Number Of Perforations Research Articles

A New Water Hammer Decay Model: Analyzing the Interference of Multiple Fractures and Perforations on Decay Rate

Summary Hydraulic fracturing technology is an important technique for developing tight oil and gas resources. Multicluster fracture diagnosis is significant for hydraulic fracture design and optimization. Water hammer fracturing diagnostic technology is an emerging diagnostic technology. Fracture network complexity can be assessed by the water hammer decay rate. In this paper, a new characteristic line coupling model for the fracture-wellbore system is proposed. This model calculates the number of fractures and perforations based on the water hammer signal. First, our paper defines a method for calculating the water hammer decay rate. Second, a characteristic line simulation method for water hammer coupled with fractures and perforations is proposed. Third, the effects of different fracture-wellbore systems on the water hammer decay rate are analyzed. The method is validated by laboratory experiments and numerical analysis. Finally, through a field case, the results of the number of fracture openings explained by the optical fiber and our model are compared to provide support for the field water hammer fracturing diagnosis. Our paper provides a new model for water hammer decay rate calculation and evaluation of fracture number.

The role of Atg16 in autophagy, anthocyanin biosynthesis, and programmed cell death in leaves of the lace plant (Aponogeton madagascariensis).

Aponogeton madagascariensis, commonly known as the lace plant, produces leaves that form perforations by programmed cell death (PCD). Leaf development is divided into several stages beginning with "pre-perforation" furled leaves enriched with red pigmentation from anthocyanins. The leaf blade is characterized by a series of grids known as areoles bounded by veins. As leaves develop into the "window stage", anthocyanins recede from the center of the areole towards the vasculature creating a gradient of pigmentation and cell death. Cells in the middle of the areole that lack anthocyanins undergo PCD (PCD cells), while cells that retain anthocyanins (non-PCD cells) maintain homeostasis and persist in the mature leaf. Autophagy has reported roles in survival or PCD promotion across different plant cell types. However, the direct involvement of autophagy in PCD and anthocyanin levels during lace plant leaf development has not been determined. Previous RNA sequencing analysis revealed the upregulation of autophagy-related gene Atg16 transcripts in pre-perforation and window stage leaves, but how Atg16 affects PCD in lace plant leaf development is unknown. In this study, we investigated the levels of Atg16 in lace plant PCD by treating whole plants with either an autophagy promoter rapamycin or inhibitors concanamycin A (ConA) or wortmannin. Following treatments, window and mature stage leaves were harvested and analyzed using microscopy, spectrophotometry, and western blotting. Western blotting showed significantly higher Atg16 levels in rapamycin-treated window leaves, coupled with lower anthocyanin levels. Wortmannin-treated leaves had significantly lower Atg16 protein and higher anthocyanin levels compared to the control. Mature leaves from rapamycin-treated plants generated significantly fewer perforations compared to control, while wortmannin had the opposite effect. However, ConA treatment did not significantly change Atg16 levels, nor the number of perforations compared to the control, but anthocyanin levels did increase significantly in window leaves. We propose autophagy plays a dual role in promoting cell survival in NPCD cells by maintaining optimal anthocyanin levels and mediating a timely cell death in PCD cells in developing lace plant leaves. How autophagy specifically affects anthocyanin levels remained unexplained.

Association of peptic ulcer perforation with ramadan related lifestyle modifications.

