on the surface integrity of electron beam melted ti6al4v after machining

Abstract The Additive Manufacturing process known as Electron Beam Melting (EBM) is increasingly used to produce Ti6Al4V biomedical parts, whose functional surfaces, however, need to be machined afterwards. The paper addresses the fundamental issue of surface integrity of EBM parts when subjected to machining operation under dry, flood and cryogenic cooling conditions. The machined surface integrity is evaluated in terms of microstructural and mechanical features, residual stresses, surface topography and defects. Results are then compared to the outcomes of the same machining tests carried out on the conventional wrought alloy. This study points out the different machinability of the two investigated alloys, highlighting that new insights into optimization of parameters for machining AM alloys are needed

Clinical presentation and management of acromegaly in elderly patients

Background and aim: Acromegaly is a rare disease with a peak of incidence in early adulthood. However, enhanced awareness of this disease, combined with wide availability of magnetic resonance imaging (MRI), has increased the diagnosis of forms with mild presentation, especially in elderly patients. Moreover, due to increased life expectancy and proactive individualized treatment, patients with early-onset acromegaly are today aging. The aim of our study was to describe our cohort of elderly patients with acromegaly. Materials and methods: This is a cross-sectional retrospective study of 96 outpatients. Clinical, endocrine, treatment, and follow-up data were collected using the electronic database of the University Hospital of Padova, Italy. Results: We diagnosed acromegaly in 13 patients, aged 6565\ua0years, presenting with relatively small adenomas and low IGF-1 secretion. Among them, 11 patients were initially treated with medical therapy and half normalized hormonal levels after 6\ua0months without undergoing neurosurgery (TNS). Remission was achieved after TNS in three out of four patients (primary TNS in two); ten patients presented controlled acromegaly at the last visit. Acromegaly-related comorbidities (colon polyps, thyroid cancer, adrenal incidentaloma, hypertension, and bone disease) were more prevalent in patients who had an early diagnosis (31 patients, characterized by a longer follow-up of 24\ua0years) than in those diagnosed aged 6565\ua0years (5\ua0years of follow-up). Conclusions: Elderly acromegalic patients are not uncommon. Primary medical therapy is a reasonable option and is effectively used, while the rate of surgical success is not reduced. A careful cost-benefit balance is suggested. Disease-specific comorbidities are more prevalent in acromegalic patients with a longer follow-up rather than in those diagnosed aged 6565\ua0years

Laboratory injection molder for the fabrication of polymeric porous poly-epsilon-caprolactone scaffolds for preliminary mesenchymal stem cells tissue engineering applications

This study presents a simple and rapid fabrication technique involving injection molding and particle leaching (IM/PL) to fabricate the porous scaffold for tissue engineering applications. Sodium Chloride (NaCl) and Sucrose are separately mixed with the poly-epsilon-caprolactone (PCL) granules using a screwed thermo-regulated extruder, then the biocompatible scaffolds are fabricated through injection molding. The micro/nano-structure of the samples and their different grade of porosity were characterized by scanning electron microscopy and mercury intrusion porosimetry. Bone marrow-derived mesenchymal stem cells are chosen for cell culture and Hoechst 33342 staining was used to verify the biocompatibility of the polymeric porous surfaces. We concluded that, by using the same fast solvent free injection/leaching process, the use of Sucrose as porogen, instead of NaCl, allowed the obtainment of biocompatible scaffolds with a higher grade of porosity with suitable cell adhesion capacity for tissue engineering purpose

Infliximab: 12 years of experience

Rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) are immune-mediated conditions that share an inflammatory mechanism fuelled by excessive cytokines, particularly TNF. Control of inflammation and rapid suppression of cytokines are important in treating these diseases. With this understanding and the corresponding advent of TNF inhibitors, RA patients, AS patients and PsA patients have found more choices than ever before and have greater hope of sustained relief. As a widely used TNF inhibitor, infliximab has a deep and established record of efficacy and safety data. Extensive evidence - from randomised controlled clinical trials, large registries and postmarketing surveillance studies - shows that infliximab effectively treats the signs and symptoms, provides rapid and prolonged suppression of inflammation, prevents radiologically observable disease progression and offers an acceptable safety profile in RA, AS and PsA. In very recent studies, investigators have observed drug-free remission in some patients. Additionally, infliximab may interfere with rapidly progressing disease in RA by early addition to methotrexate in patients with signs of an aggressive course. Finally, infliximab has been shown to reduce PsA clinical manifestations such as nail involvement. With our current understanding, substantial data and increasing confidence regarding use in practice, infliximab can be considered a well-known drug in our continued campaign against inflammatory rheumatic diseases

