Effects of pipe angular velocity and oven configuration on tube temperature distribution in the radiative heating of PVC pipes

Abstract Several manufacturing processes in polymer industry aim at obtaining products by deforming preforms or sheets after a heating process. A thorough knowledge of the operating parameters of such heating processes is fundamental to fulfill the often high production requirements with the least energy consumption and to avoid unacceptable defects in the final product. A common example of such an application is the end-forming process of polyvinyl chloride (PVC) tubes, which are enlarged at one end in order to allow pipes connections. The heating phase which comes before the deformation process is usually carried out in ovens equipped with short wave infrared lamps; to ensure uniform heating, pipes rotate with a given angular velocity, which represents a fundamental parameter for the success of the whole manufacturing process. In this work, a transient analysis of the radiative heat exchange between rotating PVC pipes and infrared lamps in an oven for end-forming process has been conducted by means of a finite element model, in order to investigate the influence of cylinder angular velocity on the temperature distribution in the tube. Local view factors have been calculated for different oven configurations and have been expressed as a function of angular velocity, allowing pipe rotation to be simulated as a time-dependent boundary condition, instead of using a moving mesh. Simulations were carried out for different tubes geometries and angular velocities and results were compared with the case of a uniformly irradiated tube in terms of temperature displacement. For a given oven configuration, the results obtained by the numerical model can be used to find a critical angular velocity over which further increase does not lead to appreciable improvements in temperature evenness. The effect of the lamps' relative position was also investigated, showing a significant influence on critical angular velocities obtained. The model realized represents a potential tool to characterize the end-forming process in terms of critical angular velocity, leading to reductions in machine set-up time and product waste due to thermal failure

Thermal characterization of the end-forming process of PVC pipes: influence of the number of lamps on critical angular velocities

Abstract The end-forming, or belling, of plastic pipes allows them to be joined together to form longer ducts. The first stage of the process entails softening the pipe wall through heating, and defines the properties of the final product. Because of the very low value of thermal conductivity of plastics and to speed heating up, the pipes are placed in ovens whose walls are lined with infra-red short-wave (SW) lamps. The radiation emitted partly penetrates the pipe wall, quickening the process. The heating elements have a straight configuration, and can only be laid axially flush over the oven's wall, the pipes, therefore, must rotate to obtain a circumferentially uniform heating and avoid damage. The threshold speed to avoid scorching while exceeding a desired temperature over the thickness of the pipe wall is defined as "critical angular velocity" and is strictly dependent on pipe geometry and oven characteristics such as the number and layout of lamps. The Authors have already investigated the problem extensively, as is well documented in the literature, yet one aspect still remains to be studied, namely the influence of the number of lamps on the heat flux distribution over the pipe's perimeter and on the critical velocity. In this work, the issue is investigated thoroughly using the same approach previously adopted and recalled in its main aspects in the paper. It is found that even a significant reduction in the number of lamps does not increase threshold velocities to technically unfeasible values. A non-negligible reduction in costs can therefore be achieved without significant impact on the process outcomes

P2X7 mRNA expression in non-small cell lung cancer: MicroRNA regulation and prognostic value

The human P2X7 receptor is significant and exhibits several functions in neoplasia. At present, little is known with regard to its regulation. P2X7 expression may be regulated post-transcriptionally and putative microRNA (miRNA) binding sites are considered to be involved. The aim of this study was to determine whether miRNAs (miR-21, let-7 g and miR-205) regulate P2X7 mRNA stability. In addition, the impact of P2X7 expression in patients with non-small cell lung cancer (NSCLC) was investigated. P2X7 mRNA and mature Let-7 g, miR-21, and miR-205 expression levels were quantified in 96 NSCLC cases using quantitative reverse transcription polymerase chain reaction. In all samples, epidermal growth factor receptor and K-Ras mutational analysis was also performed. Samples with low P2X7 expression were found to exhibit a higher fold change in miR-21 expression when compared with samples exhibiting high P2X7 expression. Significantly higher miR-21 expression was observed in the tumors of NSCLC patients with a K-Ras mutation when compared with patients who had K-Ras wild-type tumors (P=0.003). Additionally, to evaluate the association between P2X7 expression and prognosis in NSCLC patients, survival analysis was performed using the Kaplan-Meier method. A significant difference in the progression-free survival and overall survival in the NSCLC patients with high P2X7 expression was identified, when compared with that of patients with low expression (P=0.03 and P=0.02, respetively). Therefore, we hypothesized that high levels of miR-21 expression in NSCLC patients with K-Ras mutations may be regulated by a complex circuit, including P2X7 downregulation and together these processes may promote tumor progression

