessitating corrections to the viscoelastic moduli. We also find temperature plays a role only at low/medium relative humidity values. The inclusion of fillers leads to a modest increase in the elasticity of the hydrogel, probably due to restricted water diffusion out of the sample. In connection with the latest, unfilled samples in breaking tests present only slippage due to twist-induced surface water excess, opposite to breakage events shown by filled samples, probably linked to restricted water diffusion.

DEM simulation of an impact crusher using the fast-cutting breakage model

The impact crusher that exploits impact rather than pressure to break down materials has been widely used in the mineral industry. To further improve its performance in material crushing, numerical simulation capable of providing a deeper insight into the complicated dynamics of feed materials than experimental study has emerged as a promising tool. However, the field of the accurate prediction of product quality and explicit simulation of breakage events inside an industrial-scale crusher remains underexplored on account of the absence of a robust breakage model and heavy computational cost. In this study, a numerical investigation of an industrial-scale crusher using the fast-cutting breakage model is conducted within the DEM (Discrete Element Method) framework. The accuracy of the breakage simulation is quantitatively validated by comparing the predicted results with the measurements from actual production. Furthermore, the influence of operating conditions including the rotation speed of the rotor and the feeding rate on the interested parameters, i.e., the power consumption of the equipment, the size distribution of the products, and the impact-induced wear is investigated comprehensively. The results illustrate that (i) the size of the product increases with the rotor speed until a critical value, after which a further increase in rotor speed will exert no significant influence on the size distribution; (ii) The feeding rate is not a critical operating condition that largely determines the fineness of the product and the efficiency of the equipment almost remain stable under a certain range of feeding rates; (iii) The wear of the devices concentrates on the rotor and the impact plates, and the distribution of the wear exhibits different characteristics in different parts, caused by the complex collision between the particles and the devices.

An analytic approach for nonlinear collisional fragmentation model arising in bubble column

The phenomenon of coagulation and breakage of particles plays a pivotal role in diverse fields. It aids in tracking the development of aerosols and granules in the pharmaceutical sector, coagulation or breakage of droplets in chemical engineering, understanding blood clotting mechanisms in biology, and facilitating cheese production through the action of enzymes within the dairy industry. A significant portion of research in this direction concentrates on coagulation or linear breakage processes. In the case of linear case, bubble particles break down due to inherent stresses or specific conditions of the breakage event. However, in many practical situations, particle division is primarily due to forces exerted during collisions between particles, necessitating an approach that accounts for nonlinear collisional breakage. Despite its critical role in a wide array of engineering and physical operations, the study of this nonlinear fragmentation phenomenon has not been extensively pursued. This article introduces an innovative semi-analytical method that leverages the beyond linear use of equation superposition function to address the nonlinear integro-partial differential model of collisional breakage population balance. This approach is versatile, allowing for the resolution of both linear/nonlinear equations while sidestepping the complexities associated with discretization of domain. To assess the precision of this method, we conduct a thorough convergence analysis. This process utilizes the principle of contractive mapping in the Banach space, a globally recognized strategy for verifying convergence. We explore a variety of kernel parameters associated with collisional kernels, alongside breakage and initial distribution functions, to derive novel iterative solutions. Comparing our findings with those obtained through the finite volume method regarding number density functions and their integral moments, we demonstrate the reliability and accuracy of our approach. The consistency and correctness of our method are further validated by depicting the errors between the exact and approximated solutions in graphical and tabular formats.

Molecular Cytogenetic Characterization of Rare but Repeatedly Observed Inversions in German Population

