Perforation Diameter Research Articles

[Diagnostic value of identifying location and amount of free gas in the abdominal cavity by multidetector computed tomography in patients with acute gastrointestinal perforation].

Objective: To evaluate the relationships between the location and extent of diffusion of free intraperitoneal air by multi-slice spiral CT (MSCT) and between the location and size of acute gastrointestinal perforation. Methods: This was a descriptive case series. We examined abdominal CT images of 33 patients who were treated for intraoperatively confirmed gastrointestinal perforation (excluding appendiceal perforation) in the Department of General Surgery, Nanfang Hospital between January and September 2022. We identified five locations of intraperitoneal air: the subphrenic space, hepatic portal space, mid-abdominal wall, mesenteric space, and pelvic cavity. We allocated the 33 patients to an upper gastrointestinal perforation (n=23) and lower gastrointestinal perforation group (n=10) base on intraoperative findings and analyzed the relationships between the locations of free gas and of gastrointestinal perforation. Additionally, we established two models for analyzing the extent of diffusion of free gas in the abdominal cavity and constructed receiver operating characteristic (ROC) curves to analyze the relationships between the two models and the size of the gastrointestinal perforation. Results: In the upper gastrointestinal perforation group, free gas was located around the hepatic portal area in 91.3% (21/23) of patients: this is a significantly greater proportion than that found in the lower gastrointestinal perforation group (5/10) (P=0.016). In contrast, free gas was located in the mesenteric interspace in 8/10 patients in the lower gastrointestinal perforation group; this is a significantly greater proportion than was found in the upper gastrointestinal perforation group (8.7%, 2/23) (P<0.010). The sensitivity of diagnosis of upper gastrointestinal perforation base on the presence of hepatic portal free gas was 84.8% and the specificity 71.4%. Further, the sensitivity of diagnosis of lower gastrointestinal perforation base on the presence of mesenteric interspace free gas was 80.0% and the specificity 91.3%. The rates of presence of free gas in the subdiaphragmatic area, mid-abdominal wall, and pelvic cavity did not differ significantly between the two groups (all P>0.05). Receiver operating characteristic curves showed that when free gas was present in four or more of the studied locations in the abdominal cavity, the optimal cutoff for perforation diameter was 2 cm, the corresponding sensitivity 66.7%, and the specificity 100%, suggesting that abdominal free gas diffuses extensively when the diameter of the perforation is >2 cm. Another model revealed that when free gas is present in three or more of the studied locations, the optimal cutoff for perforation diameter is 1 cm, corresponding to a sensitivity of 91.7% and specificity of 76.2%; suggesting that free gas is relatively confined in the abdominal cavity when the diameter of the perforation is <1 cm. Conclusion: Identifying which of five locations in the abdominal cavity contains free intraperitoneal air by examining MSCT images can be used to assist in the diagnosis of the location and size of acute gastrointestinal perforations.

O150: Perforator Related Risk Factors for Perfusion Related Complications in DIEP Flap Breast Reconstruction

Abstract Introduction Despite advancements in DIEP flap breast reconstruction, perfusion related complications (PRCs) remain a concern. Such complications can negatively affect the aesthetic outcome, necessitate revisional surgery and delay adjuvant chemotherapy and radiotherapy. The aim of our study was to investigate the impact of perforator diameter, perforator row, and shortest distance between perforator and flap edge on the development of PRCs. Methods Prospectively kept data was retrospectively analysed for consecutive patients who underwent unilateral DIEP flap breast reconstruction from January 2008 to January 2023. Significant risk factors (p &amp;lt; 0.05) in univariate analysis were included in multivariate analysis to identify risk factors for PRCs. Additionally, receiver operating characteristic (ROC) curve analysis was conducted to identify the critical shortest distance between perforator and flap edge distinguishing PRCs. Results 292 cases of unilateral DIEP flap breast reconstruction were identified, with a mean patient age of 52.6 years. PRCs occurred in 65 (22.3%) cases. Multivariate logistic regression identified shortest distance between perforator and flap edge to have a significant impact on the incidence of PRCs. ROC curve analysis found the critical shortest distance between perforator and flap edge distinguishing PRCs to be 42.5mm. Conclusions Our study shows that the shortest distance between perforator and flap edge is the strongest predictor for PRCs in DIEP flap breast reconstruction. As several perforator related factors come into consideration when designing and performing DIEP flap breast reconstruction, our findings can guide surgeons in this decision making.

