An Enhanced Temperature Control Approach to Simulate Profile Extrusion.

Thermoplastic extrusion, a widely used method for processing thermoplastic materials, requires precise temperature control to ensure product quality. However, existing computer-aided engineering tools often oversimplify the temperature distribution calculations, leading to additional discrepancies between simulations and the actual processes. This study introduces a novel multi-region modeling approach to address this issue. By employing realistic temperature control conditions, the methodology overcomes the limitations of current numerical modeling tools. The key contributions include the development of a transient, incompressible, non-isothermal solver integrated into the OpenFOAM computational library and the implementation of a specialized boundary condition that emulates Proportional-Integral-Derivative (PID) control using real-time thermocouple measurements. The findings highlight temperature deviations at the flow channel walls and total pressure drop while demonstrating a smaller impact on velocity and flow uniformity at the outlet under steady-state conditions. This research substantially advances the understanding of thermal dynamics in extrusion processes, offering crucial insights for enhancing temperature control and laying the groundwork for more effective and precise operational strategies.

Computational Framework to Model the Selective Laser Sintering Process.

Selective laser sintering (SLS) is one of the most well-regarded additive manufacturing (AM) sub-processes, whose popularity has been increasing among numerous critical and demanding industries due to its capabilities, mainly manufacturing parts with highly complex geometries and desirable mechanical properties, with potential to replace other, more expensive, conventional processes. However, due to its various underlying multi-physics phenomena, the intrinsic complexity of the SLS process often hampers its industrial implementation. Such limitation has motivated academic interest in obtaining better insights into the process to optimize it and attain the required standards. In that regard, the usual experimental optimization methods are time-consuming and expensive and can fail to provide the optimal configurations, leading researchers to resort to computational modeling to better understand the process. The main objective of the present work is to develop a computational model capable of simulating the SLS process for polymeric applications, within an open-source framework, at a particle-length scale to assess the main process parameters' impact. Following previous developments, virgin and used polymer granules with different viscosities are implemented to better represent the actual process feedstock. The results obtained agree with the available experimental data, leading to a powerful tool to study, in greater detail, the SLS process and its physical parameters and material properties, contributing to its optimization.

Trapeziectomy and Suture-Button Suspensionplasty for Basilar Thumb Arthritis: Is It Enough to Prevent First Ray Subsidence?

Introduction Trapeziectomy and suture-button suspensionplasty (SBS) are a novel option to treat end-stage trapeziometacarpal (TMC) osteoarthritis. Our purpose is to evaluate our outcomes with this technique and in this setting, with a minimum of 18 months of follow-up. Materials and Methods Twenty-eight patients were included, operated between 2016 and 2018. We recorded demographic data, preoperative Eaton stage, follow-up and operative times. The patients completed the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) questionnaire and tip pinch, key pinch, and grip strength were measured. First metacarpal subsidence was calculated, and postoperative complications were documented. Results The average follow-up was 34 months. The mean QuickDASH was 32 at the final follow-up. The average strength results were 20 kg for grip, 3.6 kg for tip pinch, and 4.2 kg for key pinch. The rate of first ray subsidence was 10.7%. We encountered three complications: a hardware intolerance, a second metacarpal fracture, and a suture rupture. There was one reoperation to remove an implant. Conclusion Trapeziectomy and SBS functional results are similar to other techniques, with less subsidence of the first ray and allowing for early mobilization and fast recovery. This procedure is a safe and promising option in the treatment of TMC osteoarthritis, with good medium-term outcomes.

Bilateral hip heterotopic ossification with sciatic nerve compression on a paediatric patient-An individualized surgical approach: A case report.

BACKGROUND: Neurogenic heterotopic ossification is an acquired serious complication described in patients with central nervous system disorders and defined by bone formation in non-osseous tissue. CASE SUMMARY: We present an unusual case of a 13-yr-old boy presenting with hip pain and severe gait impairment 5 mo after the diagnosis of hemiplegia following a spontaneous intracerebral haemorrhage. Computed tomography revealed bilateral heterotopic ossification of both the paretic and the non-paretic limbs, with entrapment of the sciatic nerve. The choice of surgical or nonsurgical management of such patients depends on the timing of diagnosis, the symptoms, and the extent of maturation of the ossified lesions. Surgical resection remains the only treatment with proven, evidence-based effectiveness. The choice of surgical approach largely depends on the location of the ossified lesions. CONCLUSION: We believe the plane of dissection presented is a satisfactory option for resection of a posteromedial mass and sciatic nerve release.