Objective: To look into the relationship of Ramadan with peptic ulcer perforation. This will include assessing the effect of fasting as well as other Ramadan related factors like changes in eating and smoking habits. Study Design: Retrospective Analysis. Setting: Three Tertiary care hospitals of Peshawar i-e Hayatabad Medical Complex, Khyber Teaching Hospital and Lady Reading Hospital. Period: 6th May 2019 to 26th May 2020. Material & Methods: Patients presenting with the aforementioned complication of peptic ulcer during the research period were divided into two groups. Patients presenting during the two Ramadan months were designated as cases (Group 1). While those presenting during the rest of the period i-e 11 months, were the controls (Group 2). So comparison of these groups was done on basis of various predisposing factors of the disease. Inferences were drawn by applying Student’s t, Chi-square and Fischer’s exact chi-square tests. Results: A total of 129 patients were considered. Among these, 36 were cases (Group 1) and 93 were controls (Group 2) as per our study design. Number of perforations per month were statistically higher in Group 1 in comparison to Group 2 (i-e 18 patients per month vs 8.4 patients per month, p<0.05). Patients with dyspepsia and preference for fried food were significantly higher in Group 1 (p<0.001 and p=0.022 respectively). Whereas smoker were significantly lower in Group 1 (p=0.048). Conclusion: Analysis concluded that the incidence of perforation is higher during the Ramadan. Since Ramadan is not only about fasting, and it affects eating and smoking habits, this rise in rate of perforations can be considered to be an interplay of such changes and the complication of peptic ulcer.

English

In Rwanda, the traditional fired solid bricks embody high fuel consumption and quantity of clay during their molding. Traditional solid bricks are also heavy compared to perforated bricks. This study aimed at investigating the performance of perforated clay bricks made of clay soil (CS) mixed with charcoal waste (CW) as an additive. The physical, chemical and mechanical properties of CS mixed with 0, 10, 30, 40 and 50% of CW were determined. The bricks were extruded manually with the inclusion of a varied number of perforations: 4, 8, 12 and 15 number perforations. The chemical analysis included the determination of organic carbon, exchangeable acidity and chemical components (through XRD) in the soil matrix. The chemical analysis depicted an increase in CaO proportions with an increase in charcoal waste content. There was also an increase in the amounts of exchangeable cations. The research found that with an increase in perforations, weight loss is reduced. However, non-perforated bricks depicted the least abrasion resistance, followed by bricks with 4 perforations. As the CW content increased from 0 to 50%, bricks with 15 and 12 perforations displayed the highest abrasion resistance. The research concludes that an increase in charcoal waste led to an increase in the linear shrinkage of clay soil bricks due to increased calcium cations and reduced magnesium cations in the soil. An optimum of 30% of charcoal waste was identified for the linear shrinkage of clay soil bricks. Bricks having 12 perforations and below with 30% charcoal waste additive can be categorized as category I (load-bearing) bricks.

New Perspectives about Maxillary Sinus Lifting: a Literature Review

Maxillary sinus lifting is a procedure for bone height gain in atrophic jaws. New safe and less complex manners have been evalueted, which use modifications of conventional techniques, through technologies such as devices and equipment that make them less traumatic. This study aims to conduct a literature review of articles found in the PubMed database between the years 2015 and 2020 that addresses advances in Maxillary sinus lifting techniques. We noticed that there is a development in the techniques that promotes the reduction of operative time, perforations and consequently a better postoperative for the patient, reducing the unpleasant perception of the surgery. The use of surgical ultrasound reduces the trauma to the soft tissues and the number of membrane perforations. A great step in the development of the sinus membrane lifting technique was the perception that bone formation is possible with the detachment of the membrane, not requiring the placement of a graft. There is no technique that replaces Maxillary Sinus Lifting yet. Only to improve it.

Investigating the simultaneous fracture propagation from multiple perforation clusters in horizontal wells using 3D block discrete element method

Multi-cluster horizontal well fracturing is one of the key technologies to develop the unconventional reservoirs such as shales. However, the field data shows that some perforation clusters have little production contribution. In this study, a three-dimensional (3D) numerical model for simulating the multiple fracture propagation based on 3D block discrete element method was established, and this model considers the stress interference, perforation friction and fluid-mechanical coupling effect. In order to determine the most appropriate measures to improve the uniformity of multiple fracture propagation, the effect of the geologic and engineering parameters on the multiple fracture propagation in shale reservoirs is investigated. The modeling results show that the geometry of each fracture within a stage is different, and the outer fractures generally receive more fracturing fluid than the interior fractures. The vertical stress almost has no effect on the geometries of multiple fractures. However, higher horizontal stress difference, larger cluster spacing, smaller perforation number, higher injection rate, and smaller fracturing fluid viscosity are conducive to promote the uniform propagation of multiple fractures. The existence of bedding planes will increase the fluid filtration, resulting in a reduction in fracture length. The middle two fractures receive less fluid and the width of them is smaller. Through analyzing the numerical results, a large amount of fracturing fluid should be injected and the proppant with smaller size is suggested to be used to effectively prop the bedding planes. Cluster spacing and perforation number should be controlled in an appropriate range according to reservoir properties. Increasing the injection rate and reducing the viscosity of fracturing fluid are important means to improve the geometry of each fracture.