First standardized assessment of perforators and perforasomes of the occipital artery – An anatomical study

BackgroundFlaps have become an integral part of plastic and reconstructive surgery. The robust blood supply of such flaps is a prerequisite to reduce flap failure. Despite the reported versatility of the occipital flap, comprehensive anatomical studies on its perforators and perforasomes are lacking. Hence, we examined the perforators originating from the occipital artery and their associated perforasomes, aiming to fill this knowledge gap for reconstructive surgery techniques. Methods39 of 40 occipital arteries of 20 fresh anatomical head specimens were dissected. Perforators with a least an outer diameter of 0.50 mm were identified and injected with dye to color their respective perforasomes. Location and size of the colored skin areas were determined as well as the location of their perforators were documented and analyzed. ResultsIn total, 183 perforators were found and described. The mean diameter of these vessels was 0.88 ± 0.27 mm (0.5–2.1 mm). The mean area of the perforasomes was 1288.26 ± 662.51 mm2 (144.60–3890.60 mm2). They were localized over the whole nuchal and occipital area. Lastly, perforator diameters were significantly associated with the size of their resulting perforasomes. ConclusionThis study is the first comprehensive overview of perforators and associated perforasomes of the occipital artery on a respectable amount of specimen. The arterial supply of big portions of the occipital and nuchal area is provided solely by the perforators of the occipital artery. For flap surgery, perforator diameter is a crucial detail to be considered in the decision-making process.

Multi-objective optimization of heat charging performance of phase change materials in tree-shaped perforated fin heat exchangers

To enhance the convective heat transfer and overall thermal performance of horizontal latent heat storage (LHS) units, an innovative tree-shaped fin structure with perforations was introduced. A numerical simulation study examined the impact of perforation layers on the unit's overall performance. For a comprehensive analysis of the perforations' cumulative effect on the LHS unit, the Response Surface Methodology (RSM) was utilized to assess the influence of variations in perforation diameter and number on material consumption and heat exchange targets, deriving predictive correlations. The results indicated that compared to a non-perforated structure, the maximum improvement was observed with three layers of perforations, reducing material usage by 0.93%, while increasing the Nusselt number (Nu) and heat exchange by 10.19% and 36.51%, respectively. Moreover, the average temperature of the phase change material (PCM) in one and three perforated layers was higher than in the non-perforated tree-shaped fins, with complete melting times reduced by 5.37% and 2.51%, respectively. RSM results showed a negative linear correlation between increased perforation diameter and number with reduced material consumption, with the number of perforations having a more significant impact on heat exchange than their diameter. The Pareto optimal points obtained using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) demonstrated lower material usage and higher heat exchange. Compared to the non-perforated tree-shaped fins, the Pareto-optimized solutions reduced material consumption by 2%–2.68% and increased heat exchange by 79.42%–94.45%. Analysis of the flow field, temperature field, and phase change process revealed that perforations significantly enhanced the mixing of PCM in different areas of the tree-like fins and secondary flow, with temperatures near the perforations increasing by 5–7K and flow velocity by 3–4 times, significantly promoting convective heat transfer.

[Robotic-Assisted DIEP Flap Harvest for Autologous Breast Reconstruction: Case Report, Technical Aspects and Identification of Suitable Patients].

