Experimental optimization of process parameters in CuNi18Zn20 micromachining

Ultraprecision micromachining is a technology suitable to fabricate miniaturized and complicated 3-dimensional microstructures and micromechanisms. High geometrical precision and elevated surface finishing are both key requirements in several manufacturing sectors. Electronics, biomedicals, optics and watchmaking industries are some of the fields where micromachining finds applications. In the last years, the integration between product functions, the miniaturization of the features and the increasing of geometrical complexity are trends which are shared by all the cited industrial sectors. These tendencies implicate higher requirements and stricter geometrical and dimensional tolerances in machining. From this perspective, the optimization of the micromachining process parameters assumes a crucial role in order to increase the efficiency and effectiveness of the process. An interesting example is offered by the high-end horology field. The optimization of micro machining is indispensable to achieve excellent surface finishing combined with high precision. The cost-saving objective can be pursued by limiting manual post-finishing and by complying the very strict quality standards directly in micromachining. A micro-machining optimization technique is presented in this a paper. The procedure was applied to manufacturing of main-plates and bridges of a wristwatch movement. Cutting speed, feed rate and depth of cut were varied in an experimental factorial plan in order to investigate their correlation with some fundamental properties of the machined features. The dimensions, the geometry and the surface finishing of holes, pins and pockets were evaluated as results of the micromachining optimization. The identified correlations allow to manufacture a wristwatch movement in conformity with the required technical characteristics and by considering the cost and time constraints

Effectiveness of a steel ring-frame for the seismic strengthening of masonry walls with new openings

The creation of new openings in masonry walls is a frequent intervention in existing buildings. Depending on their size and position, these interventions may cause a significant decrease of the wall’s original in-plane strength and stiffness, thus compromising the building seismic resistance. Therefore, in masonry buildings, strengthening techniques may be required to (i) restore as much as possible the loss of stiffness and strength, (ii) be reversible and (iii) respect the compatibility between materials, particularly in the case of historical buildings. In an attempt to comply with these requirements, engineering practitioners often introduce very stiff steel profiles forming a ring-frame inside the opening for fully restoring the stiffness and resistance without substantially increasing the building's weight. However, the effectiveness of this technique is typically quantified using linear elastic analysis and a simple sum of the flexural and shear stiffness of the masonry panels and the steel ring-frame. The present work aims to improve the knowledge and better understanding of the effectiveness of this traditional steel ring-frame technique, through experimental and numerical methods. The experimental program was designed to provide a full assessment of the effects of introducing a new door opening in brick masonry walls, from the cutting process to the application of in-plane cyclic lateral deformations. The steel ring-frame was designed using numerical tools and consisted of four profiles welded together and tied to the surrounding masonry wall by means of steel dowels dry-driven into calibrated holes of the brick. Results show that the steel ring-frame system restores the original solid wall’s in-plane strength and ductility, but not the lateral stiffness, despite the use of large steel profiles.MIUR -Ministero dell’Istruzione, dell’Università e della Ricerca(undefined

Effects of new openings on the in/plane behaviour of unreinforced brick masonry walls

Existing brick masonry buildings are frequently modified to satisfy nowadays living demands. Such modifications may include new windows or doors that connect two rooms and require openings to be cut from load bearing walls. In current design practice, these interventions are generally designed and verified for vertical load, but the structural behavior of these altered walls when submitted to in-plane loads (due to seismic actions) is not yet fully understood. Thus, design practice may be inaccurately estimated. The objective of this work is to evaluate, numerically and experimentally, the effects of introducing openings in masonry solidbrick walls subjected to in-plane loading. Three main parameters are considered for the numerical studies: i) walls dimensions, ii) opening type, iii) opening size. As expected, results show that walls with medium-large openings are the most vulnerable case-scenario. These numerical results have addressed the design of a representative wall tested at the University of Brescia. The preliminary results of this experimental program are included in this pape

Experimental and numerical assessment of masonry walls with new openings strengthened with steel frame

The creation of new openings in masonry walls is a frequent intervention executed in existing buildings of unreinforced masonry composed of clay bricks. These openings are widely seen at the street-level, where spaces are modified to create new windows or doors for new stores, garages or offices. Depending on their size and position, these interventions may cause significant decrease of the wall’s original in-plane strength and stiffness, thus, compromising the building seismic resistance. For example, when several garages are created, one after another, the risk of inducing the soft-story mechanism, when earthquake forces arrive, increases. Another example is when a door of significant size is introduced in an originally solid masonry wall, which was a key object to guarantee the box-like behavior of the structure. The opening would reduce the cross section of the remaining piers and spandrel, and thus, weaken the wall’s seismic strength. These changes in the original wall have consequences in the box-like behavior, as during earthquake events, the load demands on the remaining shear walls might be larger than their shear capacity. Therefore, strengthening techniques must restore as much as possible the loss of stiffness and strength. Besides, for masonry structures, the technique must be reversible and respect the compatibility between materials, particularly in the case of protected assets. In an attempt to complying with these requirements, engineering practitioner often introduce steel profiles forming a frame inside the opening. Steel is usually preferred because of its high level of reversibility and the stiffness and strength it can provide to masonry without substantially increasing the building self-weight. The design of this steel frame and the stiffness of the masonry wall with opening is based in the available analytical tools, i.e., the Timoshenko Beam Theory. From these calculations, the loss of stiffness when passing from a solid wall to a perforated wall is about 75% for cantilever boundary conditions and 55% for double-fixed. Thus, very stiff profiles for the steel frame are required. In theory, these profiles are capable of fully restoring the stiffness and resistance. The present work is dedicated to evaluate the effectiveness of this steel frame technique by means of experimental and numerical methods. The experimental program was designed to provide full assessment of the effects of introducing a new door opening in brick masonry walls, from the perforation process to the application of in-plane cyclic loads . A flexible steel frame was designed using numerical tools and consisted in four profiles welded together and tied to the surrounding masonry wall by means of dry-driven dowels. The numerical model was validated against the experimental results, and show that neither a very stiff steel frame nor a more flexible one is capable of restoring the original solid wall’s stiffness. However, both are capable of restoring the in-plane strength and ductility. This paper, also shows that using a very stiff profile might lead to a rather brittle response of the reinforced wall, as the masonry starts cracking before activating the frame. This would not happen with a more flexible profileItalian Ministry of Education, University, and Research (MIUR) for her Doctoral Scholarship is gratefully acknowledged. The Authors also thank the technicians A. del Barba, A. Botturi from laboratory Pietro Pis