Anterior Slope Correction-Flexion Osteotomy in Traumatic Genu Recurvatum.

A decreased posterior tibial slope has been associated with an increased risk of posterior cruciate ligament failure, anterior knee pain, and premature knee osteoarthritis. Trauma is a common cause of osseous genu recurvatum. Surgical management is recommended to correct the tibial slope and prevent knee pain and osteoarthritis progression. This article discusses our preferred treatment using a proximal tibial opening-wedge osteotomy for surgical management of genu recurvatum secondary to significant anterior tibial slope.

Is bilateral hallux valgus chevron osteotomy a safe procedure for ambulatory surgery?

INTRODUCTION: Several osteotomies of the first metatarsal have been described for treatment of hallux valgus but chevron osteotomy is one of the most common and well-established procedure for treating this deformity. Although there is a trend towards considering bilateral surgery there is lack of publications addressing bilateral treatment in ambulatory units. The aim of this study is to analyze results of bilateral and unilateral distal chevron osteotomies associated with lateral soft tissue release as ambulatory procedures. MATERIALS AND METHODS: A retrospective review was made about the patients treated at our ambulatory unit over a period of five years. Initially, general information as patient's satisfaction's rate and return to normal activity's time and evaluation of standardized follow-up charts and records made by the surgeon were recorded. Secondly, the hallux metatarsophalangeal interphalangeal scale developed by the American Orthopedic Foot & Ankle Society was used. RESULTS: A total of 194 patients with 230 feet operated were included in this study. We found 29 patients that didn't meet the inclusion criteria and were excluded. The unilateral group was composed by 139 feet and the bilateral group by 52 feet. The improvement between preoperative and discharge clinical and radiographic results was significant independently in both groups. A total of 14% of complications were found in our study, 19% in the unilateral group and 12% at the bilateral group. None of them required revision surgery. CONCLUSION: Bilateral distal chevron osteotomies, associated with lateral soft tissue release, are safe and effective ambulatory procedures. It was found a satisfactory deformity correction in moderate HV. Both patients that underwent unilateral and bilateral procedures had similar clinical and radiological outcomes with no increase in complications or return to normal activity time. With this study it was demonstrated that bilateral chevron osteotomies can be performed as ambulatory procedures.

Trapeziectomy with suture-button suspensionplasty versus ligament reconstruction and tendon interposition: a randomized controlled trial.

The purpose of the present study was to compare the results of patients operated with trapeziectomy and ligament reconstruction and tendon interposition (LRTI) using flexor carpi radialis tendon versus trapeziectomy followed by suspension of the first metacarpal to the second metacarpal using a Mini TightRope® suture button (suture button suspension: SBS). A single-center prospective randomized controlled trial was performed, comparing 37 patients with SBS and 39 with LRTI. All surgeries were performed by the same fellowship-trained hand surgeon. Patients were assessed by an independent observer at 40 months' follow-up. Pre- and postoperative strength, trapezial space ratio (TSR), range of motion, QuickDASH and visual analogue pain score were recorded. Both procedures improved functional parameters of pain, key strength, tip strength and grip strength while maintaining range of motion, without significant differences. In the SBS group, TSR decreased by 17%, compared to 28% in the LRTI group. The mean operative time was shorter in SBS (63 vs 91 minutes; p < 0.0001), as was immobilization time (2 vs 6 weeks; p < 0.0001), and patients resumed normal activity sooner (10 vs 12 week; p = 0.0138) and required less physical therapy (19.3 vs 13.1 weeks; p < 0.0001). We believe that our results are related to the hypothesis suggested by biomechanical studies that revealed better initial load bearing profile and maintenance of trapezial space following serial loading in cadaver models.

Myocardial oedema: pathophysiological basis and implications for the failing heart.

Myocardial fluid homeostasis relies on a complex interplay between microvascular filtration, interstitial hydration, cardiomyocyte water uptake and lymphatic removal. Dysregulation of one or more of these mechanisms may result in myocardial oedema. Interstitial and intracellular fluid accumulation disrupts myocardial architecture, intercellular communication, and metabolic pathways, decreasing contractility and increasing myocardial stiffness. The widespread use of cardiac magnetic resonance enabled the identification of myocardial oedema as a clinically relevant imaging finding with prognostic implications in several types of heart failure. Furthermore, growing experimental evidence has contributed to a better understanding of the physical and molecular interactions in the microvascular barrier, myocardial interstitium and lymphatics and how they might be disrupted in heart failure. In this review, we summarize current knowledge on the factors controlling myocardial water balance in the healthy and failing heart and pinpoint the new potential therapeutic avenues.