Robotic-assisted harvest of the deep inferior epigastric perforator (DIEP) flap is an innovative modification of the traditional open preparation for autologous breast reconstruction. It is assumed that donor-site morbidity (herniae, bulging) is reduced by minimising the fascial incision length in robotic-assisted DIEP flap harvest. This is the first report of a robotic-assisted DIEP harvest in Germany, which was performed in April 2023 at the University Hospital of Freiburg in an interdisciplinary approach of the Departments of Plastic Surgery, Urology and Gynaecology. To determine the value of this novel technique, we assessed the demand by retrospectively performing an analysis of potential patients and conducted a cost analysis based on the breast reconstructions with DIEP flap harvest performed between April 2021 and May 2023 at the Department of Plastic Surgery at Freiburg University Hospital. To this end, we carried out a retrospective analysis of preoperative CT angiographies to determine the proportion of patients suitable for a robotic-assisted procedure in a post-hoc analysis. Furthermore, we describe the basic robotic-assisted techniques and discuss the TEP and TAPP laparoscopic approaches. In line with the previously published literature, a short intramuscular course (≤25 mm) and a perforator diameter of≥1.5 mm and≥2.7 mm (subgroup) were defined as a crucial condition for the robotic-assisted procedure. We analysed 65 DIEP flaps harvested in 51 patients, of which 26 DIEP flaps in 22 patients met both criteria, i. e.≤25 mm intramuscular course and≥1.5 mm diameter of the perforator, while 10 DIEP flaps in 10 patients additionally met the criteria of the subgroup (≥2.7 mm diameter). Based on the intramuscular course of the perforators in the CT angiographies of those 26 DIEP flaps, a potential reduction of the fascial incision of 96.8±25.21 mm (mean±standard deviation) compared with the conventional surgical approach was calculated. The additional material costs in our case were EUR 986.01. However, ischaemia time was 33,5 minutes longer than the median of the comparative cohort. The robotic-assisted procedure has already proven to be a feasible alternative in a suitable patient population. However, further studies are needed to confirm that robotic-assisted DIEP flap harvest actually reduces harvest site morbidity and thereby justifies the additional costs and complexity.

Preliminary Qualitative Analysis of Plant Samples by High-performance Thin-layer Chromatography for the Presence of Steroid Sapogenins of Some Representatives of the Dioscoreacae, Fabaceae, Ranunculaceae, Melanthiaceae, Scrophulariaceae

Introduction. Results of original research carried out by means of high performance thin layer chromatography (HPTLC) of various plant samples (air-dry raw material) of Dioscoreaceae, Ranunculaceae, Fabaceae, Melanthiaceae, Scrophulariaceae families are presented in this article.Aim. To carry out preliminary qualitative analysis by HPTLC method of steroidal sapogenins composition in hydrolyzed extracts, obtained from vegetative samples of above-ground and underground organs of some Dioscoreaceae, Ranunculaceae, Fabaceae, Melanthiaceae, Scrophulariaceae families.Materials and methods. Extraction from pre-dehydrated raw materials was carried out with 50 % aqueous isopropanol (c.p.) in an ultrasonic bath, followed by acidic hydrolysis of O-glycoside bonds, evaporation and redissolution of dry residue in 99 % methanol (c.p.); purification from suspended solids by filtering through filters with 20 µm perforation diameter. HPTLC was performed on apparatus complex CAMAG (Switzerland) using HPTLC Aluminium sheets Silica gel 60 F254 plates 20 × 20 cm, which were cut to the size 20 × 10 cm.Results and discussion. After scanning densitometry at 254 nm, we found that the separation of isopropanol extracts, followed by redissolution in strong methanol in this solvent system allows a fairly acceptable separation and identification of the compounds studied. Comparison of the tracks of plant extracts was performed with standard samples of steroid sapogenins, whose methanol solutions were applied to one stain-strobe of track 1, provided that they had different Rf indices and coloration after derivatization.Conclusion. Diosgenin was identified in plant extracts of rhizomes and roots of Dioscorea nipponica and Dioscorea caucasica and in seeds of Trigonella foenum-graecum preliminarily. Sarsasapogenin was verified in extracts of fruits of Sophora japonica, tigogenin in extracts of seeds of Trigonella foenum-graecum, herb of Pulsatilla patens and herb of Veronica officinalis. Yamogenin was detected in extracts of seeds of Trigonella foenum-graecum and herb of Veronica officinalis. This work is exploratory in nature, assessing the presence of certain saponins by their sapogenins in selected extracts. We will optimize the HPLC separation procedure and choose other detection methods to unambiguously assess the co-presence of the studied sapogenins with approximately the same staining shades after derivatization and matching retention indices: there are pairs of steroidal sapogenins that have the same retention, we decided to group them in mixtures so that there would be separation within the group and subsequent comparison with the original extracts would make it possible to identify those or other sapogenins in such extracts.

