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Friction stir additive manufacturing (FSAM) is a variant of sheet lamination additive manufacturing used to produce large, near-net-shaped 3D parts. Unlike traditional friction stir lap welding, FSAM introduces a new plate to one that is already joined, with the effective area limited to the nugget zone. The present study focuses on exploring the microstructure and microhardness around the nugget zone in a five-plate AA 7075-T651 laminate synthesized at 1000 rpm and 35 mm/min. Microhardness increased vertically in the weldment NZ, reaching 143 HV in the top layer with 2.0 µm fine equiaxed grains. The grains on the advancing and retreating sides were coarser compared to the nugget zone. A W-shaped microhardness profile appeared across layer interfaces. These findings contribute significantly to advancing the FSAM technique, particularly in manufacturing multi-layered, multi-pass laminates. [ABSTRACT FROM AUTHOR]

Laminar composites have widespread applications in the automotive and aircraft industry. This research was aimed to investigate the suitability of fused deposition modeling to produce multi-material laminar composites. Composites comprising of two dissimilar laminates, named as hybrid composites, were printed from acrylonitrile butadiene styrene filament and carbon fiber-reinforced polylactic acid filament (a composite filament) by varying different printing parameters. Tensile tests were conducted to examine the mechanical performance of the produced composite sheet. A detailed analysis of the results revealed that a high ultimate tensile strength is primarily achieved by setting low values of printing speed, layer height, and clad ratio while high elongation is obtained by employing low printing speed, medium layer height, and high clad ratio. The optimum printing conditions were sought out through desirability function with an objective to simultaneously enhance all the considered properties. Further, the composite sheet exhibited a reasonably good combination of tensile properties as compared to its monolithic constituent sheets. Based on the results, it is concluded that the bi-material laminating approach employed herein can produce printed structures with desired properties. [ABSTRACT FROM AUTHOR]

Bronchogenic cysts of the mediastinum are congenital cystic lesions that can occur in infants, children, and also adults. These are benign in nature and in many instances, asymptomatic. The maximum size of a bronchogenic cyst of mediastinum found in literature is 15 cm. We present a case of a 21 cm large mediastinal bronchogenic cyst. [ABSTRACT FROM AUTHOR]

Objective: To determine the outcome of thymectomy in patients with myasthenia gravis and safety of median sternotomy approach., Methodology: An observational descriptive study was conducted in the department of thoracic surgery JPMC from February 2005 to January 2009. Twenty-two patients having persistent generalized or ocular myasthenia gravis referred to our department by neurologists and general physicians, partially or not responding to medical treatment with or without thymoma, were included in the study. Those who were not fit for anaesthesia were excluded. Preoperatively 2 to 3 sessions of plasmapheresis were done and each patient was given anti myasthenia gravis treatment. Clinical staging was done by Modified Osserman classification. Median sternotomy approach was used. Outcome was assessed on the basis of remission of disease in different Osserman groups. All patients were followed for a minimum of 6 months., Results: Out of 22 patients, 16 (72.7%) were females and 6 (27.2%) males. Mean age at presentation was 35.2 +/- 14.5 years. Mean duration of symptoms was 1.5 +/- 1.2 years. A total of 4 (18.1%) patients with myasthenia gravis had thymoma and histopathology of 18 (81.9%) patients showed thymic hyperplasia. Remission was seen in most grades of Osserman. The best response was seen in Grade I where all patients achieved remission. Most patients in Grade II A and II B were benefited. The only patient in Grade III had no improvement of symptoms. No patient in Grade IV underwent thymectomy. Overall 86.3% had a positive outcome on basis of remission and improvement., Conclusion: Thymectomy by median sternotomy is safe and effective with more favourable outcomes for patients of myasthenia gravis not responding to medical treatment.

Objective: To compare the clinical presentation and results of pulmonary resection in simple and complex aspergilloma of the lung., Study Design: Observational study., Place and Duration of Study: The Department of Thoracic Surgery, Jinnah Postgraduate Medical Centre, Karachi, from January 2003 to December 2008., Methodology: Fifty-one adult patients with unilateral aspergilloma lung were included in this study. Patients were divided into two groups: A (simple aspergilloma-SA, n=14) and B (complex aspergilloma-CA, n=37), based on the radiological and operative characteristics of the cavitatory lesion and the presence or absence of extensive adhesions with the chest wall. Suitability for resection was assessed with arterial gases, pulmonary function tests and echocardiogram. Results were compared using Fishers exact test., Results: Recurrent hemoptysis was the predominant symptom in both the groups. Exertional dyspnea (A=21.4%; B=56.8%; p=0.03), chest pain (A=21.4%; B=59.5%; p=0.027), cough (A=35.7%; B=70.3%; p < 0.05) and postoperative complications like residual pleural space A=14.2%; B=54%; p=0.013) and pleural collection (A=7.1%; B=37.8%; p=0.041) were predominant in group B. Lobectomy was the most common procedure performed in group B (A=28.6%; B=59.5%), while wedge excision was performed in the majority of patients in group A (A=42.9%; B=29.7%). Recurrence of aspergilloma was seen in 3 patients (8.1%) in group B only. Total number of early and late complications in SA and CA were 7, and 60, respectively. Early mortality was 8.1% and 0.0% in group B and group A, [corrected] respectively (p=0.552). The overall mortality was 5.4%., Conclusion: Symptoms were more frequently associated with CA as compared to SA. Surgery for CA was associated with low mortality but significant morbidity, whereas SA had low postoperative morbidity and no mortality.

Objective: To determine the frequency of survival in patients with thoracic trauma, undergoing Urgent Thoracotomy (UT)., Study Design: Quasi-experimental study., Place and Duration of Study: The study was carried out in the Department of Thoracic Surgery, JPMC, Karachi, from January 2005 to June 2007 (30 months)., Methodology: Fifty two patients, who presented with chest trauma and underwent UT within 48 hours of sustaining thoracic trauma, were included in the study. All patients were assessed by history, physical examination and relevant investigations., Results: A total of 475 patients with acute thoracic trauma needing admission during the study period presented to the Accidents and Emergency Department. Fifty-two (52/475; 10.9%) patients were indicated for UT. The most common indication for UT was massive hemothorax (43/52; 82.6%). The mean age of the patients was 34.36 +/- 11.02 years. There were 22 (42.2%) blunt injuries and 30 (57.8%) penetrating injuries. Road Traffic Accidents (RTA) were the most frequent cause of blunt chest injuries (15 patients; 75%), while firearm injury was the commonest (21 patients; 70%) cause of penetrating chest trauma. Post thoracotomy mortality was 13.3 % (4 out of 30) in patients with penetrating injuries and 18.2% (4 out of 22) in patients with blunt injuries (p < 0.01). Mortality of UT was 15.3 % with survival of 84.7%. Overall survival in 475 patients was 95.58%., Conclusion: Early recognition of treatable injuries and an aggressive approach in management with Urgent Thoracotomy can increase chances of survival of patients suffering from severe chest trauma.

Morgagni's hernia is an uncommon type of diaphragmatic hernia. These patients usually present in childhood but sometimes later in life. We report a case of 75 years old female who presented with epigastric discomfort and vomiting. She was diagnosed as a case of calculous cholecystitis and was treated with antibiotics but was not relieved. Further investigations revealed Morgagni's hernia. She was successfully managed by open surgical technique.