[Novel mutation in long QT syndrome in a patient with prior diagnosis of epilepsy]. / Nova mutação na síndroma de QT Longo em doente com diagnóstico prévio de epilepsia.

Congenital long QT syndrome (LQTS) can present as syncope or seizures, secondary to polymorphic ventricular tachycardia, mimicking a primary seizure disorder. In patients treated with an implantable cardioverter-defibrillator (ICD), the recurrence of arrhythmias with subsequent frequent therapeutic shocks may cause adverse reactions, which can be psychogenic. We report the case of a 22-year-old woman with syncope and seizures who was diagnosed in childhood as epileptic and in whom LQTS was diagnosed only in adulthood. Beta-blocker therapy failed and an ICD was implanted. However, as arrhythmias persisted, left cardiac sympathetic denervation was performed. After surgery, three-month follow-up showed a significant reduction in arrhythmias. The genetic study identified a heterozygous mutation, c.1817 C>T p.S606F, on the KCNH2 gene that has not previously been reported in the literature. We also report the rare occurrence of an electrical storm in the course of H1N1 infection. This case illustrates the difficulties in the diagnosis and treatment of LQTS. The possibility of a common genetic basis for arrhythmic diseases and epilepsy is discussed.

Pinckney fracture: do not underestimate trauma of the distal phalanx of the hallux.

Toe injuries are common in the emergency department and most of them are treated conservatively. In some circumstances, these injuries can present as a physeal fracture with concomitant soft-tissue injury affecting the nail bed and resulting in a hidden open fracture. To adequately treat these patients, a high index of suspicion is needed to diagnose and treat the open fractures and to prevent complications such as infection, osteomyelitis, malunion and premature physeal arrest.We report a case of a patient that was admitted to the hospital with a Salter-Harris type I fracture of the distal phalanx of the hallux. After confirming the diagnosis, antibiotic treatment was started and the fracture was reduced and fixed.The literature on this entity is sparse and most of the management protocols are based on its hand equivalent-the Seymour fracture, emphasising the low threshold for treating these lesions as an open fracture.

Assessing the Compressive and Impact Behavior of Plastic Safety Toe Caps through Computational Modelling.

Toe caps are one of the most important components in safety footwear, but have a significant contribution to the weight of the shoe. Efforts have been made to replace steel toe caps by polymeric ones, since they are lighter, insulated and insensitive to magnetic fields. Nevertheless, polymeric solutions require larger volumes, which has a negative impact on the shoe's aesthetics. Therefore, safety footwear manufacturers are pursuing the development of an easy, low-cost and reliable solution to optimize this component. In this work, a solid mechanics toolbox built in the open-source computational library, OpenFOAM®, was used to simulate two laboratory standard tests (15 kN compression and 200 J impact tests). To model the polymeric material behavior, a neo-Hookean hyper-elasto-plastic material law with J2 plastic criteria was employed. A commercially available plastic toe cap was characterized, and the collected data was used for assessment purposes. Close agreements, between experimental and simulated values, were achieved for both tests, with an approximate error of 5.4% and 6.8% for the displacement value in compression and impact test simulations, respectively. The results clearly demonstrate that the employed open-source finite volume computational models offer reliable results and can support the design of toe caps for the R&D footwear industry.

Validation of the Ottawa ankle rules: Strategies for increasing specificity.

INTRODUCTION: The majority of patients with ankle injuries undergo radiological examinations of the foot, ankle or both. The objective of this study was in the first place to validate the Ottawa Ankle Rules (OARs) for the population of our centre. Secondly, an attempt was made to identify parameters that contribute to improve the specificity of the method, with a view to reduce the need for patients to be exposed to radiation as well as optimizing the expenses of the Emergency Ward (EW). MATERIALS AND METHODS: This was a prospective study conducted during a 9-month period. The study population included 148 patients, in 54 (36%) of the patients a fracture was present on the exams performed. Patients were submitted to a sequential protocol in the EW with a form completion, evaluation of OARs, application of the Visual Analog Pain Scale (VAS) and radiographic exams. RESULTS: We found a sensitivity of OARs in ankle injuries of 100%, specificity of 26% and in midfoot injuries of 100% and 62% respectively. All patients with fractures had a VAS of 5 or more points in any of the tested sites. With the VAS criterium, we found a significant increase of global specificity (38% vs 15%), as well as when applied only to the ankle (26% to 47%) or to midfoot trauma (62% to 67%). In both, there would have been a 100% reduction of CT scans. Patients with a fracture or with fractures who required surgical treatment had a mean VAS significantly higher than patients with no fracture or fractures submitted to conservative treatment respectively. Although there was a lower percentage of fractures in the group of injuries in Work Accidents (31% vs 37% Sports Activity and 38% Leisure Activity), there was a statistically significant increase in the sum of average VAS in Accidents at Work vs Leisure Activities and vs Sports Activities. CONCLUSION: We seek to confirm the usefulness of OARs for our population and we investigated strategies to further reduce the need for unnecessary radiographs. The introduction of parameters for grading pain and adapting to the context of the accident seem promising.