Evaluation of synthetic sponge to control wave-induced currents in coastal waters

Based on National Oceanic and Atmospheric Administration (NOAA) Coral Reef Conservation Program, climate change causes coral bleaching. In response to the high roughness of coral colonies and reduced current velocity, coral reefs in near-shore regions are susceptible to accumulation of pollutants or sediments. This threatens coral reef ecosystems and causes several challenges. Controlling the wave velocity, Turbulent Kinetic Energy (TKE), and vortical structures help enhance advection/diffusion of particles from coral reef zones.In the current study, a device inspired by a marine sponge (synthetic sponge), was designed. A suction/pumping function was devised through two concentric perforated cylinders to simulate this mechanism in the synthetic sponge. Several physical and numerical experiments (using OpenFOAM software considering RANS modeling) were carried out to investigate the effects of geometrical characteristics (i.e., cylinder and perforation diameters) of synthetic sponge on wave hydrodynamics. Accordingly, wave attenuation, mean horizontal and orbital velocities, turbulent kinetic energy, and vortex structures were evaluated. In summary, the results indicated that the pumping flow can act as an energy recovery downstream of the sponge, and the horizontal velocity and TKE growing in the water column due to generation of special vortices. Therefore, the current synthetic sponge can improve momentum transfer.

Multi-Fracture Propagation Considering Perforation Erosion with Respect to Multi-Stage Fracturing in Shale Reservoirs

Shale gas is considered a crucial global energy source. Hydraulic fracturing with multiple fractures in horizontal wells has been a crucial method for stimulating shale gas. During multi-stage fracturing, the fracture propagation is non-uniform, and fractures cannot be induced in some clusters due to the influence of stress shadow. To improve the multi-fracture propagation performance, technologies such as limited-entry fracturing are employed. However, perforation erosion limits the effect of the application of these technologies. In this paper, a two-dimensional numerical model that considers perforation erosion is established based on the finite element method. Then, the multi-fracture propagation, taking into account the impact of perforation erosion, is studied under different parameters. The results suggest that perforation erosion leads to a reduction in the perforation friction and exacerbates the uneven propagation of the fractures. The effects of erosion on multi-fracture propagation are heightened with a small perforation diameter and perforation number. However, reducing the perforation number and perforation diameter remains an effective method for promoting uniform fracture propagation. As the cluster spacing is increased, the effects of erosion on multi-fracture propagation are aggravated because of the weakened stress shadow effect. Furthermore, for a given volume of fracturing fluid, although a higher injection rate is associated with a shorter injection time, the effects of erosion on the multi-fracture propagation are more severe at a high injection rate.

Parametric study on the assessment of the local buckling behavior of perforated square hollow sections with non-uniform wall thickness under axial compression

The aim of this rigorous parametric study is to explore the influence of perforations on the local buckling behavior of square hollow sections (SHSs) possessing non-uniform wall thickness. A finite element procedure followed in the current study has been first validated against existing test results documented for the local buckling behavior of the perforated SHS with uniform web and flange segment thickness under axial compression. The linear elastic eigenvalue buckling and elastoplastic buckling analyses have been implemented using the Abaqus engineering finite element code. The verification of the numerical procedure has been achieved by favorably comparing the finite element results with the existing test results in terms of the first local buckling mode shape and load-end shortening curves of the perforated SHS with uniform wall thickness. . The verified numerical procedure has been applied to the problem of finding the perforation effect on the local buckling response of the SHS with non-uniform thickness. Finite element analyses have been performed for four various web width-to-perforation diameter ratios ranging from 0.3 to 0.9. Finite element analysis results have revealed that the presence of perforations does not influence the local buckling mode shape of the SHS but considerably affects the critical local buckling loads. The results have put forth that increasing perforation diameter leads to a more pronounced and drastic decrease in the critical local buckling load. The outcomes of the study have also shown that the critical post-buckling load of the SHS with non-uniform wall thickness is less susceptible to perforations compared to the SHS with uniform wall thickness. The results obtained in the context of this parametric study have been made available to practical engineering for use in actual design of the perforated SHSs.

