Perforation Pattern Research Articles

GEP-based models for estimating the elastic shear buckling and ultimate loads of cold-formed steel channels with staggered slotted web perforations in shear

Thermal bridging through cold-formed steel (CFS) channels can be substantially reduced by introducing staggered slots in the channels’ webs. The perforation size and pattern significantly affect the elastic shear buckling and ultimate loads of the channels in shear, which must be considered in the design. This paper proposes new models for accurate estimations of the shear buckling and ultimate loads derived from an extensive database by employing gene expression programming (GEP). The model constructions involve various dimensional parameters, types of boundary conditions, and the yield strength of the channels. The proposed GEP models, in the form of transparent mathematical expressions, provide reasonable prediction accuracy comparable to published descriptive equations. However, the GEP models are simpler than the existing equations and do not require additional advanced computations, as the existing equations do, to obtain the elastic shear buckling and ultimate shear loads. LRFD resistance and ASD safety factors for the proposed GEP model were determined in accordance with AISI S100-16 w/S2-20. Based on the presented information, the GEP models are recommended for estimating the elastic shear buckling and ultimate loads of CFS channels with staggered slotted web perforations in shear.

건축 파사드의 디지털 패턴 디자인 유형에 대한 감성 특성 - 밴 팰(Ben Pell)의 파사드 패턴 유형을 중심으로 -

Pattern is a visually important element in designing an architectural facade. The digital pattern design such as a facade is deeply related to aesthetic characteristics in architecture and interior design. However, the lack of research on a systematic design process for digitalized pattern design such a facade, poses a problem for designers. This research provides emotional characteristics on five types of architectural facade pattern: applied, perforated, layered, cast, and tiled. The analysis is based on an existing study that briefly analyzed their emotional characteristics, and this is combined with the results of other research on emotional characteristics of applied and perforated patterns. First, reviewing previous research reveals the reasons for selecting façade pattern types classified by Ben Pell and determines their classification criteria, the definitions, the general characteristics and the representative projects of the five types of architectural facade. Second, the survey method from existing research is used to establish targets, method, and analysis. Third, general information of survey respondents is analyzed in terms of gender, age, education, occupation, and experience. Results represent emotional characteristics by case and by type of digital pattern design of architectural facade and reveal a correlation between determined emotional characteristics by type and by case. After deriving their correlations, this study finally determines the emotional characteristics by type and case. Emotional responses are then presented by type and case. Fourth, the results are compared and analyzed with those of existing research. The results in the emotional characteristics show that the applied and layered patterns are continuous and discontinuous-continuous, respectively, the perforated pattern is irregular and irregular-regular, and the cast and tiled patterns are regular and irregular-regular, respectively. In the comparison of the average value by facade pattern design type, based on the results and as a design concept, a continuous continuity is more suitable for the layered pattern than the applied pattern, a regular regularity is more appreciated for the cast pattern than the tiled pattern, and an irregular regularity is good for designing the perforated pattern.

Using Mechanical Metamaterials in Guitar Top Plates: A Numerical Study

It has recently been shown that the mechanical properties of thin, rectangular wooden plates can be tuned by carving them with specific patterns of perforations, effectively realising a 2D wooden mechanical metamaterial. Such a material is of great interest for the construction of musical instruments, as it could allow a new degree of creative control for makers. Furthermore, issues with the shrinking supplies of tone-woods could be alleviated as wood samples that don not meet the desired requirements could simply be altered, instead of being discarded. In this work, we study the effect of the use of these metamaterials in the soundboards of classical guitars. By way of simulations, we evaluate their impact on the modal behaviour and on the sound pressure level of the instrument, as well as on its ability to sustain the load exerted by the strings. Our results show that the metamaterials can tune the instrument’s response without compromising its structural integrity. We thus conclude that the use of wooden mechanical metamaterials in the soundboards of classical guitars is feasible and, in many ways, beneficial, not the least since it opens the door to using non-traditional woods with bespoke density and stiffness.

