2,955 research outputs found
Estimation of Fatigue Limit of a A356-T6 Automotive Wheel in Presence of Defects
The automotive wheel is a critical safety component in the vehicle and, for such a reason, it has also to meet strict requirements about technological properties. This component is produced by low pressure die casting technique and the casting defects related to the process have to be properly considered having a high effect in decreasing both static and dynamic resistance of the component. Effectively, casting defects like porosities influence the fatigue crack initiation and strongly affect the fatigue life too. One of the most common problem in the real component is the mismatch between the experimental data and literature. In fact, many scientific researches were carried out on small samples produced in a controlled condition and therefore it is difficult to direct transfer the laboratory results to a real cast component with a well-defined shape and different thicknesses.
In the present study, an aluminum alloy A356-T6 wheel was analyzed in order to correlate the fatigue performance taking in to account the casting defects.
The fatigue limit of the component was studied by rotating bending fatigue tests executed on the whole wheels. Microfractographic analyses on the broken wheels were carried out on the fracture surfaces using a Scanning Electron Microscope in order to identify the crack initiation zone: it was recognized that the crack always started from shrinkage porosities. The statistical population of these defects was therefore investigated on samples taken from the wheel in crack nucleation positions of the spoke and the maximum expected defect size on the component was estimated by the statistics of extreme values. The experimental fatigue limit was finally compared with the theoretical value predicted with the Murakamiâs method
Exploring the link between diabetes and pancreatic cancer
Introduction: Epidemiological studies indicate an association between type 2 diabetes and pancreatic cancer but the complex and multidirectional relationship between them remains unclear. Areas covered: We summarized epidemiological evidence on diabetes and pancreatic cancer exploring the time-risk relationship. We described mechanisms linking long-standing diabetes to pancreatic cancer. We discussed pancreatic cancer-associated diabetes and its implication in the early detection of pancreatic cancer. Expert opinion: The markedly increased risk of pancreatic cancer in patients with new-onset diabetes compared with long-standing diabetes indicates a complex and bidirectional connection, with long-standing diabetes being a predisposing factor for pancreatic cancer (increasing the risk of the malignancy 1.5- to 2-fold) and new-onset diabetes an early manifestation of the tumour. Identifying clinical features and biomarkers to distinguish pancreatic cancer-associated diabetes from type 2 diabetes is an important goal to improve management and survival of this cancer. Imaging (MRI) for middle age patients with new-onset diabetes may be considered
A meta-analysis of alcohol drinking and cancer risk
To evaluate the strength of the evidence provided by the epidemiological literature on the association between alcohol consumption and the risk of 18 neoplasms, we performed a search of the epidemiological literature from 1966 to 2000 using several bibliographic databases. Meta-regression models were fitted considering linear and non-linear effects of alcohol intake. The effects of characteristics of the studies, of selected covariates (tobacco) and of the gender of individuals included in the studies, were also investigated as putative sources of heterogeneity of the estimates. A total of 235 studies including over 117â000 cases were considered. Strong trends in risk were observed for cancers of the oral cavity and pharynx, oesophagus and larynx. Less strong direct relations were observed for cancers of the stomach, colon and rectum, liver, breast and ovary. For all these diseases, significant increased risks were found also for ethanol intake of 25âg per day. No significant nor consistent relation was observed for cancers of the pancreas, lung, prostate or bladder. Allowance for tobacco appreciably modified the relations with laryngeal, lung and bladder cancers, but not those with oral, oesophageal or colorectal cancers. This meta-analysis showed no evidence of a threshold effect for most alcohol-related neoplasms. The inference is limited by absence of distinction between lifelong abstainers and former drinkers in several studies, and the possible selective inclusion of relevant sites only in cohort studies. © 2001 Cancer Research Campaign http://www.bjcancer.co
Aspirin and the risk of colorectal and other digestive tract cancers: an updated meta-analysis through 2019
Aspirin has been associated with a reduced risk of colorectal cancer, and possibly of a few other digestive tract cancers. The quantification of risk reduction and the optimal dose and duration of aspirin use for the prevention of colorectal and other digestive tract cancers remains unclear
Risk factors for adenocarcinoma of the cervix: a case-control study.
To assess risk factors for cervical adenocarcinoma data were collected in a case-control study of 39 cases and 409 controls conducted in the greater Milan area. Questions were asked about personal characteristics and habits, gynaecologic and obstetric data, history of lifetime use of oral contraceptives and other female hormones, and general indicators of sexual habits (age at first intercourse and total number of sexual partners). The relative risk of cervical adenocarcinoma increased with number of births and abortions, early age at first birth and early age at first intercourse. These estimates did not materially change after adjustment for the potential reciprocal confounding effect. Further, there was a positive association with overweight, but an apparent association with lower education was not significant. No relationship emerged with oral contraceptive use. Thus, despite the similarities with the epidemiology of squamous cell cancer, reproductive patterns and other factors related to the risk of endometrial cancer (i.e., overweight) seem to play an important role in the risk of adenocarcinoma of cervix uteri
EASL Clinical Practice Guideline : Occupational liver diseases
A variety of chemicals have been linked to occupational liver diseases, including several solvents and mixtures thereof, pesticides, and metals. Workplace exposures have been associated with virtually the entire spectrum of acute and chronic liver diseases. However, their prevalence is inadequately quantified and their epidemiology limited. Occupational liver diseases may result from high accidental or from prolonged lower level exposures. Whereas the former is uncommon and easily recognised, the latter are relatively more frequent but often overlooked because they may display normal values of conventional markers, have an insidious onset and be asymptomatic or be obfuscated and confounded by concurrent conditions. In addition, specific tests of toxicity are not available, histopathology may not be revealing and the assessment of internal dose of chemicals is usually not decisive. Given these circumstances, the diagnosis of these liver disorders is challenging, one of exclusion and often requires an interdisciplinary approach. These recommendations offer a classification of the type of liver injuries associated with occupational exposures \u2013 based in part on the criteria for drug-induced liver injury \u2013 a grading of their severity, and the diagnostic and preventive criteria for chemically induced occupational liver disease
Smoking behaviour, involuntary smoking, attitudes towards smoke-free legislations, and tobacco control activities in the European Union
The six most important cost-effective policies on tobacco control can be measured by the Tobacco Control Scale (TCS). The objective of our study was to describe the correlation between the TCS and smoking prevalence, self-reported exposure to secondhand smoke (SHS) and attitudes towards smoking restrictions in the 27 countries of the European Union (EU27)
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