Sound Absorption Characteristics of Integrated Membrane-Fabric Materials

Noise pollution has emerged as one of the most important environmental issues, particularly in developing countries. The use of sound absorption material has proven to be a successful approach for minimizing and controlling noise levels. Combining a membrane or panel with two or more porous materials is a practical approach for sound absorption. However, it often makes the absorber thicker, taking up more space and increasing production costs. This research proposes a new integrated sound absorber that combines a rubber membrane with a fabric to absorb sound at different frequencies. The new material eliminates bulky porous materials, saving space and production costs. By varying perforation sizes, percentages, and backed air gap distances, the study investigates the sound absorption characteristics of the integrated membrane-fabric material. The research has determined that the integrated membrane-fabric material exhibits exceptional sound absorption performance across a wide frequency range, which is influenced by several factors, including the diameter and ratio of perforations, and the depth of the air cavity. Furthermore, the investigation revealed that the positioning of the fabric also plays a crucial role in determining the material's absorption performance.

Acoustic properties of natural fiber reinforced composite micro-perforated panel (NFRC-MPP) made from cork fiber and polylactic acid (PLA) using 3D printing

The present study investigated the acoustic performance of biodegradable MPP absorbers made of natural fiber-reinforced composites (NFRC) using 3D printing. The novelty of this current research lies in the recent development of a methodology that aids industry professionals in optimizing the production of MPP (Micro-Perforated Panel) at a competitive cost. This is achieved by addressing and eliminating various issues commonly faced in traditional manufacturing processes, such as manual preparation and pressing. The FDM technique was used to fabricate test samples utilizing the PLA/corkwood composite. Using an impedance tube device with two microphones, the acoustic absorption coefficients of MPPs with different perforation diameters, thicknesses, and perforation rates were measured. Maa's analytical model was used to predict the acoustic absorption performance. Moreover, considering the average sound absorption and total cost of fabricating the samples, RSM-CCD was employed to optimize these samples. In the end, the parallel arrangement of MPP double layer and the combination of MPP with kenaf porous material were tested in order to improve the sound absorption performance. The results showed that the average sound absorption coefficient of the NFRC-MPP sound absorber is 25 % more than that of conventional MPP sound absorbers. The sample with a perforation diameter of 0.70 mm, a panel thickness of 0.90 mm, and an 8 mm distance between the perforations was selected as the optimal sound absorber. The measurement and model data for NFRC-MPP panels do not correspond well. The parallel arrangement of two layers of MPP and the addition of an optimized kenaf layer behind the MPP significantly improved the sound absorption performance in the intended frequency range. The findings of this study, coupled with data available in the literature for other types of biocomposite Micro-Perforated Panel (MPP), strongly indicate that Cork fiber-based MPP exhibits substantial promise for application, either independently or in conjunction with Kenaf materials, as a material for acoustic conditioning. Implementing smart manufacturing techniques for acoustic panels not only enhances engineering noise control efforts but also amplifies the overall effectiveness of Hearing Conservation Programs.

Associated Factors of Leaked Repair Following Omentopexy for Perforated Peptic Ulcer Disease; a Cross-sectional Study.