Structural Responses of a Conceptual Microsatellite Structure Incorporating Perforation Patterns to Dynamic Launch Loads

Satellite systems undergo several operational phases during their service life, including the assembly phase, ground transportation phase, the launch phase, and the in-orbit operation phase. Among these phases, the one that imposes the highest level of loadings on the satellite is the launch phase. This phase involves a number of highly dynamic loads, all being imposed upon the satellite simultaneously. Investigation of the responses of the structural subsystem of a satellite to these loadings, namely its maximum deformations and maximum von Mises stresses, is critical if a reasonably high level of confidence is to be achieved. This confidence is in terms of ensuring that no material yielding develops in the structure as a result of the imposed launch loadings. In an earlier work, the structural subsystem of a conceptual microsatellite was designed, employing aluminum 6061 alloy as its material. It was then modified through introducing sets of parametrically defined geometric patterns as perforation patterns to remove material, towards reducing the structure’s total mass, as an alternative to employing composite materials. That effort led to a mass reduction percentage of 23.15%. The current work’s research effort focused on computing the responses of the perforated structure to three of the dynamic launch loads that are imposed upon satellites while being launched, namely quasi-static, random, and shock loads. These responses were then compared to those of the baseline, unperforated, version of the same structure. The values of these loads were taken from the relevant sources, with the values being nominal, and represented the loads that any satellite must qualify for before it can be accepted by the provider for inclusion in a launcher. After imposing these load values upon the structural design it was found that the structural responses indicated that the structure would successfully survive these loads without developing stresses that would lead to material yielding failure. This was deduced from computing the yield margins of safety for each loading case, and all margin values were positive, indicating that the structure, at its current development stage, did have sufficient capacity to withstand these loads without material yielding. This reinforced the conclusion of the earlier work, namely that the perforation concept did have sufficient merit to be further developed towards being implemented in future satellite designs.

Glove perforation in selected surgical procedures in a general hospital in La Habana, Cuba

SummaryBackgroundSurgical glove perforation constitutes a risk for the maintenance of aseptic technique and the risk of surgical site infection and occupational exposure to blood borne infections for healthcare workers.AimTo identify the frequency of glove perforation in selected surgical procedures.MethodsA cross-sectional descriptive observational study was carried out in the surgical unit of the Joaquin Albarrán Hospital (La Habana, Cuba) during the period September–December 2019. Gloves used by surgeons in major urgent or elective surgical procedures were collected and tested for perforations.Findings757 gloves from 149 surgeons and 8 surgical specialties were tested and 95 (25.8%) had perforations. The highest frequencies of glove perforations were reported in vascular surgery (50.0%), proctology (37.9%), urology (28.0%) and general surgery (26.1%). The selected surgical procedures with the highest frequencies were open radical nephrectomy (87.5%), splenectomy (57.1%), open adenomectomy (55.6%), limb amputation (46.2%) and hysterectomy (41.7%). Glove perforation occurred more frequently in consultant surgeons (28.8%) than in residents (20.9%) (P = 0.021), in surgeons with more years of surgical experience (P = 0.003) and longer procedure duration (P = <0.001). Most glove perforations were identified in the left hand (64.1%), while 23.1% were in the right hand and 12.8% in both hands. 51.2% occurred in thumb and index finger. Differences in the patterns of glove perforation were observed among the different surgical procedures.ConclusionsOur findings provide insights into the risk of glove perforation during selected surgical procedures and the need for prevention strategies to reduce adverse consequences of glove perforation in patients and healthcare workers.