Comparison of Self-Tapping Screws Versus Erich’s Arch Bar Wiring for Occlusion Maintenance in the Surgical Management of Mandibular Fracture: A Randomized Control Trial

Background: Conventional methods like Erich’s arch bars and eyelet wires are currently most common methods for achieving temporary inter-maxillary fixation (IMF).
 Objectives: The purpose of the present study was to compare the efficacy of Self-tapping screws over Erich’s arch bar wiring for inter maxillary fixation in the treatment of mandibular fractures.
 Methodology: This was a randomized control trial study. Study duration was one year from October 2014 to September 2015. This study involved patients with mandibular fractures aged 22 to 65 years who visited Department of Oral & Maxillofacial Surgery at Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. After random sampling according to inclusion and exclusion criteria surgical treatment was done by miniplate osteosynthesis. Study population were divided into two groups. In group A, temporary MMF was done with Erich’s arch bar and in group B treatment was given with self-tapping screws. The study outcomes were total time required for achieving temporary MMF, number of wire stick injury, stability of occlusion and oral hygiene index. All the parameters were measured preoperatively and postoperatively for 14 days up to removal of screws or arch bars.
 Results: The mean time taken for temporary MMF was 11.31±2.46 min with screws as compared to 84.72±14.30 min with Erich’s arch bar. Mean number of perforations were significantly more in group A. Occlusion stability was 69.2% in group A and 84.6% in group B. The mean value of plaque index in group A was 2.85±0.25 and in group B was 1.15± 0.16.
 Conclusion: In conclusion, plaque deposition was more in group A.
 Journal of National Institute of Neurosciences Bangladesh, July 2022;8(2):175-180

Effect of Mini-implant assisted Micro-osteoperforation on the rate of orthodontic tooth movement-A randomized clinical trial.

To evaluate the effectiveness of micro-osteoperforation (MOP) over a 56-day period and to determine the influence of number of perforations on the rate of canine retraction. In addition, the amount of pain and discomfort caused by the MOP was evaluated. A single-center, split-mouth, triple-blind, randomized, controlled trial. 22 patients (18-30 years) who need fixed orthodontic treatment were recruited and randomly assigned to MOP1 and MOP2 groups. The recruited patients were divided into two groups with 1:1 allocation ratio. Randomization for the determination of experimental side and number of perforations was done using sealed envelopes. On each patient, the other side of mouth worked as control side with no MOPs. 4 months after first premolar extraction, patients in MOP1 received 3MOPs on the buccal surface of alveolar bone, whereas patients in MOP2 received three buccal and three palatal MOPs in the experimental side. The amount of canine retraction was measured every 28 days at two intervals on both sides of mouth. Pain perception was measured after 1 hr, 24 hr, 72 hr, 7 days, and 28 days of procedure. Result of the intra-examiner reliability using ICC is more than 0.97 (P < 0.001), indicating excellent repeatability and reliability of the measurements. The baseline characteristics between groups were similar (P > 0.05). A statistically significant difference in the rate of canine retraction on the MOP side was observed at the end of 56 days, amounting to two folds more than that of the control side. No significant difference was seen between MOP1 and MOP2 groups (P > 0.05). Mild-to-moderate pain was experienced only in first 72 hours of procedure. The study recommends that MOP procedure has substantial potential to be used as an adjunct to the routine mechanotherapy for accelerating tooth movement, as it may reduce treatment time by half in the first four weeks after the MOP procedure. Clinical trial registry of India (CTRI/2022/12/048181).