Previous studies have reported numerous clinico-pathologic risk factors associated with increased risk of leaked repair following omental patch for perforated peptic ulcer disease (PPUD). This study aimed to analyze the risk factors associated with leaked repair of omental patch and document the management and outcome of established cases of leaked repair in a resource-poor setting. This is a multicenter cross-sectional study of leaked repair after omental patch of PPUD between January 2016 to December 2022. Following primary repair of PPUD with omental pedicle reinforcement, associated factors of leaked repair were evaluated using univariate and multivariate analyses. Overall, 360 cases were evaluated (62.8% male). Leaked repair rate was 11.7% (42 cases). Those without immunosuppression were 3 times less likely to have leaked repair (aOR= 0.34; 95% CI: 0.16 - 0.72; p = 0.003) while those with sepsis were 4 times more likely to have leaked repair (aOR=4.16; 95% CI: 1.06 - 12.36; p = 0.018). Patients with delayed presentation (>48 hours) were 2.5 times more likely to have leaked repair than those who presented in 0 - 24 hours (aOR=2.51; 95% CI: 3.62 - 10.57; p = 0.044). Those with Perforation diameter 2.1-3.0 cm were 8 times (aOR=7.98; 95% CI: 2.63-24.21; p<0.0001), and those with perforation diameter > 3.0cm were 33 times (aOR=33.04; 95% CI: 10.98-100.25; p<0.0001) more likely to have leaked repair than those with perforation diameter of 0-1.0 cm. Similarly, in those with no perioperative shock, leaked repair was 4 times less likely to develop than those with perioperative shock (aOR= 0.42; 95% CI: 0.41-0.92; p = 0.041). There was significant statistical difference in morbidity (p = 0.003) and mortality (p < 0.0001) rates for cases of leaked repairs and successful repairs. Leaked repair following omentopexy for peptic ulcer perforation was significantly associated with large perforation diameter, delayed presentation, sepsis, immunosuppressive therapy, and perioperative shock.

Intra-Aortic Balloon Pump Support in Patients with Acute Myocardial Infarction with Ventricular Septal Rupture

Background: An intra-aortic balloon pump (IABP) is the device most frequently used as a bridge to surgical repair in cases of myocardial infarction. However, robust evidence of IABP support for patients with postinfarction ventricular septal rupture (VSR) remains lacking. This study was aimed at assessing the effect of IABP support on 30-day prognosis in patients with acute myocardial infarction (AMI) complicated by VSR. Methods: Retrospective data for patients with VSR after AMI at Fuwai Hospital between April 2002 and August 2020 were analyzed. Patients were initially stratified into two groups according to IABP implantation. The Kaplan-Meier method was used to determine the cumulative incidence of 30-day all-cause mortality. Multivariate logistic regression was used to evaluate the independent risk factors for 30-day mortality. Results: A total of 92 patients (mean age of 67.8 ± 8.3 years; 46.7% male) were included, 59 of whom underwent IABP implantation. Patients with rather than without IABP treatment were younger, were more often male, and had a higher body mass index and lower mean blood pressure at the onset of VSR. At 30 days, all-cause death occurred in 21 patients in the IABP group (35.59%) and 31 patients in the group without IABP (93.94%). After adjustment for age, sex, left atrial diameter, left ventricular diameter, perforation diameter and ventricular aneurysm, IABP support was found to be an independent protective predictor of 30-day all-cause mortality (hazard ratio: 0.22; 95% confidence interval: 0.12 to 0.42; P &lt; 0.001). Conclusions: IABP support was associated with lower 30-day mortality in patients with VSR after AMI. Patients with postinfarction VSR with hemodynamic instability or cardiogenic shock could receive IABP treatment as a bridge to surgical repair.

[Anatomical study of the architecture of the cutaneous branch-chained blood vessels in the medial lower leg in adult].