Designing variable reflection coefficient for upstream and downstream terminations to study their effect on flame thermoacoustics

In this paper, the design, construction and results of experiments performed on a generic combustion system are presented. The setup is supplemented by various weakly frequency-dependent variable reflection coefficient (RC) devices as upstream and downstream acoustic terminations. The main objective of building such terminations is to provide a method to study burner/flame stability when it is placed between various acoustic configurations (RC: 0.1-0.9) and to determine the figure of merit of a burner based on the evaluation of its map of (in-)stability. Furthermore, burner design parameters such as the burner perforation pattern (holes diameter, pitch, perforation area, etc.) which will provide combustion stability for the widest range of burner's acoustic embedding conditions are identified. The experimental setup comprises of an upstream acoustic termination, a telescopic tube with adjustable length is placed after the upstream termination followed by the burner and the quartz tube. On the top of the quartz tube, the replaceable downstream terminations are installed. Nine downstream terminations are constructed by stacking plates of 0.25 mm thickness separated by spacers ranging from 0.1 to 1 mm thickness. Particularly, for the burners tested in this setup, the smallest hole diameter burner (with the largest perforation area) results in the largest stable region on the stability map in the parameter space. An increase in the flow velocity leads to an increase in the frequency of instability and makes a stable system tend to become unstable, while an increase in the equivalence ratio contributes to stabilizing system instability

Stereotomic and Tectonic Architecture from Structural Point of View: Case of a Single 10-Story Perforated Shell Structure

This paper is part of a research on innovative structural systems techniques in tall buildings and starts from the collaboration between the Department of Scientific Research and the Department of Architecture and Engineering at Polis University. The objective of this paper is to emphasize the structural differences between tectonic and stereotomic architecture by analyzing the different structural behaviors of both languages. The initial hypothesis is that an interaction field can be found where these two languages can be combined to propose a design method for a preliminary design process. The methodology goes through the following steps: the first step, analysis and determination of tectonic and stereotomic modelling approach; the second step, analysis of a single 10 story perforated shell structure by changing the openings ratio from a structural point of view and the third step, interpretation of results stating these two different architectural and structural profiles are intertwined. The instruments used are presented by a multivariate visualization method, an easy-to-use and as a key concept for generating the perforated pattern of the shell structure. They describe a visual and interactive, performance informed tool-using software of Rhino Grasshopper, Karamba 3D plugin, indicating the designer's preferences and concluding with the structural control of the model build. It is expected that the results will introduce a generative design method for architecture grounded on the stereotomic and tectonic modelling approach that can contribute towards the integration of structural rationality into preliminary architectural design process of tall buildings.

Incidence of Sinus Membrane Perforation Using Two Types of Implant Drills: An Ex Vivo Animal Study.

This ex vivo study evaluates the incidence of sinus membrane perforation during implant site osteotomy with two different types of drills and drilling techniques. Fifty goat heads with 50 sinus pairs (100 sinus sides) were assigned to two groups (osseodensification bur [OB] group and inverse conical shape bur [ICSB] group) to simulate transcrestal sinus elevation (50 sinus sides per group). An osteotomy was performed to pass through the lateral sinus wall no more than 3 mm. The integrity of the sinus membranes was examined and confirmed under a microscope. Of the 50 sinuses per group, the OB group presented with 14 (28%) perforated sinuses, while the ICSB group presented with 2 (4%) perforated sinuses. Of the 14 perforations from the OB group, 6 (42.9%) showed a pinpoint perforation pattern, 4 (28.5%) of which were not visible until direct air pressure was applied. Overall, the ICSB drill group demonstrated a lower sinus perforation rate than the OB group.