Hypertermic Intrathoracic Chemotherapy (HITHOC) for thymoma: a narrative review on indications and results

Objective: With this narrative review, we retraced the history of hypertermic intrathoracic chemotherapy (HITHOC) since the beginning, analyzing literature on operative technique, feasibility and efficacy of this treatment. Moreover, we report the fifteen-year experience of our center in this relatively new technique, for what concerns both early postoperative results and long-term oncological outcomes. Background: Thymomas are frequently misdiagnosed and recognized in advanced stage, often with pleural dissemination, especially when not associated to Myasthenia Gravis that allows an early diagnosis during the initial assessment. Moreover, the natural history of locally advanced thymoma is characterized by a high rate of pleural or pericardial relapses. Surgery has always been considered a milestone in thymoma's treatment, even in case of serous dissemination or relapses, although his role as exclusive therapy does not guarantee an acceptable local disease control. In case of disseminated disease, different multidisciplinary protocols have been experimented, from chemotherapy to radiation therapy, alone or associated to surgery, in order to increase overall and disease-free survival, but the breakthrough happened in the early 90s with the introduction of HITHOC following surgery. Combination of surgery and HITHOC resulted in less toxic than systemic chemotherapy and providing a good local disease control in patients with stage IVa thymomas or thymoma's pleural recurrences. Methods: We searched PubMed for relevant literature, up to January 2020, on hypertermic intrapleural chemotherapy for thymomas (TPR or DNT), selecting only those reporting information about HITHOC protocol used, postoperative course and oncological outcomes. Conclusions: HITHOC is a safe and feasible procedure, with a very low complication rate and negligible systemic effects of chemotherapeutic agents, effective in controlling both TPR and DNT, in particular as regards local disease-free survival. Keywords: Hypertermic intrathoracic chemotherapy (HITHOC); thymoma; intracavitary chemotherapy; hyperthermia; redo-surgery

Chest wall reconstruction with implantable cross-linked porcine dermal collagen matrix: Evaluation of clinical outcomes

Objectives: The aim of the study is to evaluate clinical applications, safety, and effectiveness of a porcine-derived acellular cross-linked dermal matrix biological mesh in chest wall reconstruction. Methods: We retrospectively analyzed a prospective multicenter database of chest wall reconstructions using a biological mesh in adult patients undergoing operation between October 2013 and December 2020. We evaluated preoperative data, type of resection and reconstruction, hospitalization, 30-day morbidity and mortality, and overall survival. Results: A total of 105 patients (36 women [34.2%]; mean age, 57.0 +/- 16.1 years; range, 18-90 years) were included, they have admitted for: primary chest wall tumor (n = 52; 49.5%), secondary chest wall tumor (n = 29; 27.6%), lung hernia (n = 12; 11.4%), trauma (n =10; 9.6%), and infections (n = 2; 1.9%). The surgical sites were preoperatively defined as at high risk of infection in 28 patients (26.7%) or as infected in 16 (15.2%) patients. Thirty-days morbidity was 30.5% (n = 32 patients); 14 patients (13.3%) had postoperative complications directly related to chest wall surgical resection and/or reconstruction. We experienced no 30-day mortality; 1-year and 2-year mortality was 8.4% and 16.8%, respectively. Conclusions: Biological mesh represents a valuable option in chest wall reconstruction even when surgical sites are infected or at high-risk of infections. This mesh shows low early and late postoperative complication rates and excellent long-term stability