Towards Customized Footwear with Improved Comfort.

A methodology enabling the customization of shoes for comfort improvement is proposed and assessed. For this aim, 3D printed graded density inserts were placed in one of the critical plantar pressure zones of conventional insoles, the heel. A semi-automated routine was developed to design the 3D inserts ready for printing, which comprises three main stages: (i) the definition of the number of areas with different mesh density, (ii) the generation of 2D components with continuous graded mesh density, and (iii) the generation of a 3D component having the same 2D base mesh. The adequacy of the mesh densities used in the inserts was previously assessed through compression tests, using uniform mesh density samples. Slippers with different pairs of inserts embedded in their insoles were mechanically characterized, and their comfort was qualitatively assessed by a panel of users. All users found a particular pair, or a set, of prototype slippers more comfortable than the original ones, taken as reference, but their preferences were not consensual. This emphasizes the need for shoe customization, and the usefulness of the proposed methodology to achieve such a goal.

Electrical storm induced by H1N1 A influenza infection.

Pandemic H1N1 influenza A virus is spreading worldwide. We report a case of electrical storm during H1N1 influenza A infection in a patient with congenital long-QT syndrome (LQTS) that was previously stable on beta-blocker therapy. Possible causes for the association of A flu and LQTS recurrent ventricular arrhythmias are discussed.

Coronary artery vasospasm and acute myocarditis: a rare association.

Coronary vasospasm is one cause of chest pain in patients with acute myocarditis. This is a rare association, with few cases reported in the literature. The authors describe a case of acute myocarditis in which presentation mimicked acute myocardial infarction. During hospitalization severe angina recurred twice, accompanied by transient ST-segment elevation in different locations. The hypothesis of coronary vasospasm is discussed. The role of cardiac magnetic resonance imaging in this context is highlighted.

Dispersion of Graphite Nanoplates in Polypropylene by Melt Mixing: The Effects of Hydrodynamic Stresses and Residence Time.

This work combines experimental and numerical (computational fluid dynamics) data to better understand the kinetics of the dispersion of graphite nanoplates in a polypropylene melt, using a mixing device that consists of a series of stacked rings with an equal outer diameter and alternating larger and smaller inner diameters, thereby creating a series of converging/diverging flows. Numerical simulation of the flow assuming both inelastic and viscoelastic responses predicted the velocity, streamlines, flow type and shear and normal stress fields for the mixer. Experimental and computed data were combined to determine the trade-off between the local degree of dispersion of the PP/GnP nanocomposite, measured as area ratio, and the absolute average value of the hydrodynamic stresses multiplied by the local cumulative residence time. A strong quasi-linear relationship between the evolution of dispersion measured experimentally and the computational data was obtained. Theory was used to interpret experimental data, and the results obtained confirmed the hypotheses previously put forward by various authors that the dispersion of solid agglomerates requires not only sufficiently high hydrodynamic stresses, but also that these act during sufficient time. Based on these considerations, it was estimated that the cohesive strength of the GnP agglomerates is in the range of 5-50 kPa.

The role of membranous urethral afferent autonomic innervation in the continence mechanism after nerve sparing radical prostatectomy: a clinical and prospective study.