ORGANIC FERTILIZER AND NATURAL ZEOLITE EFFECTS ON MORPHOMETRIC TRAITS OF BRASSICA NAPUS L. POLLEN GRAINS

Morphological characteristics of Brassica napus pollen (polar axis, equatorial diameter, shape index, pattern of perforation of exines, and perimeter of perforation zones) were investigated by using scanning electron microscopy JEOL JSM-6390. The B. napus seeds were grown under various agroecological conditions, i.e., mineral fertilizer (NPK 60:60:60 t ha-1) separately and together with zeolite, chicken droppings (10 t ha-1) separately and together with zeolite (5 t ha-1), and control (without fertilizers) from 2018 to 2020 at the Bunin Yelets State University, Yelets, Russia. It was found that pollen grains of B. napus had an oblong-ellipsoid shape. In the polar view, the pollen grains were circular with straight sides, though in the equatorial view, elliptical. For the polar axis of the pollen grains in fertilizer application treatments, the minimum values ranged from 24.59 to 27.76 µm, whereas the maximum readings were 40.13 to 42.12 µm compared with control (21.56 µm, 41.52 µm). The coefficient of variation for fertilizer applications ranged from 8.86% to 14.10% compared with control (14.85%) for the polar axis. For the equatorial axis of the pollen grains, the minimum values varied from 11.61 to 15.63 µm, whereas the range for the maximum values was 19.74 to 23.96 µm compared with the control (13.63 µm, 21.88 µm). For the equatorial axis among the fertilizer applications, the coefficient of variation varied from 8.47% to 12.01% compared with the control (18.35%). For the perimeter of the exine perforation of the pollen grains, the minimum values ranged from 1.68 to 1.95 µm, whereas the maximum values varied from 4.34 to 7.12 µm compared with the control (1.34 µm, 5.68 µm). The coefficient of variation varied from 24.48% to 33.19% compared with the control (34.78%) for the perimeter of exine perforation. The shape index of the pollen grains of the B. napus varied from 1.96 to 2.07 µm (correct unit of measure?) compared with the control (2.03 µm). Overall, with the use of organic fertilizers and zeolite, the morphometric parameters of pollen grains were significantly enhanced.

Diffraction effects of artistic perforation in architectural form modeling

The authors analyzed the objects of architecture and design, in the design of which the technique of art perforation is used. The types of composite structures of the perforation pattern are differentiated: geometrical, bionic, pattern-symbol. The principles of interaction of perforated plane with light flux in the modeling of architectural form are considered. The authors made an analogy between the diffraction grating and perforation as identical structures of the physical and optical laws of light beam operation and described the experiment of the interaction of luminous flux, a perforated plane with different types of composite structures of the pattern and simple geometric shapes. The conclusions are made about the extensive compositional and artistic possibilities of receiving an artistic perforation.

Anatomical characteristics of profunda artery perforator flap in the posteromedial femoral region and its application in the reconstruction of oral and maxillofacial defects

Objective: To investigate the anatomical basis for the preparation of the profunda artery perforator flap (PAPF) in the posteromedial femoral region and its application in the reconstruction of oral and maxillofacial defects. Methods: Six lower limbs of Chinese adult cadavers were micro-surgically dissected. CT angiography (CTA) data of bilateral lower limbs of 6 patients was also collected retrospectively. The number, external diameter, pedicle length, and distribution of perforators in the posteromedial femoral region were recorded from the specimens and CTA data. Meanwhile, 10 patients with oral squamous cell carcinoma in the Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University from August 2018 to June 2021 were treated with the PAPF. At each follow-up, contour and function of recipient and donor site, as well as swallowing and speech function were evaluated. Results: A total of 19 profunda artery perforator were identified in 6 lower limb specimens. The outer diameter at the beginning of the source artery was (2.34±0.25) mm and the total length of the pedicle was (11.12±1.06) cm. CTA data analysis of 12 legs identified 15 perforators of profunda artery in the posteromedial region. Eleven perforators were septocutaneous, including 2 perforators with a common trunk, while the remaining 4 perforators were musculocutaneous. As for different patterns of perforators (septocutaneous perforators, musculocutaneous perforators and perforators with a common trunk), the longitudinal distance to the pubic tubercle was (19.95±2.43), (21.84±2.54) and (19.48±0.55) cm respectively. The horizontal distance to the posterior edge of gracilis was (3.54±1.10), (3.72±0.30) and (3.85±1.48) cm, respectively. The initial diameters of perforators was (2.4±0.4), (2.6±0.6) and 1.9 mm respectively. Ten cases of the profunda artery perforator flaps survived successfully after operation. The flap sizes ranged from 8 cm×6 cm to 12 cm×7 cm. The patients were evaluated at 1, 3 and 6 months, and with 6 months interval ever since. During the follow-up, the shape of the recipient site was ideal, and the swallowing and language functions were not significantly affected. There was only linear scar in the donor area, and the function of the thigh was basically normal. Conclusions: PAPF possessed a good anatomic stability, suitable vascular pedicle length and diameter, minor influence to the donor area, sufficient amount tissue with good quality. It is an ideal choice for head and neck reconstruction.