Introduction: The term inversion refers to an aberration caused by two breakage and fusion events found in one or both arms of a chromosome. The presence of such aberrations can but must not be associated with infertility or unbalanced products of conception. Normally, inversions are not associated with phenotypic alterations for the carrier. Despite the fact that most such inversions are de novo and unique, recurrent breakpoints have also been reported. Methods: Here two recurrent paracentric inversions in the long arm of chromosomes 11 and 12 and a pericentric one in chromosome 10 were studied in at least 10 unrelated (infertile) patients, each. Breakpoints were narrowed down by fluorescence in situ hybridization applying locus-specific bacterial artificial chromosome-derived probes. Results: Molecular cytogenetically identical breakpoints could be characterized for all three studied inversions. Pericentric inversion inv(10)(p11.21q21.2), previously reported to be of single origin and distributed mainly in Northern Europe, could be found to be present all over Germany, too. In the studied cases with paracentric inversion inv(11)(q21q23.3), recurrent breakpoints were found in all parts of Germany, as well; however, additional 2 cases with slightly different breakpoints were characterized besides. Most interestingly, inversion inv(12)(q14.1∼14.2q24.11∼24.13) had always the same recurrent breakpoints and presented an exclusive occurrence in North-Western part of Germany. Conclusion: Overall, (at least) three different cytogenetically detectable recurrent inversions were characterized here. This highlights that such events may be more frequent in human population than yet suggested. Accordingly, such events might even spread in (middle European) human population. Specific impact on reproduction and fitness of inversion carriers characterized here seems to be negligible. Nonetheless, such recurrent rearrangements need more attention as they may provide valuable information for genetic counseling in future.

Characterizing damage evolution in fiber reinforced composites using in-situ X-ray computed tomography, deep machine learning and digital volume correlation (DVC)

In-situ X-ray computed tomography (CT) techniques enable to examine microstructural evolution of composite materials continuously and nondestructively under loading for better understanding the initiation and propagation of microscopic damages. This study explores the tensile damage behavior of notched woven carbon/epoxy composites under successive loading process. Since the image contrast of different composite material phases is normally low and conventional image segmentation techniques are hard to identify microstructures and defects in different directions distinctively, a U-Net image segmentation model based on deep machine learning algorithms is employed to characterize microstructures and material damages precisely and consistently. Digital volume correlation (DVC) approach is proposed here tocharacterize the three-dimensional (3D) deformation fields of carbon/epoxy composites at different loading steps, and the DVC results are used to predict location of damage initiation and propagation. It is found that the damage modes of notched carbon/epoxy composites mainly include fiber breakage, longitudinal cracks in warp fiber tows, and transverse cracks in weft fiber tows. The individual fiber breakage occurs in warp fiber tows at the intermediate loading level, and longitudinal and transverse cracks appear in further loading levels. Longitudinal cracks and fiber breakage events take place in a region tangent to the notch tip and exhibit a strong interaction. The development of longitudinal cracks promotes the initiation and propagation of transverse cracks. In addition, the strain concentration regions in 3D deformation fields match well with the microscopic cracks segmented by the U-Net deep learning model. This study demonstrated that the integration of X-ray computed tomography, digital volume correlation and image semantic segmentation enables to identify damage initiation, evolution, extent and mechanism.

Numerical Analysis of Dynamic Response in Large Caissons during Wet-towing after Cable Breakage

Variable and complex marine environmental loads combined with wave resistance and the insufficient controllability of large caisson structures pose serious challenges during maritime towing. Cable breakage events are common, and improper behaviors could give rise to a variety of accidents. This work explored the dynamic responses of large caisson structures following towing cable breakage under irregular waves combined with harsh currents. Two types of cable breakage, i.e., main bridle and towing bridle breakage, were taken into account. Four potential wave–current combinations were assumed for each situation according to direction. The obtained results show that drag rope breakage could give rise to lateral shifts in the structure, which can become a serious condition when exposed to angled waves. Additionally, following breakage, significant force fluctuations took place in the remaining intact cables. For main cable breakage, both lateral and backward displacements were observed in the structure, which gradually entered a ‘flowing with the wave’ state. Furthermore, under the two abovementioned cable breakage conditions, the structure air gap consistently exceeded 2.3 m, ignoring the possibility of a wave slamming event.