Numerical study of perforated steel plate shear walls in staggered pattern

Steel plate shear walls (SPSW) consist of steel plates that are directly connected to columns and beams. The steel plate used as the filler is a thin and slender. One option to reduce the steel plate capacity is to provide perforations in the web plate. In this study, the parameters analysed were the influence of the perforation area on the arrangement of the staggered hole patterns on the steel plate panel. This study uses a numerical method. The result of the research is an analysis that explains the relationship between the percentage of perforation area on the load capacity and the stiffness degradation of the steel plate shear walls. The steel plate model is given a circular perforation with a diameter of 50 mm. The specimens were analysed at different number of perforations with a plate thickness of 1 and 2 mm. The results showed that every enhancement number of perforations, the load capacity and elastic stiffness will decrease. Changing the plate thickness from 2 mm to 1 mm, the load capacity also decreases. The initial stress distribution occurs on the diagonal side of the shear wall plate and then spreads to all parts of the shear wall plate.

Typhoid Intestinal Perforation Prognostic Score in Poor-Resource Settings.

Mortality from peritonitis due to typhoid intestinal perforation (TIP) in sub-Saharan Africa is high. This study aimed to determine the predictive factors of mortality, propose a prognostic score, and determine the appropriate surgical treatment for TIP in low-resource settings. This was a retrospective data collection of peritonitis due to TIP admitted at Zinder National Hospital from 2014 to 2021. To build a typhoid intestinal perforation prognostic score (TIPPS), patients were randomised into two groups: a score-building group and a validation group. Univariate and multivariate analyses were performed to identify risk factors of mortality. The value of P <0.05 was assigned significant for all analyses. TIP accounted for 52.4% (n = 1132) of all cases of peritonitis (n = 2159). The median age was 12 years. Rural provenance represented 72.2% (n = 817). Deaths accounted for 10.5% (n = 119). The factors influencing mortality were respiratory rate ≥24/min (odds ratio [OR] = 2.6, P = 0.000), systolic blood pressure <90 mmHg (OR = 0.31, P = 0.002), serum creatinine >20 mg/L (OR = 2.6, P ≤ 0.009), haemoglobin (OR = 2.1, P = 0.000), comorbidity (OR = 3.5, P = 0.001), the American Society of Anesthesiologists score IV&V (OR = 3.3, P = 0.000), admission and management delay > 72 h (OR = 3.2, P = 0.001), and a number of perforations (OR = 2.4, P = 0.0001). These factors were used to build a "TIPPS" score, which ranged from 8 to 20. The risk of mortality was associated with increased TIPPS. The performance of this score was good in the two groups (area under receiver operating characteristic > 0.83). According to the severity and mortality risk of TIP, we classified TIPS into four grades: grade I (low risk: 8-10), grade II (moderate risk: 11-13), grade III (high risk: 14-16) and grade IV (very high risk: 17-20). The TIPPS is simple. It can describe the severity of the disease and can predict the risk of death. The study highlights the importance and impact of timely and adequate perioperative resuscitation in more complicated cases.

Fully coupled aero-hydrodynamic analysis of a biomimetic fractal semi-submersible floating offshore wind turbine under wind-wave excitation conditions

With wind energy utilization shifting to the deep sea, floating offshore wind turbines (FOWTs) have huge potential to improve the competitiveness of offshore wind energy generation. However, traditional FOWT systems are often in force imbalance due to the unique swaying characteristics caused by the unfixed foundation and high center of mass of the platform. Therefore, a novel bionic semi-submersible floating platform based on Victoria Amazonia (with random fractal structure) is proposed to increase the hydrodynamic stability of FOWT. A regular fractal structure with similar number of perforations and perforated area is also implemented to verify the effectiveness of the bionic FOWT. In this study, the unsteady computational fluid dynamic approach is adopted to simulate the aerodynamic and hydrodynamic response. More specifically, the dynamic fluid-body interaction module integrated in STAR-CCM+ is employed to establish a FOWT numerical model with rotating blades, tower, and mooring line system. Furthermore, the volume of fluid model in conjunction with the 6-DOF solver was used to efficiently solve the fluid-induced dynamic motion of FOWT in a multi-phase flow composed of air and water. Finally, the fully coupled calculation of the fractal structure FOWT was performed using the established reliable numerical model. The maximum average thrust and power of 736.43 kN and 5294.04 kW are obtained by random fractal FOWT in aerodynamic responses, while in hydrodynamic amplitude responses, the maximum decreases of 19.16% are obtained by both random fractal and regular fractal structures. As for amplitude responses in heave and surge, the random fractal FOWT of 12.91% and 5.05% decreases performs relatively better than the regular one (11.48% and 4.09% decreases). In addition, the visualization of unsteady flow fields and vortices in fractal structures is investigated in detail. Compared with the regular fractal structure, vortices within random fractal structure interact adequately with the pontoon walls, resulting in higher energy absorption effect and stability.

