Investigation of the Thermomechanical Response of Cyclically Loaded NiTi Alloys by Means of Temperature Frequency Domain Analyses

Nickel–Titanium (NiTi) shape memory alloys subjected to cyclic loading exhibit reversible temperature changes whose modulation is correlated with the applied load. This reveals the presence of reversible thermomechanical heat sources activated by the applied stresses. One such source is the elastocaloric effect, accounting for the latent heat of Austenite–Martensite phase transformation. It is, however, observed that when the amplitude of cyclic loads is not sufficient to activate or further propagate this phase transformation, the material still exhibits a strong cyclic temperature modulation. The present work investigates the thermomechanical behaviour of NiTi under such low-amplitude cyclic loading. This is carried out by analysing the frequency domain content of temperature sampled over a time window. The amplitude and phase of the most significant harmonics are obtained and compared with the theoretical predictions from the first and second-order theories of the Thermoelastic Effect, this being the typical reversible thermomechanical coupling prevailing under elastic straining. A thin strip of NiTi, exhibiting a fully superelastic behaviour at room temperature, was investigated under low-stress amplitude tensile fatigue cycling. Full-field strain and temperature distributions were obtained by means of Digital Image Correlation and IR Thermography. The work shows that the full field maps of amplitude and phase of the first three significant temperature harmonics carry out many qualitative information about the stress and structural state of the material. It is, though, found that the second-order theory of the Thermoelastic Effect is not fully capable of justifying some of the features of the harmonic response, and further work on the specific nature of thermomechanical heat sources is required for a more quantitative interpretation

Investigation of the thermomechanical response of cyclically loaded niti alloys by means of temperature frequency domain analyses

Nickel\u2013Titanium (NiTi) shape memory alloys subjected to cyclic loading exhibit reversible temperature changes whose modulation is correlated with the applied load. This reveals the pres-ence of reversible thermomechanical heat sources activated by the applied stresses. One such source is the elastocaloric effect, accounting for the latent heat of Austenite\u2013Martensite phase transfor-mation. It is, however, observed that when the amplitude of cyclic loads is not sufficient to activate or further propagate this phase transformation, the material still exhibits a strong cyclic temperature modulation. The present work investigates the thermomechanical behaviour of NiTi under such low-amplitude cyclic loading. This is carried out by analysing the frequency domain content of temperature sampled over a time window. The amplitude and phase of the most significant harmonics are obtained and compared with the theoretical predictions from the first and second-order theories of the Thermoelastic Effect, this being the typical reversible thermomechanical coupling prevailing under elastic straining. A thin strip of NiTi, exhibiting a fully superelastic behaviour at room temperature, was investigated under low-stress amplitude tensile fatigue cycling. Full-field strain and temperature distributions were obtained by means of Digital Image Correlation and IR Thermography. The work shows that the full field maps of amplitude and phase of the first three significant temperature harmonics carry out many qualitative information about the stress and structural state of the material. It is, though, found that the second-order theory of the Thermoelastic Effect is not fully capable of justifying some of the features of the harmonic response, and further work on the specific nature of thermomechanical heat sources is required for a more quantitative interpretation

HEAT SHOCK PROTEINS AND ULCERATIVE COLITIS: THE START OF A NEW ERA?