Low-Rank Approximation of Frequency Response Analysis of Perforated Cylinders under Uncertainty

Frequency response analysis under uncertainty is computationally expensive. Low-rank approximation techniques can significantly reduce the solution times. Thin perforated cylinders, as with all shells, have specific features affecting the approximation error. There exists a rich thickness-dependent boundary layer structure, leading to local features becoming dominant as the thickness tends to zero. Related to boundary layers, there is also a connection between eigenmodes and the perforation patterns. The Krylov subspace approach for proportionally damped systems with uncertain Young’s modulus is compared with the full system, and via numerical experiments, it is shown that the relative accuracy of the low-rank approximation of perforated shells measured in energy depends on the dimensionless thickness. In the context of frequency response analysis, it then becomes possible that, at some critical thicknesses, the most energetic response within the observed frequency range is not identified correctly. The reference structure used in the experiments is a trommel screen with a non-regular perforation pattern with two different perforation zones. The low-rank approximation scheme is shown to be feasible in computational asymptotic analysis of trommel designs when the proportional damping model is used.

Suprafascial radiological characteristics of the superthin profunda artery perforator flap

Traditional subfascial harvest of the profunda artery perforator (PAP) flap results in a thick flap, which routinely requires secondary thinning. The aim of this study was to characterize the suprafascial perforator anatomy of PAPs on preoperative computed tomography angiography (CTA) and correlate radiological findings with our clinical experience in extremity reconstruction. Suprafascial PAP anatomy was reviewed in CTAs in 159 thighs. Findings on CTA were correlated with intraoperative findings in a cohort of patients who had a PAP flap for extremity reconstruction. Two main perforator patterns, a "T" (superficial bifurcation) and "Y" (deeper bifurcation) were identified. The ratio between the total skin thickness and the distance from the skin to the perforator bifurcation point and the total skin thickness was higher in the "T" perforator pattern. A dominant "T" perforator (n=97) was more common than "Y" (n=62). A dominant "T" perforator was more common in women and with higher body mass index (BMI). In the clinical study, we found a positive correlation between the skin thickness of the bifurcation point of a dominant "T" perforator and the thickness of the superficial fascia where a thin PAP flap is elevated. A dominant "T" perforator on preoperative CTA accurately predicts thickness of a PAP flap elevated at the level of the superficial fascia.

Experimental study of the temporary plugging pattern of perforations by multi-particle size composites

In the process of temporary plugging and diverting fracturing of horizontal wells, the seating of large-size temporary plugging balls on the perforation is unstable and the plugging efficiency of irregular perforations is low, so a smaller-size composite temporary plugging agent is needed to improve the temporary plugging efficiency. In this study, based on the actual situation of Changqing oilfield, three kinds of temporary plugging materials with small particle sizes were used to plug the perforation. A simulated perforation plugging device with different permeability was built by artificial cores, and the plugging law and pressure-bearing capacity of the composite temporary plugging materials inside the perforation were studied. The results show that the temporary plugging materials with particle sizes smaller than the diameter of the perforation can form a plug inside the perforation, and the plugging zone formed inside the perforation is discontinuous. The plugging zone has good pressure-bearing performance, and the indoor blocking pressure is more than 15 MPa. The orthogonal experiments showed that the importance of three kinds of temporary plugging agents in the composite temporary plugging materials were 3-4 mm particles, 0.15 mm powder, and 1-2 mm particles, and the optimal ratio is 3:3:2. This study provides a technical basis for the design of the temporary plugging and diverting fracturing.