Prognostic role of TPL2 in early‑stage non‑small cell lung cancer

Non‑small cell lung cancer (NSCLC) accounts for ~70% of all lung cancer‑associated mortalities worldwide. The serine/threonine protein kinase tumor progression locus 2 [TPL2/MAP3 kinase 8 (MAP3K8)] may impact oncogenic events; however the role of TPL2 in lung carcinogenesis remains unclear. The present study was focused on the potential prognostic role of TPL2 in 101 patients with early‑stage NSCLC. Since TPL2 is a potential target of miR‑21, the association between TPL2 and miR‑21 expression was also examined. TPL2 and miR‑21 mRNA expression was quantified using reverse transcription quantitative polymerase chain reaction (RT‑qPCR). TPL2 protein levels were evaluated by immunohistochemistry (IHC). The present study identified that the mRNA expression of TPL2 was low in 52/101 (51%) cases and high in 49/101 (49%) cases. IHC analysis of TPL2 protein expression often demonstrated identical mRNA results. No statistically significant associations were observed between the mRNA expression of TPL2 and the predominant clinicopathological characteristics of the patients with NSCLC, as well as identifying no association between TPL2 and miR‑21. TPL2 mRNA expression was significantly higher in patients with NSCLC with good prognosis (disease‑free interval P=0.009; overall survival P=0.024), when compared with those of poor prognosis. Focusing on the difference in mRNA expression of TPL2 among the adenocarcinomas in affected patients, TPL2 was more highly expressed in lepidic adenocarcinomas compared with in the other subtypes (P=0.012). The present study is the first examination, to the best of our knowledge, of TPL2 in early‑stage NSCLC in relation to miR‑21, and in different adenocarcinoma subtypes. Future studies must clarify the mechanism by which TPL2 is involved in lung carcinogenesis due to its important translational implications

Malignant pleural mesothelioma and mesothelial hyperplasia: A new molecular tool for the differential diagnosis

Malignant pleural mesothelioma (MPM) is a rare asbestos related cancer, aggressive and unresponsive to therapies. Histological examination of pleural lesions is the gold standard of MPM diagnosis, although it is sometimes hard to discriminate the epithelioid type of MPM from benign mesothelial hyperplasia (MH). This work aims to define a new molecular tool for the differential diagnosis of MPM, using the expression profile of 117 genes deregulated in this tumour. The gene expression analysis was performed by nanoString System on tumour tissues from 36 epithelioid MPM and 17 MH patients, and on 14 mesothelial pleural samples analysed in a blind way. Data analysis included raw nanoString data normalization, unsupervised cluster analysis by Pearson correlation, non-parametric Mann Whitney U-test and molecular classification by the Uncorrelated Shrunken Centroid (USC) Algorithm. The Mann-Whitney U-test found 35 genes upregulated and 31 downregulated in MPM. The unsupervised cluster analysis revealed two clusters, one composed only of MPM and one only of MH samples, thus revealing class-specific gene profiles. The Uncorrelated Shrunken Centroid algorithm identified two classifiers, one including 22 genes and the other 40 genes, able to properly classify all the samples as benign or malignant using gene expression data; both classifiers were also able to correctly determine, in a blind analysis, the diagnostic categories of all the 14 unknown samples. In conclusion we delineated a diagnostic tool combining molecular data (gene expression) and computational analysis (USC algorithm), which can be applied in the clinical practice for the differential diagnosis of MPM

Diaphragm and lung-preserving surgery with hyperthermic chemotherapy for malignant pleural mesothelioma: A 10-year experience

Background: The best surgical treatment for malignant pleural mesothelioma is still under a debate, but recent evidence points toward a less-invasive approach to reduce morbidity and mortality. We reported our 10-year experience of a limited surgical approach associated with hyperthermic intrathoracic chemotherapy (HITHOC). Material and Methods: Between 2005 and 2014, patients with epithelioid or biphasic malignant pleural mesothelioma were treated with lung-diaphragm-pericardium-sparing pleurectomy associated with double-drug HITHOC; at least 3 cycles of adjuvant chemotherapy were then administered. The primary outcome examined was the feasibility of the procedure, whereas secondary outcomes were overall survival and disease-free interval. Results: Among 49 patients, 41 were male. Median age was 68 years (35-76 years). Histology was epithelioid in 43 cases. Pathologic stage I, II, III, and IV occurred in 12, 14, 20, and 3 cases, respectively. No intraoperative complications or postoperative mortality occurred, whereas morbidity rate was 46.9%. Median hospital stay was 8 days (5-45 days). Actuarial median overall survival was 22 months and a 1-, 2-, and 5-year survival accounted for 79.6%, 45.7%, and 9.9%, respectively. Disease-free survival after surgery was 62%, 37.5%, and 18.5% at 1, 2, and 5 years, respectively. Risk factors analysis for overall survival confirmed a significant role for early stages, epithelioid histology, and fibrinogen serum levels. Conclusions: Cytoreductive surgery associated with HITHOC and adjuvant chemotherapy appears feasible and safe, with no mortality and low morbidity. Preserving lung and diaphragmatic function might warrant an acceptable long-term outcome