Degradation of plastic materials in the marine environment: A mussel farm as a case study for the development of alternative mussel nets

Currently, mussel farming uses of traditional plastic nets that accumulate on beaches and on the seabed in the event of breakage and accidental dispersion, contributing to the marine litter issue. An attempt is being made to replace the polypropylene nets with alternative materials to make the aquaculture full production cycle more sustainable. However, alternative materials need to be characterised both functionally and environmentally. This article describes a characterisation study in which plastic materials were exposed for approximately three years to the marine environment in a bay dedicated to mussel farming to provide data on the degradation behaviour of the selected polymers for eco-design purposes. Samples of the different materials, in the form of 3-mm thick dumbbells, were placed on the seabed at a depth of 12 m and in the water column at 2 m below the sea surface. At different time periods (after 6, 15, 24, 32 months), the samples were recovered, their mass and thickness were measured, and the mechanical properties were characterised. The results lead to the identification of some materials as sufficiently resistant to deterioration and therefore possible candidates for the application. Other materials generally used to make bags and films showed a very fast degradation and therefore do not seem to meet the performance requirements for mussel farming. The methodology used in this study seems suitable for conducting long-term exposure tests on locations of interest and collecting specific data for eco-design purposes before the application of the product on the markets.

Generating Molecular Fragmentation Graphs with Autoregressive Neural Networks.

The accurate prediction of tandem mass spectra from molecular structures has the potential to unlock new metabolomic discoveries by augmenting the community's libraries of experimental reference standards. Cheminformatic spectrum prediction strategies use a "bond-breaking" framework to iteratively simulate mass spectrum fragmentations, but these methods are (a) slow due to the need to exhaustively and combinatorially break molecules and (b) inaccurate as they often rely upon heuristics to predict the intensity of each resulting fragment; neural network alternatives mitigate computational cost but are black-box and not inherently more accurate. We introduce a physically grounded neural approach that learns to predict each breakage event and score the most relevant subset of molecular fragments quickly and accurately. We evaluate our model by predicting spectra from both public and private standard libraries, demonstrating that our hybrid approach offers state-of-the-art prediction accuracy, improved metabolite identification from a database of candidates, and higher interpretability when compared to previous breakage methods and black-box neural networks. The grounding of our approach in physical fragmentation events shows especially great promise for elucidating natural product molecules with more complex scaffolds.

Dicentric chromosomes are resolved through breakage and repair at their centromeres

Chromosomes with two centromeres provide a unique opportunity to study chromosome breakage and DNA repair using completely endogenous cellular machinery. Using a conditional transcriptional promoter to control the second centromere, we are able to activate the dicentric chromosome and follow the appearance of DNA repair products. We find that the rate of appearance of DNA repair products resulting from homology-based mechanisms exceeds the expected rate based on their limited centromere homology (340 bp) and distance from one another (up to 46.3 kb). In order to identify whether DNA breaks originate in the centromere, we introduced 12 single-nucleotide polymorphisms (SNPs) into one of the centromeres. Analysis of the distribution of SNPs in the recombinant centromeres reveals that recombination was initiated with about equal frequency within the conserved centromere DNA elements CDEII and CDEIII of the two centromeres. The conversion tracts range from about 50 bp to the full length of the homology between the two centromeres (340 bp). Breakage and repair events within and between the centromeres can account for the efficiency and distribution of DNA repair products. We propose that in addition to providing a site for kinetochore assembly, the centromere may be a point of stress relief in the face of genomic perturbations.

Stress stateofa composite tractive element with cable rigidity variable over length considering bending on a drum with curved generatrix