Objective: To investigate the architecture of the cutaneous branch-chained blood vessels in the medial lower leg and provide the anatomical basis for design and clinical application of the cutaneous branch-chained flap from this region. Methods: The experimental research method was used. From March to May 2023, the anatomical study was conducted on the 5 voluntarily donated fresh adult (aged 50 to 70 years, all male) cadaveric specimens from Hangzhou Normal University School of Basic Medical Sciences. The fine anatomy under microscope was performed on each lower leg specimens of 5 corpses (1 lower leg specimen was conducted with digital radiography (DR) scan before fine anatomy), to observe, measure, and record the course of posterior tibial artery, quantity of perforator, the distance between the perforating point of each perforator and the medial condyle of tibia, the external diameter of posterior tibial artery perforator, the length of perforator pedicle, the horizontal distance between the posterior tibial artery perforator and the saphenous nerve, and the course of each perforator within superficial fascia after crossing the deep fascia and the distribution of the cutaneous branch-chains. The DR scan under the perfusion of barium sulfate was conducted in one lower leg specimen to observe the distribution of cutaneous branch-chained vascular network (hereinafter referred to as vascular chain) between perforators. Transparent skin specimen was made from one leg specimen after anatomy to observe the distribution of perforators and vascular chains between perforators. Results: In 5 lower leg specimens, the upper part of posterior tibial artery was located deep in soleus muscle, and the lower part was located between the medial edge of gastrocnemius muscle and flexor digitorum longus muscle. A total of 28 posterior tibial artery perforators were identified, with an average of 5.6 branches in each lower leg. The distance between the perforating point of perforator and the medial condyle of tibia ranged from 6.5 to 36.0 cm, mainly distributed at 22.0 (15.1, 28.1) cm from the medial condyle of tibia, in zones 3 to 6. The external diameters of perforators of posterior tibial arteries were 0.7-1.1 mm. The length of perforator pedicle was 1.0-4.5 cm, and the horizontal distance between the posterior tibial artery perforator and the saphenous nerve was 0.5-3.0 cm. The fine anatomy under microscope showed that the posterior tibial artery perforators had long upward and downward branches after crossing the deep fascia, and the ascending branches and descending branches were anastomosed longitudinally to form the nutrient cutaneous branch-chain in the medial lower leg. DR scan and transparent skin specimen both showed that longitudinal vascular chain was formed between the posterior tibial artery perforators, the transparent skin specimen also showed that longitudinal blood vessel chains included the direct connecting vessels in the adipose layer and the indirect connecting vessels in the subdermal layer. Conclusions: The cutaneous branch-chained vessels in the medial lower leg are constructed by posterior tibial artery perforators, direct connecting vessels, indirect connecting vessels, and traffic branches. The cutaneous branch-chained flap is reliable in terms of vascular anatomy, and can carry the saphenous nerve for partial restoration of its sensation, thus it is an ideal flap.

Investigation and Application of Perforation Optimization Method on Shale Gas Horizontal Well with Numerical Simulation of Multicluster Fracturing under Dense-Segment Pattern

Investigation and Application of Perforation Optimization Method on Shale Gas Horizontal Well with Numerical Simulation of Multicluster Fracturing under Dense-Segment Pattern

Perforation Characteristics of Three-Layer Steel Plates Subjected to Impact with Different Shapes and Velocities of Reactive Fragments

In this paper, the AUTODYN/Smoothed Particle Hydrodynamics (SPH) method was used to study the impact of reactive fragments on three-layer equidistant steel plates. The perforation characteristics of equidistant three-layer steel plates were investigated along with the parameters of combustion energy release from reactive fragments under varied impact velocities and shape conditions. The modification of the steel plates’ perforation diameter was investigated using the dimensional analysis approach. The shock wave pressure and chemical reaction characteristics were examined using the shock wave theory. The results show that within the examined impact velocity range, the perforation diameter initially increased and then decreased as the impact velocity of the reactive fragment rose. In addition, the perforation diameter was approximately 1.5–3 times the diameter of the reactive fragment. As the impact speed increased, the active reaction generated by the reactive fragments became more sufficient. The energy released contributed to the impact’s pressure rise; in addition, the temperature of the steel plate was raised in part by the reactive fragment impact, making the steel plate more prone to melting. The results of this investigation provide important support for a detailed understanding of the rules governing the failure of steel plates under the impact of reactive fragments as well as the combustion of reactive fragments under impact.