Simulation and regulation of fractures asynchronous initiation-propagation for deep shale gas horizontal well fracturing

The intensive cluster fracturing technology is widely applied in deep shale reservoirs. However, field data show that the fracture initiation time and propagation length of each cluster are different, which causes significant non-uniformity and affects the fracturing results. In this paper, a hydraulic fracture asynchronous initiation and propagation model for deep shale gas is established based on mechanics theory, which can consider the influence of in-situ stress variation and stress interference effect on the fracture asynchronous initiation and propagation behavior. According to the model design parameters, deep shale hydraulic fractures are regulated and optimized in combination with the non-uniform flow-limiting perforation technology to achieve uniform fracture propagation. The results show that, the non-uniformity of each fracture is obvious using conventional uniform perforation. However, with non-uniform perforation, each cluster perforation number is adjusted, the difference of initiation time and each fracture propagation velocity is significantly reduced, and the length of all fractures tend to be basically the same. And the field monitoring data are in good agreement with the calculation results, which verifies the reliability of the model. This study can reduce design blindness of non-uniform flow-limiting perforation technique, and has an important theoretical guidance for the optimal design of fracturing.

Evaluation of the mean crushing load of perforated circular tubes undergoing progressive collapse

Perforations have been successfully employed for reducing the initial collapse load of tubes undergoing axial collapse. Most of the available literature evaluates the reduction in the initial collapse load through either experiments or numerical simulations. Theoretical models for calculating the mean crushing load are available for tubes without any perforations. In this study, the theoretical model proposed by Abramowicz and Jones is adapted to calculate the mean crushing force of circular tubes, having multiple perforations, undergoing collapse in the concertina mode as a function of the number of perforations, their size, and radius to wall thickness ratio of the cylinder. The mean load predictions from the model compared well with results from finite element (FE) simulations with a maximum deviation of 10%. The FE results indicated that the peak load during initial collapse is correlated well with the mean crushing load. Therefore, the presented model can be used for obtaining an indirect initial estimate of the effect of number of perforations and their size in reducing the initial collapse load.

Evolution of Near-Well Damage Caused by Fluid Injection through Perforations in Wellbores in Low-Permeability Reservoirs: A Case Study in a Shale Oil Reservoir

Abstract During the development of shale oil resources, fluid injection is usually involved in the process of hydraulic fracturing. Fluid injection through perforations causes near-well damage, which is closely related to the subsequent initiation and propagation of hydraulic fractures. This study is focused on the characterization of the temporal and spatial evolving patterns for near-well damage induced by fluid injection through perforations in the early stage of hydraulic fracturing. A coupled hydromechanical model is introduced in a case study in a shale oil reservoir in northwestern China. The model considers porous media flow during fluid injection. It also considers elasticity in the rock skeleton before the damage. Once the damage is initiated, a damage factor is employed to quantify the magnitude of injection-induced damage. Results show that damage evolution is highly sensitive to perforation number and injection rate in each individual perforation. Damage propagation is more favorable in the direction of the initial maximum horizontal principal stress. The propagation of damage is drastic at the beginning of fluid injection, while the damage front travels relatively slow afterward. This study provides insights into the near-well damage evolution before main fractures are initiated and can be used as a reference for the optimization of perforation parameters in the hydraulic fracturing design in this shale oil field.