Purpose. Establishment of dependencies for parameters of a stress-strain state of a composite tractive element taking into account bending of a rope with cable rigidity variable over length on a drum with a curved generatrix. Research methodology. Development of a method for calculating the influence of a complex of factors on a stress-strain state of a rope by constructing and solving a model of a stress-strain state of a composite tractive element with cable tensile rigidity variable over length, cable base breakages and a non-cylindrical drum shape, using the methods of mechanics of layered composite materials with soft and hard layers. Findings. Analytical dependencies are obtained in a closed form and allow determining the maximum quantitative indicators of a stress-strain state of a rope of a combined structure with a broken cable, rigidity different from the main cables and variable along rope length in a straight rope part and in a part of interaction with a curved drum of a hoisting machine. Analytical dependencies are established for determining the maximum angles of rubber shear between cables, which allows determining the dangerous tangential stresses in a tractive element for cases of flat rope tension, rope bending on a convex drum, and bending on a convex drum of a rope with cables of reduced tensile rigidity. The results of solving the problem of determining the distribution of forces in a rope with cables of different rigidity by the developed method absolutely coincide with the only possible distribution of forces in a sample of three cables, which allows considering the developed algorithm reliable to describe the mechanism of redistribution of forces between cables with different tensile rigidity, including in the event of cable breakage, and the obtained results are reliable. Scientific novelty. A method of calculating the influence of a complex of factors on a stress-strain state of a rope is developed. The dependencies of parameters of a stress-strain state of a composite tractive element are established, taking into account rope bending, which has cable base breakages and cable rigidity variable over length, on a drum with a curved generatrix. Practical significance. A method for determining the indicators of a stress-strain state of a composite tractive element, which has cable base breakages and cable rigidity variable over length, including for bending on a non-cylindrical drum, is developed. This makes it possible to increase the operational safety of a composite tractive element in hoisting and transporting machines, in particular at significant hoisting heights, and also contributes to justifying the use of a rope design as a stay rope in capital structures.

Novel experimental data-driven bubble breakage model for universal application in Euler-Lagrange multiphase frameworks

An experimental data driven model for the prediction of bubble breakage in gas–liquid multiphase reactors was developed which fulfills requirements of the Euler-Lagrangian (EL) framework for the analysis of individual bubbles. The critical Weber number (Wecrit) serves as the breakage criterion in combination with the minimum time between two consecutive breakage events. Wecrit indicates when the hydrodynamic forces acting on an individual bubble surmount its surface tension. Once the threshold is passed a binary bubble breakup event occurs, which results in the formation of daughter bubbles assigned to an M−shaped daughter size distribution (DSD). Optimum Wecrit values were obtained by minimizing the difference between simulated and measured Sauter mean diameters d32. The latter were derived from bubble size distributions (BSDs) measurements that cover about 11 – 89 W m−3 power inputs. Using deionized water and a minimum timespan of 30 ms between two consecutive breakages Wecrit = 6.1 was determined. To extend the scope of the model, characteristic media compositions for so-called syngas fermentations with Clostridium ljungdahlii were investigated. To match surface tension and viscosity with those of fresh medium (FM) and late phase medium (LPM), two aqueous solutions containing sodium dodecyl sulfate (SDS) and glycerol were prepared. Notably, the breakage model managed to well predict the impact of altered fluid properties of FM and LPM without requiring further calibration. The sum of Sauter diameter deviation between simulations and experiments was only 0.21 and 0.40 mm for FM and LPM, respectively.

Centromere: A Trojan horse for genome stability

Centromeres play a key role in the maintenance of genome stability to prevent carcinogenesis and diseases. They are specialized chromosome loci essential to ensure faithful transmission of genomic information across cell generations by mediating the interaction with spindle microtubules. Nonetheless, while fulfilling these essential roles, their distinct repetitive composition and susceptibility to mechanical stresses during cell division render them susceptible to breakage events. In this review, we delve into the present understanding of the underlying causes of centromere fragility, from the mechanisms governing its DNA replication and repair, to the pathways acting to counteract potential challenges. We propose that the centromere represents a “Trojan horse” exerting vital functions that, at the same time, potentially threatens whole genome stability.

Impact of Continuous Cable-Strut Joints on the Anti-Progressive-Collapse Performance of Suspended-Dome Structures