Modal Analysis of Conceptual Microsatellite Design Employing Perforated Structural Components for Mass Reduction

Mass reduction is a primary design goal pursued in satellite structural design, since the launch cost is proportional to their total mass. The most common mass reduction method currently employed is to introduce honeycomb structures, with space qualified composite materials as facing materials, into the structural design, especially for satellites with larger masses. However, efficient implementation of these materials requires significant expertise in their design, analysis, and fabrication processes; moreover, the material procurement costs are high, therefore increasing the overall program costs. Thus, the current work proposes a low-cost alternative approach through the design and implementation of geometrically-shaped, parametrically-defined metal perforation patterns, fabricated by standard processes. These patterns included four geometric shapes (diamonds, hexagons, squares, and triangles) implemented onto several components of a structural design for a conceptual satellite, with a parametric design space defined by two scale factors and also two aspect ratio variations. The change in the structure’s fundamental natural frequency, as a result of implementing each pattern shape and parameter variation, was the selection criterion, due to its importance during the launcher selection process. The best pattern from among the four alternatives was then selected, after having validated the computational methodology through implementing experimental modal analysis on a scaled down physical model of a primary load-bearing component of the structural design. From the findings, a significant mass reduction percentage of 23.15%, utilizing the proposed perforation concept, was achieved in the final parametric design iteration relative to the baseline unperforated case while maintaining the same fundamental frequency. Dynamic loading analysis was also conducted, utilizing both the baseline unperforated and the finalized perforated designs, to check its capability to withstand realistic launch loads through applying quasi-static loads. The findings show that the final perforated design outperformed the baseline unperforated design with respect to the maximum displacements, maximum Von Mises stresses, and also the computed margin of safety. With these encouraging outcomes, the perforated design concept proved that it could provide an opportunity to develop low-cost satellite structural designs with reduced mass.

Applicable Formulas for Shear and Thermal Buckling of Perforated Rectangular Panels

The goal of this study is to create semiempirical formulations for predicting thermal and shear buckling loads of perforated rectangular isotropic panels for eight combinations of boundary conditions. The finite element method (FEM) was used to develop and evaluate empirical formulations. In this study, the influences of plate aspect ratios, boundary conditions, and perforation sizes on the buckling strength of perforated panels subjected to shear and thermal loads are investigated. The proposed formulas will enable consistent and reliable computation of the buckling loads for perforated rectangular panels without the need for complex calculations. The results of the empirical equations were found to be reasonably consistent with the outcomes of finite element analysis (FE) and findings from the literature. Various perforation patterns are investigated, ranging from a single circular hole up to 441 circular holes distributed across the plate. The results show that plates with a single central cutout have lower shear buckling loads than plates with multiple holes and an equal total cutout area.

An optimization approach to design deformation patterns in perforated mechanical metamaterials using distributions of Poisson’s ratio-based unit cells

Two-dimensional metamaterials with patterns of perforations producing auxetic effects can exhibit variable and tailorable deformation mechanisms by varying the distributions of cells with different geometry parameters. The local homogenized Poisson’s ratio can be used as a way to establish as a link between local unit cell parameters and global deformations. We propose here a Poisson’s ratio-based unit cell distribution optimization method to design deformation patterns in a perforated structure. A plate-like structure with centresymmetric perforations is here divided into different regions with dissimilar unit cell topologies that possess different homogenized Poisson’s ratio values. All the unit cells belonging to the same region have equal geometry. A differential evolution (DE) algorithm is used to optimize the permutation and combination of the homogenized local Poisson’s ratios of the unit cells regions. A two-dimensional perforated structure that satisfies the required deformation pattern can be obtained by using the proposed method. Simulations and experiments show that the proposed approach can provide controllable shape changes of 2D perforated mechanical metamaterials under uniaxial tensile loading.