Thermal performance promotion of a novel double-tube heat exchanger by helical fin with perforations

Double-tube heat exchangers are widely used in many fields. A novel double-tube heat exchanger with a perforated helical fin on the annulus side is proposed in this paper for thermal performance promotion. The effect of different perforation diameters ranging from 0 to 12 mm on the fluid flow and heat transfer are numerically studied under a turbulent state with Re ranges between 4000 and 16,000. The results showed that perforation diameter has a significant influence on the thermal performance. There exists an optimum perforation diameter for the best thermal performance. The largest value of Nu in the helical finned annulus increases by 20.2% by perforation, while the corresponding f only increases by 11.0% compared with the normal helical finned configuration without perforation. The thermal performance evaluation factor JF is also improved by up to 16.1% compared with the helical finned configuration without perforation, and is increased by 48.6% compared with the smooth annulus. Correlation formulas of f, Nu, and JF are fitted and the deviations are within ±4%, ±9%, and ± 5% for f, Nu, and JF, respectively. Perforated helical fin is an efficient annular-side heat transfer enhancement technology that can be applied to the optimized design of double-tube heat exchangers.

Sound Absorption Performance of Coir Fiber/Polylactic Acid Composite Microperforated Panel

Microperforated panel (MPP) is considered a unique and promising sound absorber, as its sound absorption performance depends on parameters such as perforation ratio, perforation diameter, and air gap thickness. In this study, the MPP was fabricated through conventional mixing, granulating, and hot compression methods. The MPP was made from coir fiber/polylactic acid (PLA) composite, outside the norm of using metallic materials to produce MPP. The panel's sound absorption performance was measured using an impedance measurement tube and then compared with pure PLA MPP, which was taken as a benchmark for this study for a fair comparison. The MPP produced in this study demonstrated outstanding sound absorption performance due to its porous and tortuous structure. The porous and tortuous structure coincided with the perforated hole mechanism in absorbing sound; thus, the performance was better than pure PLA MPP, which did not possess an apparent porous and tortuous structure. This study proved that natural fiber composite has considerable potential to be used for MPP production, as it is a sustainable and natural resource that brings less harm to the environment compared to the common usage of metallic materials.

Vibration of microperforated plate with spatial distribution of multiple-sized perforations

Recent works by the authors on homogeneous MPPs have highlighted the structural damping capabilities of MPPs in the low frequency range. The developed theoretical approach was based on the analogy between an MPP and a porous plate. The added damping is due to visco-thermic effects coupled to fluid-structure interactions. The added damping maxes out at a characteristic frequency depending on perforation diameter. In order to reduce plate vibrations, it was advised to match the characteristic frequency to a plate mode. It is proposed here to maximize the added damping effect on several vibration modes by focusing on MPPs with multiple-sized perforations and with spatial distribution of perforations. As an extension of the previous analytical model, an approach based on the electro-acoustic analogy is established to capture the effect of multiple-sized perforations. Moreover, a perforation ratio gradient is included in the approach to model an MPP with inhomogeneous spatial distribution of perforations. Experimental measurements on MPPs validate the proposed analytical model. Results show that: (i) MPP with multiple-sized perforations increases the frequency band of the effective damping; (ii) the added damping increases when the perforations are distributed around the antinodes of the considered mode, (iii) the two effects can be combined.

Optimization of micro-perforated panel absorber backed with parallel-arranged cavities of different depths

Micro-perforated panel absorber (MPA) is one of the most effective materials in noise control. For the MPA backed with parallel-arranged cavities of different depths (PCD-MPA), the panel thickness, perforation diameter, perforation rate, and cavity depth are essential parameters for absorption performance. In this study, a Genetic Algorithm (GA)-based optimization design method for PCD-MPA is proposed to achieve specific performance objectives. Firstly, a prediction model for absorption performance of PCD-MPA is proposed. Secondly, a GA optimization method suitable for PCD-MPA is established, taking into account interactive parameters and generating multi-objective and high-quality optimal solutions through iterative adjustments. Finally, an acoustic standard sample was fabricated for experimental validation and compared with analytical results. The findings demonstrate that the proposed optimization method can achieve nearly perfect absorption with a well-selected combination of parameters that meet specific absorption requirements.