In suspended-dome structures, cable-strut joints can be categorized into discontinuous joints and continuous joints. In calculations, the discontinuous joints can be treated as hinge joints. However, in the event of a cable breakage, the continuous joints might experience slip and detachment phenomena. Simplifying continuous cable-strut joints as hinge joints for calculation purposes can result in a significant discrepancy from the actual load-bearing state of the continuous joints. In fact, under the scenario of cable rupture, the continuous cable-strut joints might undergo slip and detachment. This could influence the formation of new tension paths within the cable support system, thereby affecting the anti-collapse performance of the suspended-dome structure. Therefore, this paper investigates the influence of the slippage and detachment of continuous cable-strut joints on the anti-progressive collapse performance of suspended-dome structures through joint tests, numerical simulations, and theoretical analyses. Firstly, two cable-strut joint test models were constructed. Apart from the difference that one uses a discontinuous cable-strut joint and the other a continuous cable-strut joint, all other conditions were kept identical. Research was conducted on the hoop cable failure test. The results indicate that the slippage and detachment of continuous joints hinder the formation of new tension paths in the lower cable-strut system. Structures using continuous cable-strut joints have lower anti-collapse capabilities compared to those using discontinuous cable-strut joints. Secondly, a simplified numerical simulation algorithm for cable-strut joints’ slippage and detachment is proposed. This algorithm only considers the support of struts to the upper structure and uses an Abaqus subroutine to achieve an equivalent simulation of the slippage and detachment phenomena of continuous joints during the finite element computation process. Then, using this algorithm, a progressive collapse analysis of suspended domes using continuous cable-strut joints was carried out. It was found that for suspended domes with continuous cable-strut joints, the slippage and detachment of the cable-strut joints are extremely detrimental to forming new tension paths, making the structure more susceptible to a progressive collapse. Lastly, using the resistance index, a quantitative analysis was conducted on the anti-collapse carrying capacity of suspended domes using both continuous and discontinuous cable-strut joints.

Testing a Method Based on an Improved UNet and Skeleton Thinning Algorithm to Obtain Branch Phenotypes of Tall and Valuable Trees Using Abies beshanzuensis as the Research Sample.

Sudden changes in the morphological characteristics of trees are closely related to plant health, and automated phenotypic measurements can help improve the efficiency of plant health monitoring, and thus aid in the conservation of old and valuable tress. The irregular distribution of branches and the influence of the natural environment make it very difficult to monitor the status of branches in the field. In order to solve the problem of branch phenotype monitoring of tall and valuable plants in the field environment, this paper proposes an improved UNet model to achieve accurate extraction of trunk and branches. This paper also proposes an algorithm that can measure the branch length and inclination angle by using the main trunk and branches separated in the previous stage, finding the skeleton line of a single branch via digital image morphological processing and the Zhang-Suen thinning algorithm, obtaining the number of pixel points as the branch length, and then using Euclidean distance to fit a straight line to calculate the inclination angle of each branch. These were carried out in order to monitor the change in branch length and inclination angle and to determine whether plant branch breakage or external stress events had occurred. We evaluated the method on video images of Abies beshanzuensis, and the experimental results showed that the present algorithm has more excellent performance at 94.30% MIoU as compared with other target segmentation algorithms. The coefficient of determination (R2) is higher than 0.89 for the calculation of the branch length and inclination angle. In summary, the algorithm proposed in this paper can effectively segment the branches of tall plants and measure their length and inclination angle in a field environment, thus providing an effective method to monitor the health of valuable plants.

Data-driven ANN approach for binary agglomerate collisions including breakage and agglomeration

The present contribution is a follow-up of a recently conducted study to derive a data-driven model for the breakage of agglomerates by wall impacts. This time the collision-induced breakage of agglomerates and concurrently occurring particle agglomeration processes are considered in order to derive a model for Euler–Lagrange methods, in which agglomerates are represented by effective spheres. Although the physical problem is more challenging due to an increased number of influencing parameters, the strategy followed is very similar. In a first step extensive discrete element simulations are carried out to study a variety of binary inter-agglomerate collision scenarios. That includes different collision angles, collision velocities, agglomerate sizes and powders. The resulting extensive database accounts for back-bouncing, agglomeration and breakage events. Subsequently, the collision database is used for training artificial neural networks to predict the post-collision number of arising entities, their size distributions and their velocities. Finally, it is shown how the arising data-driven model can be incorporated into the Euler–Lagrange framework to be used in future studies for efficient computations of flows with high mass loadings.