PURPOSE: We evaluated the somatic and autonomic innervation of the pelvic floor and rhabdosphincter before and after nerve sparing radical retropubic prostatectomy using neurophysiological tests and correlated findings with clinical parameters and urinary continence. MATERIALS AND METHODS: From February 2003 to October 2005, 46 patients with prostate cancer were enrolled in a controlled, prospective study. Patients were evaluated before and 6 months after nerve sparing radical retropubic prostatectomy using the UCLA-PCI urinary function domain and neurophysiological tests, including somatosensory evoked potential, and the pudendo-urethral, pudendo-anal and urethro-anal reflexes. Clinical parameters and urinary continence were correlated with afferent and efferent innervation of the membranous urethra and pelvic floor. We used strict criteria to define urinary continence as complete dryness with no leakage at all, not requiring any pads or diapers and with a UCLA-PCI score of 500. Patients with a sporadic drop of leakage, requiring up to 1 pad daily, were defined as having occasional urinary leakage. RESULTS: Two patients were excluded from study due to urethral stricture postoperatively. We evaluated 44 patients within 6 months after surgery. The pudendo-anal and pudendo-urethral reflexes were unchanged postoperatively (p = 0.93 and 0.09, respectively), demonstrating that afferent and efferent pudendal innervation to this pelvic region was not affected by the surgery. Autonomic afferent denervation of the membranous urethral mucosa was found in 34 patients (77.3%), as demonstrated by a postoperative increase in the urethro-anal reflex sensory threshold and urethro-anal reflex latency (p <0.001 and 0.0007, respectively). Six of the 44 patients used pads. One patient with more severe leakage required 3 pads daily and 23 showed urinary leakage, including 5 who needed 1 pad per day and 18 who did not wear pads. Afferent autonomic denervation at the membranous urethral mucosa was found in 91.7% of patients with urinary leakage. Of 10 patients with preserved urethro-anal reflex latency 80% were continent. CONCLUSIONS: Sensory and motor pudendal innervation to this specific pelvic region did not change after nerve sparing radical retropubic prostatectomy. Significant autonomic afferent denervation of the membranous urethral mucosa was present in most patients postoperatively. Impaired membranous urethral sensitivity seemed to be associated with urinary incontinence, particularly in patients with occasional urinary leakage. Damage to the afferent autonomic innervation may have a role in the continence mechanism after nerve sparing radical retropubic prostatectomy.

Reproducibility in nerve conduction studies and F-wave analysis.

OBJECTIVE: Reproducibility testing of nerve conduction studies and F-wave latencies in a group of healthy volunteers. METHODS: A total of 32 healthy volunteers underwent sensory and motor nerve conduction studies of the ulnar and tibial nerves, including F-waves, elicited by 32 stimuli, repeated in two different days by the same examiner. RESULTS: The F-wave latencies showed less variability than the other parameters of conduction studies, and, among them, the F-wave mean latency of the tibial nerve has been the one with the higher reproducibility. CONCLUSIONS: F-wave latencies were the parameters with best reproducibility, followed by conduction velocities and amplitudes. SIGNIFICANCE: Our data showed that the F-wave mean latency is a parameter with a high reliability, considering the reproducibility, for sequential studies.

Retrospective study evaluating dose standards for infliximab in patients with rheumatoid arthritis at Hospital Israelita Albert Einstein, São Paulo, Brazil.

We determined, in our surrounding environment, the proportion of patients being treated with infliximab who required a therapeutic scheme escalation (an infliximab dose increase surpassing the level of 3 mg/kg every 8 weeks and/or a decrease on the current between infusions' interval). This was a study of the retrospective analysis of data from the 41 rheumatoid arthritis (RA) patients receiving an infliximab therapy at the Albert Einstein Israelita Hospital, from January 2001 up to December 2005. A questionnaire was applied to these patients, assessing their clinical and laboratory data, adverse events, and individual information regarding the infliximab administration. Therapeutic dose information was available in 68% (28/41) of the RA patients, with 46% of these (13/28) receiving a dose increase, and 30% (8/27) experiencing a shortening of the between infusions' interval. The average final infliximab dose (4.21 mg/kg) was significantly greater than their average initial dose (3.29 mg/kg). The average time intervals between the initial and final infusions, though shortened, were not significantly different. A proportion of 73% (30/41) of these patients demonstrated improvement in at least one of the assessed clinical parameters, and 50% of these patients (15/30) experienced a dose increase, while 20% (6/30) experienced shortening of the between treatments' interval. A total of 20% (8/41) of the original patients experienced adverse events. Although infliximab is effective in the control of RA, dose adjustment and/or shortening of the between treatments' interval is frequently required.

A brief historical note on the classification of nerve fibers.

This is a brief review of the literature focused on the articles that formed the basis for the classification of the nerve fibers. Mention is also made to the origin of the nomenclature of the different motoneurons (alpha, beta and gamma).