Ventilation effectiveness of uniform and non-uniform perforated duct diffusers at office room

Half of the energy usages in buildings is due to HVAC systems, and the efficiency of the subsections plays an essential role in the evaluation of the total energy consumption. Previous works on ventilation systems using perforated duct diffusers (PDDs) were mainly concentrated on the calculation of the thermal comfort indices, while their energy consumption and ventilation effectiveness were omitted. In this paper, a mixed experimental-numerical method has been developed to evaluate the real efficiency of PDDs with different perforation patterns. So, an office room facility is used for the full-scale experiments and the validation of the numerical simulations. Incidentally, five RANS models have been benchmarked to highlight the most accurate numerical model for this specific application. As a result, a k-ε Realizable turbulence model with 4.3 million mesh elements has been preferred over the tested two-equation turbulence models to determine the diffuser parameters like age of air, terminal velocities, air-change effectiveness, and air exchange efficiency. Within this model, the required outdoor airflow for four types of PDDs has been calculated following the ASHRAE standard procedure. The discrepancy of the real efficiency and the calculated value for the nearest application in the standards shows that the performance of PDDs is underestimated, and they require lower airflow in reality. Later, it is shown that for the systems using PDDs, the required airflow and energy consumption decrease by up to 18.4%, and a more uniform air distribution is achieved using a non-uniform perforation pattern.

Air Permeability, Shock Absorption Ability, and Flexural Strength of 3D-Printed Perforated ABS Polymer Sheets with 3D-Knitted Fabric Cushioning for Sports Face Guard Applications.

Sports face guards (FGs) are devices that protect athletes from maxillofacial injury or ensure rapid return to play following orofacial damage. Conventional FGs are uncomfortable to wear owing to stuffiness caused by poor ventilation and often slip off due to increase in weight due to absorption of moisture from perspiration, lowering players’ performance. Herein, combinations of 3D-printed perforated acrylonitrile butadiene styrene (ABS) polymer sheets and 3D-knitted fabrics with honeycomb structures as cushioning materials were investigated to balance better wearing feel and mechanical properties. The flexural strength, weight, and shock absorption ability of, and air flow rate through, the ABS sheets with five different perforation patterns were evaluated and compared with those of conventional FG materials comprising a combination of polycaprolactone sheets for the medical splint and polychloroprene rubber for the cushioning material. The ABS sheets having 10% open area and 2.52 mm round holes, combined with knitted fabric cushioning, exhibited the requisite shock absorbing, higher air permeability, and lower weight properties than the conventional materials. Our results suggest that FGs fabricated using combinations of 3D-printed perforated ABS polymer sheets and 3D-knitted fabrics with honeycomb structures may impart enhanced wearing comfort for athletes.

Development and Validation of a Prognostic Nomogram for Postoperative Recurrence-Free Survival of Ameloblastoma.

PurposeAmeloblastoma is a benign odontogenic neoplasm with a high local recurrence rate if the operation is not thorough. However, a useful clinical tool for the quantitative assessment of the prognosis and risk of postoperative recurrence of ameloblastoma has not yet been constructed. This study aims to develop a prognostic nomogram model for ameloblastoma of the jaw to assist surgeons in surgical decision-making.Patients and MethodsPatients who underwent initial surgery for ameloblastoma in our department from October 2004 to March 2020 were enrolled and randomly divided into training and validation sets. Univariate and multivariate Cox proportional hazards regression analyses were performed to identify the independent prognostic factors, from which a nomogram for predicting 3-, 5- and 10-year recurrence-free survival (RFS) of ameloblastoma was constructed using the training set and internally validated using the validation set. The model performance was assessed by Harrell's concordance index (C-index) and calibration curves.ResultsA total of 302 eligible patients with ameloblastoma were enrolled, 54 of whom were confirmed to relapse during the follow-up period of 6 to 191 months. Four independent predictors, including cortical bone perforation, root(s) resorption, WHO classification, and treatment pattern, were identified and included in the construction of a nomogram for recurrence-free survival (RFS), which showed promising calibration performance and discrimination in the training set (C-index 0.790, 95% confidence interval [CI] 0.735–0.845) and the validation set (C-index 0.734, 95% CI 0.599–0.869).ConclusionA favorable nomogram was developed that accurately predicted the RFS of patients with ameloblastoma based on individual characteristics. Risk stratification using the nomogram could optimize tailored therapy and follow-up.