We read with great interest the article written by Abou El Azm and coworkers, published in the last issue of the Arab Journal of Gastroenterology [1]. In this article, the authors investigated the molecular expression of heat shock proteins (HSP) 70 and 90 in relation to the grades of inflammation and dysplasia in patients with ulcerative colitis (UC) before and after treatment. In this study, in agreement with other published studies [2–4], the authors not only found a potential role for HSP 70 and HSP 90 for assessment of the activity and prognosis of UC, but also such markers predicted the presence of dysplasia and differentiated it from reactive atypia [1]. HSP had been found not only a marker of active disease, thus considering UC as a ‘‘chaperonopathy by mistake’’, but also show a key role in the psychosocial setting in which inflammatory bowel diseases manifest themselves [5]. Furthermore, they could represent a new diagnostic tool to differentiate the different phenotypes of UC, thus allowing to tailor a targeted approach to better manage UC patients [6]. However, some unresolved issues still remain about the potential roles of HSP in both the acute and the longstanding disease. First, it should be interesting to assess the role of HSP in the infections associated to UC flares, like Clostridium difficile and Cytomegalovirus (CMV) infections. In fact, HSP could be investigated as a further marker of inflammation in case of severe and steroid-refractory disease; with regard to CMV infection, mucosal levels of HSP could differentiate when CMV plays a role of direct pathogen or when it represents merely a ‘‘silent bystander’’. Second, in longstanding UC, an integrated approach of colorectal cancer surveillance, by using the advanced endoscopic imaging together with mucosal markers, like HSP, could result in being markedly helpful, both to clinicians and pathologist. In fact, current guidelines recommend that image-enhanced endoscopy (IEE) may increase the yield of detection of dysplasia, thus representing a reasonable alternative to the random sampling of colon using standard white light [7]. The use of both IEE and new biomarkers, like HSP, predicting future occurrence of colonic neoplasia, could lead to a more centralised approach of UC patients, in which a ‘‘biomarker-based surveillance’’ might play a pivotal rol

Dermoscopy of uncommon variants of dermatofibrosarcoma protuberans

Darier-Ferrand dermatofibrosarcoma protuberans (DFSP) is a locally aggressive fibrohistiocytic tumour with a low metastatic potential.(1) Because of its rarity, slow progression and lack of early clinical clues, the diagnosis of DFSP is often delayed. Classical DFSP clinically appeared like an indurated, irregularly-shaped plaques exhibiting flesh to reddish-brown colour. Some lesions also showed thin teleangectasia on the surface (Fig. 1, a). This article is protected by copyright. All rights reserved

EUROMEDITERRANEAN BIOMEDICAL JOURNAL: THE RENEWED MANUSCRIPT LAYOUT AND WEB RENDERING FORESHADOW FURTHER JOURNAL IMPROVEMENT

In January 2006, a new journal, Capsula Eburnea, was born into the Italian scientific publishing scene with the initial goal of creating, at the same time, \u201can open scientific forum and a blog\u201d, based on the premise that \u201cin medicine, nothing should be considered stable, immutable or unsusceptible to critical review at any time, by any scientist\u201d. The Editorial Team progressively sought to improve the quality of the manuscripts published, introducing the requirement for all articles to be written in English, and changed the Journal\u2019s name to EuroMediterranean Biomedical Journal in 2012. Over the last five years, approximately 125 articles by young doctors (including original articles, reviews, commentaries, notes, and abstract books) have been published. The editorial board are confident that the new publishing layout and the renewed web-portal of the journal, introduced in this editorial, represent an essential upgrade after over 10 years of editorial activity, and that these improvements will be appreciated by our authors and, especially, our readers

Euromediterranean Biomedical Journal: the renewed journal of young doctors aims even higher.

In January 2006, a new journal, Capsula Eburnea, was born in the Italian scientific pub-lishing scene, with the initial goal of creating, at the same time, “an open scientific forum and a blog”. Until December 2009, the vast majority of manuscripts was still published in Italian, restricting the number of readers. From the end of 2009, the journal has undergone extensive changes, becoming indexed in the main scientific search engines (Scopus, Directory of Open Access Journal, Google Scholar, Ulrich Periodical Directory), and renewing its Editorial Team with a role reassign-ment and expanding the Editorial Board to up to 40 young doctors with proven scientific experience from 15 countries around the world, working as researchers, PhD students, senior medical staff, research fellows or doctors in specialist training. Finally, the journal has progressively encouraged the publication of articles in English, through an endorsed English translation service provided by native English speaking translators. This service became mandatory for all peer-reviewed articles accepted by the Journal in 2011. At the same time, the Editorial Board unanimously decreed to change the name of the journal into “Euromediterranean Biomedical Journal for young doctors (formerly: Capsula Eburnea)” from January 2012. Today, the journal is fully open access (including the archives of Capsula Eburnea) with the possibility to download articles for free, and the publication process involves a blind peer review of each article by at least two scientists. During its first two years of activity, the Euromediterranean Biomedical Journal (EMBJ) published 48 scientific articles (17 origi-nal articles, 14 reviews, 13 case report, two technical reports and two commentaries) and one edition of Conference Proceedings