Real-World Outcomes in USA using DBS Systems with Directionality and Multiple Independent Current Control (P5-11.017)

Real-World Outcomes in USA using DBS Systems with Directionality and Multiple Independent Current Control (P5-11.017)

Transferring Bubble Breakage Models Tailored for Euler-Euler Approaches to Euler-Lagrange Simulations

Most bubble breakage models have been developed for multiphase simulations using Euler-Euler (EE) approaches. Commonly, they are linked with population balance models (PBM) and are validated by making use of Reynolds-averaged Navier-Stokes (RANS) turbulence models. The latter, however, may be replaced by alternate approaches such as Large Eddy simulations (LES) that play a pivotal role in current developments based on lattice Boltzmann (LBM) technologies. Consequently, this study investigates the possibility of transferring promising bubble breakage models from the EE framework into Euler-Lagrange (EL) settings aiming to perform LES. Using our own model, it was possible to reproduce similar bubble size distributions (BSDs) for EL and EE simulations. Therefore, the critical Weber (Wecrit) number served as a threshold value for the occurrence of bubble breakage events. Wecrit depended on the bubble daughter size distribution (DSD) and a set minimum time between two consecutive bubble breakage events. The commercial frameworks Ansys Fluent and M-Star were applied for EE and EL simulations, respectively. The latter enabled the implementation of LES, i.e., the use of a turbulence model with non-time averaged entities. By properly choosing Wecrit, it was possible to successfully transfer two commonly applied bubble breakage models from EE to EL. Based on the mechanism of bubble breakage, Wecrit values of 7 and 11 were determined, respectively. Optimum Wecrit were identified as fitting the shape of DSDs, as this turned out to be a key criterion for reaching optimum prediction quality. Optimum Wecrit values hold true for commonly applied operational conditions in aerated bioreactors, considering water as the matrix.

Fate and Exposure Assessment of Pb Leachate from Hypothetical Breakage Events of Perovskite Photovoltaic Modules.

Emerging lead halide perovskite (LHP) photovoltaics are undergoing intense research and development due to their outstanding efficiency and potential for low manufacturing costs that render them competitive with existing photovoltaic (PV) technologies. While today's efforts are focused on stability and scalability of LHPs, the toxicity of lead (Pb) remains a major challenge to their large-scale commercialization. Here, we present a screening-level, EPA-compliant model of fate and transport of Pb leachate in groundwater, soil, and air, following hypothetical catastrophic breakage of LHP PV modules in conceptual utility-scale sites. We estimated exposure point concentrations of Pb in each medium and found that most of the Pb is sequestered in soil. Exposure point concentrations of Pb from the perovskite film fell well below EPA maximum permissible limits in groundwater and air even upon catastrophic release from PV modules at large scales. Background Pb levels in soil can influence soil regulatory compliance, but the highest observed concentrations of perovskite-derived Pb would not exceed EPA limits under our assumptions. Nonetheless, regulatory limits are not definitive thresholds of safety, and the potential for increased bioavailability of perovskite-derived Pb may warrant additional toxicity assessment to further characterize public health risks.

Breakage Costs in Flexible Ureteroscopy: Digital vs. Fiberoptic Modalities

To compare the maintenance costs of digital flexible ureteroscopes (DFU) versus fiberoptic flexible ureteroscopes (FFU) to understand the long-term financial impact associated with breakage in a flexible ureteroscopy (f-URS) program. Data for breakage of FFU and DFU at an academic institution from 2019 to 2021 were obtained from our vendor (Karl Storz) and analyzed by month. Correlation test was used to evaluate significant differences in number of procedures, number of breakage events, breakage rates, and repair cost per month. Cumulative analyses were utilized to examine the number of procedures before failure (time to failure - TTF) and repair costs per procedure (RCpP). We performed a total of 2,154 f-URS, including 1,355 with FFU and 799 with DFU (P<.001). Although we found a higher number of breakage events in FFU (n=124) than DFU (n=73) (P<.001), the overall breakage rate was similar, 9.9% vs. 8.8%, respectively (P=0.86). On cumulative analysis, both modalities reached the same TTF plateau (11 cases) after 18 months. After 400 cases, the RCpP for DFU was 1.25 times higher than for FFU (P=0.04). Overall, we found no difference in overall scope breakage rates between DFU and FFU. Although there was no difference in TTF over time, at the beginning DFU displayed considerable higher durability, leading to lower RCpP. Furthermore, DFU's endurance leveled off to FFU over time, resulting in higher RCpP after 400 cases. This finding may be explained by the presence of renewed scopes after repair.