Stress corrosion cracking in Al-Zn-Mg-Cu aluminum alloys in saline environments

Copyright 2013 ASM International. This paper was published in Metallurgical and Materials Transactions A, 44A(3), 1230 - 1253, and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack (“pop-in” vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies (E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (~0.8 wt pct), they are typically ranging from 20 to 40 kJ/mol for under- and peak-aged alloys, and based on limited data, around 85 kJ/mol for over-aged tempers. This means that crack propagation in saline environments is most likely to occur by a hydrogen-related process for low-copper-containing Al-Zn-Mg-Cu alloys in under-, peak- and over-aged tempers, and for high-copper alloys in under- and peak-aged tempers. For over-aged high-copper-containing alloys, cracking is most probably under anodic dissolution control. Future stress corrosion studies should focus on understanding the factors that control crack initiation, and insuring that the next generation of higher performance Al-Zn-Mg-Cu alloys has similar longer crack initiation times and crack propagation rates to those of the incumbent alloys in an over-aged condition where crack rates are less than 1 mm/month at a high stress intensity factor

Current trends in surgical treatment of parapneumonic effusions and empyema thoracis

Surgical treatment of complicated parapneumonic effusions and empyema thoracis consists of drainage and obliteration of the pleural space. Two scientific Societies have published guidelines concerning management of empyema thoracis in the near past. American College of Chest Physicians (2000) has defined criteria of high-risk for poor outcome. Parapneumonic effusions which met the criteria of high-risk for poor outcome should undergo at least chest tube drainage, that is however unsuccessful in 25-50% of cases. Intrapleural instillation of fibrinolytics, thoracoscopic drainage and thoracotomy were, according to ACCP experts, accepted modalities of management. According to British Thoracic Society guidelines (2003), surgical treatment should be offered after failure of conservative treatment with antibiotics and chest tube drainage. We have nowadays enough evidence that early thoracoscopic drainage reduces hospitalization, chest tube drainage duration and that is successful initial treatment in 90% of cases. Minimally invasive thoracoscopic drainage can effectively drain loculations, inflammatory intrapleural fluid and gel, obliterate the pleural cavity and achieve strategic position of chest drains. Thoracoscopic drainage is unsuccessful management for organizing empyemas, where decortication is the treatment of choice. Early involvement of thoracic surgeons and early thoracoscopic drainage may effectively change the prognosis and outcome of complicated parapneumonic effusions and empyema thoracis

Surgical treatment of pulmonary metastases. Review of the literature a propos of a case-series of 25 recent cases

Surgery is the optimal treatment for pulmonary metastases from certain extrathoracic tumors (soft tissue sar­comas, colorectal and renal cancer, breast cancer and others) which fulfill some strict criteria, such as control of the primary site, long disease free interval and absence of other extrathoracic metastases (with the exception of hepatic metastases from colorectal cancer that can be also eradicated with surgery). Prolonged survival is expected after metastasectomy (even if repeated metastasectomies are required), if the number of the metastases to be resected is low (<3), if complete eradication of the metastatic deposits can be achieved during surgery and if mediastinal lymph nodes are not involved by the tumor. Limited pulmonary resection with the form of wedge resection or enucleation or typical segmentectomy is the standard surgical in­tervention for pulmonary metastases. Major lung parenchyma resection such as lobectomy, bilobectomy or pneumonectomy at instances required in larger, deeply situated within the lung parenchyma, metastases. Formal thoracotomy is the access of choice, while thoracoscopic resection can be applied in selected patients with solitary, peripherally located metastases. Enucleation of the metastatic deposits can be performed using the cautery or preferably using the new generation Nd:YAG lasers. Sparing lung parenchyma is crucial during pulmonary metastasectomy

Delayed diagnosis of right ventricle perforation after blind needle pericardiocentesis

A case of right ventricle perforation in a 63-year old man after blind needle pericardiocentesis for pericardial effusion is presented, focusing on the delayed diagnosis of this serious complication. During surgical repair, the pigtail catheter was found to enter the right ventricle with its tip resting within the pulmonary artery

Infection of the residual pleural space fifty-nine years after artificial pneumothorax for pulmonary tuberculosis

A 79-year old man with serious comorbidities developed empyema of the residual pleural space that was the sequelae of collapse therapy with artificial pneumothorax performed 59 years ago for pulmonary tuberculosis. Drainage of the infected pleural space through open-window thoracostomy resulted in reversal of systemic toxicity and full recovery

Chest Wall Hydatidosis as the Unique Location of the Disease: Case Report and Review of the Literature

The chest wall is a rare location of secondary hydatidosis, but secondary hydatidosis may occur from the rupture of a lung cyst, from a liver cyst invading the diaphragm into the pleural cavity, following previous thoracic surgery for hydatidosis, or by hematogenous spread. This report describes a case of chest wall hydatidosis, which was the primary disease site in the patient, who had no previous history or current disease (hydatidosis) at other sites. The cyst invaded and partially destroyed the 9th and 10th ribs and the 10th thoracic vertebra, and protruded outside the pleural cavity through the 9th intercostal space. Preoperative albendazole administration for 10 days, surgical resection of the disease through a posterolateral thoracotomy incision, and postoperative albendazole treatment resulted in a cure with no evidence of local recurrence or disease at other sites in four years of follow-up