Pituitary-adrenal axis and peripheral cortisol metabolism in obese patients

Background and aim: A close relationship between adiposity and increased cortisol levels is well established in patients with endogenous hypercortisolism. Nevertheless, hypothalamic-pituitary-adrenal (HPA) axis regulation in overweight subjects is still a matter of concern. We studied free cortisol (urinary free cortisol, UFC and late night salivary cortisol, LNSC), pituitary feedback (serum cortisol after 1 mg dexamethasone suppression test, 1 mg DST) and peripheral cortisol metabolism (urinary cortisol to cortisone ratio, F/Eratio) in a large series of overweight subjects without Cushing\u2019s Syndrome. Materials and methods: We considered 234 patients divided in 5 BMI classes, matched for age and gender (BMI 64 25 kg/m2n = 38; 25\u201330 n = 58; 30\u201335 n = 52; 35\u201340 n = 52; >40 n = 34). UFC, LNSC and urinary F/Eratio were assessed with LC-MS. Results: We collected 183 LNSC, 176 UFC, 152 1 mg DST and 64 F/Eratio tests. UFC levels were higher in lean subjects, and they decreased according to the BMI classes (p = 0.022). Non-suppressed cortisol levels (>50 nmol/L) after 1 mg DST were observed especially in patients with normal weight or mild obesity. Patients with BMI 65 35 kg/m2 revealed a reduced F/Eratio (0.39 vs. 0.61, p = 0.006). The specificity of tests (false positive results) was higher considering 1 mg DST or UFC in obese patients, on the contrary impaired cortisol rhythm (LNSC above normality) was observed in 47 subjects, irrespective of weight. Conclusions: Overweight and obese subjects are characterised by an original regulation of HPA axis (reduced UFC levels, increased suppression after 1 mg DST) and peripheral cortisol metabolism (reduced F/Eratio), suggesting an effort to counteract hypercortisolism

Improving surface integrity and corrosion resistance of additive manufactured Ti6Al4V alloy by cryogenic machining

Additive manufacturing (AM) processes are rapidly growing, thanks to the chance they offer for the component customization in terms of both in-service performances and geometrical features. Nevertheless, AM products still need finishing operations to obtain suitable surface finish, which may introduce machinability issues on the basis of the different mechanical and microstructural characteristics AM metal alloys have compared with the wrought ones. This work presents the pivotal topic of surface integrity evaluation of electron beam melted (EBM) Ti6Al4V titanium alloy after finishing turning operations carried out under dry, flood, and cryogenic cooling conditions at different feed rates. For the sake of comparison, the same machining trials were conducted on the wrought alloy. The machining-induced effects were broadly studied in terms of microstructural and mechanical features, residual stress nature, surface topography, and defects. Moreover, the corrosion behavior of the machined surfaces in simulated physiological conditions was also tested, proving that the combination of the particular microstructure of the EBM Ti6Al4V alloy with cryogenic machining allowed for significant improvement of the corrosion performances

Anisotropy effect of additively manufactured Ti6Al4V titanium alloy on surface quality after milling

The microstructural and mechanical anisotropy of metallic additive manufactured parts is well-established as the nature itself of the process induces the formation of columnar grains along the build-up direction. However, the effect of this anisotropy on the alloy machinability is rarely considered and a deeper understanding is needed. In the current study, Ti6Al4V prisms were fabricated by laser powder bed fusion in both vertical and horizontal orientation. After heat treatment, the prisms were slot milled at different cutting parameters to assess the influence of the build-up orientation on the surface quality, focusing on the surface topography. The results show that the skewness parameter can distinguish the machined surface of differently oriented AM parts and that the horizontal orientation allows for better machinability when considering the burrs height and the chip morphology

Influence of additive manufacturing-induced anisotropy on tool wear in end milling of Ti6Al4V

Additive manufacturing induces a microstructural anisotropy in its components, that reflects on their mechanical properties, and, in turn, on their machinability. In this paper, the tool wear when milling laser powder bed fused Ti6Al4V parts with four different build-up orientations was evaluated. The tool wear was qualitatively and quantitatively examined, and assessed indirectly by analyzing the chip morphology and the machined surface quality. This study demonstrates that the tool life decreases gradually up to 40%, going from machining horizontally manufactured samples to vertically manufactured ones. Furthermore, a novel interpretation of the correlation between the tool life and the additive manufacturing-induced anisotropy of the part was given

Long-course temozolomide in aggressive pituitary adenoma: real-life experience in two tertiary care centers and review of the literature

Purpose: Aggressive pituitary adenomas (APAs) and pituitary\ua0carcinomas (PCs) are challenging for their invasive nature, resistance to treatment and recurrences. Temozolomide (TMZ) is used with benefit and well-tolerated toxicity profile in APAs and PCs. In most studies patients received 64 12 cycles but the best length of treatment is debated since other options after discontinuation are scarce and a second course is mainly unsuccessful. Methods: We report outcomes of 8 patients with APAs and PCs treated with TMZ for more than 12 continuous cycles with a literature review. Data were retrospectively collected from Padua and Milan University Hospitals. TMZ was used as a single agent (150\u2013200 p.o. mg/m2 daily, 5/28\ua0days) for 14 to 45 cycles. Results: Eight patients (7\ua0M), 7 APAs and 1 PC. Previous treatments included neurosurgery and radiotherapy in all cases except two giant masses (ACTH-silent APA and prolactinoma). No patient had progression disease (PD) during long-term treatment nor toxicities. No one had complete response (CR) but four had partial response (PR). Four ACTH+ tumors maintained stable disease (SD) but the secretion pattern improved in all. After drug withdrawal, three had delayed PD (2 after 18 and one after 29\ua0months, all ACTH+); two are still in SD. Conclusions: TMZ may be useful and well-tolerated in APAs and PCs as a long-term therapy. PR appears within the first cycles with no escape throughout the treatment; most patients achieve SD. We suggest extended protocols particularly in responsive ACTH+ PAs and PCs, when further therapies may be unsuccessful