Numerical Investigations of Perforated CFRP Z-Cross-Section Profiles, under Axial Compression.

Thin-walled elements, thanks to their good properties, are increasingly used in structural applications, especially in the aircraft and building industries. These kinds of structures are often perforated for reducing weight and to ease servicing and maintenance operations, e.g., in aircraft wing ribs. These perforations cause a redistribution of stresses in the element which may change the ultimate strength of the structure and their elastic stiffness. The buckling behaviour of structural members with perforations is significantly influenced by the size, location, shape and number of perforations. Therefore, it is necessary to investigate the influence of these kinds of cut-out parameters on thin-walled structure buckling and postbuckling behaviour. This study investigated numerically the buckling and postbuckling behaviour of thin-walled perforated composite profiles with a Z-cross-section subjected to compression load. Numerical calculations were performed using the finite element method in the ABAQUS® program. The study investigated the effect of localisation and geometric parameters of cut-outs on the buckling load, postbuckling equilibrium path and failure load. Moreover, the perforated profiles were compared with a profile without cut-outs, which were experimentally tested in previous research. Results showed that the perforated profiles with a Z-cross-section do not lose their stability in the post-critical range. What is more, a well-chosen arrangement of the holes may prevent the mechanical properties from deteriorating.

Numerical analysis of heat transfer from perforated fins of an induction motor housing

The major goal of this research article is to demonstrate how perforation on the fin surface of an induction motor’s housing improves cooling performance. Heat transfer study was also conducted between traditional fins and the suggested perforated fins housing. An Induction Motor (IM) overheats as a result of continuous operation, raising its temperature, lowering its performance and shortening its lifespan. The innovative designs and development of fins are necessary for effective cooling and enhancing the thermal performance of IM. In the present work, the thermal analysis of induction motor is carried out by means of providing the perforations on existing fins and varying perforation size from 4 mm to 10 mm diameters and number of perforation from 20 to 11, on fins and observed the steady state heat transfer and temperature variation. In this regard, the half part of IM is modelled because of symmetry and steady state thermal analysis is carried out for un-finned, solid fins and perforated fins using ANSYS software. Results show that, more reduction in temperature on the surface of IM is observed in case of perforated fins having 11 perforations of 10 mm diameter, as compared to the other cases.

Numerical simulation on the multiple planar fracture propagation with perforation plugging in horizontal wells

Intra-stage multi-cluster temporary plugging and diverting fracturing (ITPF) is one of the fastest-growing techniques to obtain uniform reservoir stimulation in shale gas reservoirs. However, propagation geometries of multiple fractures during ITPF are not clear due that the existing numerical models cannot capture the effects of perforation plugging. In this paper, a new three-dimensional FEM based on CZM was developed to investigate multiple planar fracture propagation considering perforation plugging during ITPF. Meanwhile, the fluid pipe element and its subroutine were first developed to realize the flux partitioning before or after perforation plugging. The results showed that the perforation plugging changed the original distribution of the number of perforations in each fracture, thus changing the flux partitioning after perforation plugging, which could eliminate the effect of stress interference between multiple fractures and promote a uniform fluid distribution. The standard deviation of fluid distribution in the perforation plugging case was only 8.48% of that in the non-diversion case. Furthermore, critical plugging parameters have been investigated quantitatively. Specifically, injecting more diverters will create a higher fluid pressure rise in the wellbore, which will increase the risk of wellbore integrity. Comprehensively considering pressure rise and fluid distribution, the number of diverters should be 50% of the total number of perforations ( N pt ), whose standard deviation of fluid distribution of multiple fractures was lower than those in the cases of injecting 10% N pt , 30% N pt and 70% N pt . The diverters should be injected at an appropriate timing, i.e. 40% or 50% of the total fracturing time ( t ft ), whose standard deviation of the fluid distribution was only about 20% of standard deviations in the cases of injecting at 20% t ft or 70% t ft . A single injection with all diverters can maintain high bottom-hole pressure for a longer period and promote a more uniform fluid distribution. The standard deviation of the fluid distribution in the case of a single injection was 43.62%–55.41% of the other cases with multiple injection times. This study provides a meaningful perspective and some optimal plugging parameters on the field design during IPTF.