New openings in unreinforced masonry walls under in-plane loads: a numerical and experimental study

Nowadays, existing masonry buildings are frequently modified to satisfy living demands. These modifications may require the addition of new windows or doors in walls of structural functionality. In engineering practice, such modifications are generally designed and verified for vertical loads while, for seismic loads, the changes in the walls' structural behaviour are not yet fully understood. Consequently, current design may incorrectly estimate the in-plane response of the perforated walls. This paper presents an evaluation of the effects of the introduction of new openings in masonry walls under in-plane loads by a numerical and experimental approach. Two parameters are considered for the numerical studies: opening size and eccentricity. The results show that the loss in stiffness and strength due to new openings are proportional to the opening area and that the eccentricity might change the wall response going from rocking to shear dominant behaviour, depending on the load direction

Diagnostic performance of endoscopic ultrasound-guided tissue acquisition of splenic lesions: systematic review with pooled analysis

Background: Focal splenic lesions are usually incidentally discovered on radiological assessments. Although percutaneous tissue acquisition (TA) under trans-abdominal ultrasound guidance is a well-established technique for obtaining cyto-histological diagnosis of focal splenic lesions, endoscopic ultrasound (EUS)-guided TA has been described in several studies, reporting different safety and outcomes. The aim was to assess the pooled safety, adequacy, and accuracy of EUS-TA of splenic lesions. Methods: A comprehensive review of available evidence was conducted at the end of November 2021. All studies including more than five patients and reporting about the safety, adequacy, and accuracy of EUS-TA of the spleen were included. Results: Six studies (62 patients) were identified; all studies have been conducted using fine-needle aspiration (FNA) needles. Pooled specimen adequacy and accuracy of EUS-TA for spleen characterization were 92.8% [95% confidence interval (CI), 86.3%-99.3%] and 88.2% (95% CI, 79.3%-97.1%), respectively. The pooled incidence of adverse events (six studies, 62 patients) was 4.7% (95% CI, 0.4%-9.7%). Conclusion: EUS-FNA of the spleen is a safe technique with high diagnostic adequacy and accuracy. The EUS-guided approach could be considered a valid alternative to the percutaneous approach for spleen TA

HEPATITIS C IS ASSOCIATED WITH HIGH LEVELS OF CIRCULATING N-TERMINAL PRO-BRAIN NATRIURETIC PEPTIDE AND INTERLEUKIN-6

To our knowledge, no study has evaluated N-terminal pro-brain natriuretic peptide (NTproBNP) together with interleukin-6 (IL-6) and interferon (IFN)-gamma serum levels in a large series of patients with hepatitis C virus (HCV) as possible markers of cardiac dysfunction. NTproBNP and IL-6 serum levels were valued in 55 HCV-patients, and in 55 sex- and age-matched controls. HCV-patients showed significantly higher mean NTproBNP and IL-6 levels than controls (P= 0.001); no significant difference was observed for IFN-gamma. By defining high NTproBNP level as a value higher than 300 pg/mL (that is used to rule out heart failure in patients under 75 years of age), 12% (6/49) of HCV-patients and 0 of controls had NTproBNP (chi(2); P = 0.012). In conclusion, this study demonstrates high levels of circulating NTproBNP and IL-6 in HCV-patients. The increase of NTproBNP may indicate the presence of a subclinical cardiac dysfunction. Further prospective studies quantifying symptoms and correlating these with echocardiographic parameters are needed to confirm this association

Digital droplet PCR is a specific and sensitive tool for detecting IDH2 mutations in acute myeloid leukemia patients

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) interfere with cellular metabolism contributing to oncogenesis. Mutations of IDH2 at R140 and R172 residues are observed in 20% of acute myeloid leukemias (AML), and the availability of the IDH2 inhibitor Enasidenib made IDH2 mutational screening a clinical need. The aim of this study was to set a new quantitative polymerase chain reaction (PCR) technique, the drop-off digital droplet PCR (drop-off ddPCR), as a sensitive and accurate tool for detecting IDH2 mutations. With this technique we tested 60 AML patients. Sanger sequencing identified 8/60 (13.5%) mutated cases, while ddPCR and the amplification refractory mutation system (ARMS) PCR, used as a reference technique, identified mutations in 13/60 (21.6%) cases. When the outcome of IDH2-mutated was compared to that of wild-type patients, no significant difference in terms of quality of response, overall survival, or progression-free survival was observed. Finally, we monitored IDH2 mutations during follow-up in nine cases, finding that IDH2 can be considered a valid marker of minimal residual disease (MRD) in 2/3 of our patients. In conclusion, a rapid screening of IDH2 mutations is now a clinical need well satisfied by ddPCR, but the role of IDH2 as a marker for MRD still remains a matter of debate