Current status of surgical treatment for pectus excavatum deformity

Pectus excavatum is the commonest anterior chest wall deformity which is the result of overgrowth and elon­gation of costal cartilages that push the normal sternum in. The deformity has serious pshychologic impact and limits the exercise tolerance of the patient, because of displacement of the heart within the left hemithorax. Repair of pectus excavatum is performed by the classical Ravich technique or the minimally invasive Nuss repair. The Ravich operation consists of resection of the deformed cartilages, bending the sternum in its normal position and maintenance of the sternum in the correct position by using a metal bar or a strong synthetic mesh. The Nuss procedure involves the thoracoscopic placement of a pre-formed curved metal bar behind the sternum which rises the sternum to the desired position. The selection of the technique depends on the age of the patient and the degree and symmetry of the deformity. The Nuss technique is suitable for children between 5 and 15 years old who have flexible chest wall and symmetric deformities, while the Ravich procedure is indicated in young adults and asymmetric forms. Indeed, the Nuss technique still undergoes modifications to become safer and simpler and further it needs expertise and special equipment

Tumours of the thymus: a cohort study of prognostic factors from the European Society of Thoracic Surgeons database

OBJECTIVES A retrospective database was developed by the European Society of Thoracic Surgeons, collecting patients submitted to surgery for thymic tumours to analyse clinico-pathological prognostic predictors. METHODS A total of 2151 incident cases from 35 institutions were collected from 1990 to 2010. Clinical-pathological characteristics were analysed, including age, gender, associated myasthenia gravis stage (Masaoka), World Health Organization histology, type of thymic tumour [thymoma, thymic carcinoma (TC), neuroendocrine thymic tumour (NETT)], type of resection (complete/incomplete), tumour size, adjuvant therapy and recurrence. Primary outcome was overall survival (OS); secondary outcomes were the proportion of incomplete resections, disease-free survival and the cumulative incidence of recurrence (CIR). RESULTS A total of 2030 patients were analysed for OS (1798 thymomas, 191 TCs and 41 NETTs). Ten-year OS was 0.73 (95% confidence interval 0.69-0.75). Complete resection (R0) was achieved in 88% of the patients. Ten-year CIR was 0.12 (0.10-0.15). Predictors of shorter OS were increased age (P < 0-001), stage [III vs I HR 2.66, 1.80-3.92; IV vs I hazard ratio (HR) 4.41, 2.67-7.26], TC (HR 2.39, 1.68-3.40) and NETT (HR 2.59, 1.35-4.99) vs thymomas and incomplete resection (HR 1.74, 1.18-2.57). Risk of recurrence increased with tumour size (P = 0.003), stage (III vs I HR 5.67, 2.80-11.45; IV vs I HR 13.08, 5.70-30.03) and NETT (HR 7.18, 3.48-14.82). Analysis using a propensity score indicates that the administration of adjuvant therapy was beneficial in increasing OS (HR 0.69, 0.49-0.97) in R0 resections. CONCLUSIONS Masaoka stages III-IV, incomplete resection and non-thymoma histology showed a significant impact in increasing recurrence and in worsening survival. The administration of adjuvant therapy after complete resection is associated with improved surviva

Ectopic paraesophageal mediastinal parathyroid adenoma, a rare cause of acute pancreatitis

BACKGROUND: The manifestation of primary hyperparathyroidism with acute pancreatitis is a rare event. Ectopic paraesophageal parathyroid adenomas account for about 5%–10% of primary hyperparathyroidism and surgical resection results in cure of the disease. CASE PRESENTATION: A 71-year-old woman was presented with acute pancreatitis and hypercalcaemia. During the investigation of hypercalcemia, a paraesophageal ectopic parathyroid mass was detected by computerized tomography (CT) scan and (99m)Tc sestamibi scintigraphy. The tumor was resected via a cervical collar incision and calcium and parathormone tumor levels returned to normal within 48 hours. CONCLUSIONS: Acute pancreatitis associated with hypercalcaemia should pose the suspicion of primary hyperparathyroidism. Accurate preoperative localization of an ectopic parathyroid adenoma, by using the combination of (99m)Tc sestamibi scintigraphy and CT scan of the neck and chest allows successful surgical treatment

A rare tumoral combination, synchronous lung adenocarcinoma and mantle cell lymphoma of the pleura

<p>Abstract</p> <p>Background</p> <p>Coexistence of adenocarcinoma and mantle cell lymphoma in the same or different anatomical sites is extremely rare. We present a case of incidental discovery of primary lung adenocarcinoma and mantle cell lymphoma involving the pleura, during an axillary thoracotomy performed for a benign condition.</p> <p>Case presentation</p> <p>A 73-year old male underwent bullectomy and apical pleurectomy for persistent pneumothorax. A bulla of the lung apex was resected en bloc with a scar-like lesion of the lung, which was located in proximity with the bulla origin, by a wide wedge resection. Histologic examination of the stripped-off parietal pleura and of the bullectomy specimen revealed the synchronous occurrence of two distinct neoplasms, a lymphoma infiltrating the pleura and a primary, early lung adenocarcinoma. Immunohistochemical and fluorescence in situ hybridization assays were performed. The morphologic, immunophenotypic and genetic findings supported the diagnosis of primary lung adenocarcinoma (papillary subtype) coexisting with a non-Hodgkin, B-cell lineage, mantle cell lymphoma involving both, visceral and parietal pleura and without mediastinal lymph node involvement. The neoplastic lymphoid cells showed the characteristic immunophenotype of mantle cell lymphoma and the translocation t(11;14). The patient received 6 cycles of chemotherapy, while pulmonary function tests precluded further pulmonary parenchyma resection (lobectomy) for his adenocarcinoma. The patient is alive and without clinical and radiological findings of local recurrence or distant relapse from both tumors 14 months later.</p> <p>Conclusion</p> <p>This is the first reported case of a rare tumoral combination involving simultaneously lung and pleura, emphasizing at the incidental discovery of the two coexisting neoplasms during a procedure performed for a benign condition. Any tissue specimen resected during operations performed for non-tumoral conditions should be routinely sent for pathologic examination.</p