Evaluation of Surgical Glove Perforation and Sharps Injury in Oral and Maxillofacial Surgery.

The risk of exposure to infections during surgery is partly mitigated by gloving. However, perforation can reduce the effectiveness of gloving as a barrier to exposure. This study aimed at investigating the frequency of surgical glove perforation and factors predictive of these in our oral and maxillofacial surgical practice. The study was carried out at the National Hospital and the University of Abuja Teaching Hospital, Abuja, Nigeria. Consenting patients requiring oral surgical interventions were consecutively recruited into the study. Similarly, surgeons and their assistants who consented to the study were also enlisted in the study. At the end of every surgical procedure, gloves used by the surgeons and the assistants were tested for perforation. Variables investigated included the rate of perforations, the influence of the type of gloving, single versus double gloving, type of anaesthesia, and duration of surgery on rates. At a minimum of three operators per procedure, a total of 154 participants were involved in the study and 895 gloves were used. The number of glove perforations was 117(13.1%) with 82 (70.1%) involving the surgeons. There were 58/117 (49.6%) cases of perforation involving the dominant hand. Forefinger glove perforation accounted for 62 (52.9%) cases. Wire-related perforations were 72 (61.5%). Overall, nine cases of percutaneous injury were recorded. Duration of operation and double gloving were the predictive factors for perforations. Risk of sharps injury was relatively high due to the high incidence of glove perforation.

Hydrothermal Performance Maximisation and Entropy Generation Minimisation of Different Perforated Pinned Heat Sink Designs for Electronic Cooling

Abstract To quantify the benefits of reducing entropy production and improving hydrothermal performance with varied thermal air characteristics through different perforated heat sinks, a numerical study was conducted. Various numbers of circular perforations are studied from 0 perforations to 5 perforations. In addition, perforation configuration is considered, such as circular (3CP), square (3SP), elliptic (3EP), and triangular (3TP) perforated pinned heat sinks, as well as three slotted pinned heat sinks (SPHSs) (3S, 6S, and 10S) and four notched pinned heat sinks (NPHSs) (3S, 6S, and 10S) (2.5 N, 5 N, 7.5 N, and 10 N). The numerical results showed that the 5-circular perforations heat sink model (5CP) generates the minimum entropy generation and the maximum hydrothermal performance (HTP), around 17% and 1.2, respectively compared to the zero-perforation model, while the circular perforated pinned heat sink (3CP) model produces the maximum reduction in entropy generation, generally around 13% with moderated HTP of 1.1. Moreover, when comparing slotted and notched pinned heat sinks, the 10S slotted and 10 N notched pinned heat sinks achieve 1.45 of HTP.

Mechanisms of Basement Membrane Micro-Perforation during Cancer Cell Invasion into a 3D Collagen Gel

Cancer invasion through basement membranes represents the initial step of tumor dissemination and metastasis. However, little is known about how human cancer cells breach basement membranes. Here, we used a three-dimensional in vitro invasion model consisting of cancer spheroids encapsulated by a basement membrane and embedded in 3D collagen gels to visualize the early events of cancer invasion by confocal microscopy and live-cell imaging. Human breast cancer cells generated large numbers of basement membrane perforations, or holes, of varying sizes that expanded over time during cell invasion. We used a wide variety of small molecule inhibitors to probe the mechanisms of basement membrane perforation and hole expansion. Protease inhibitor treatment (BB94), led to a 63% decrease in perforation size. After myosin II inhibition (blebbistatin), the basement membrane perforation area decreased by only 15%. These treatments produced correspondingly decreased cellular breaching events. Interestingly, inhibition of actin polymerization dramatically decreased basement membrane perforation by 80% and blocked invasion. Our findings suggest that human cancer cells can primarily use proteolysis and actin polymerization to perforate the BM and to expand perforations for basement membrane breaching with a relatively small contribution from myosin II contractility.