Mechanical and tribo-metallurgical behavior of 17-4 precipitation hardening stainless steel affected by severe cold plastic deformation: a comprehensive review article

This article comprehensively reviews the mechanical properties and tribo-metallurgical behavior of 17-4 precipitation hardening stainless steel (17-4PH SS) during and after cold plastic deformation. Referring to the scientific literature, stainless steels are one of the few types of ferrous alloys which could be appropriately set up through cold working processes in the forms of sheets or other shapes. Likewise, some other metal alloys such as mild low-carbon-based steels, copper and its alloys, aluminum alloys, and some others are the few types of metal alloys which have this capability. On the other hand, in engineering applications, there are several types of mechanical failures, which must be taken into account to investigate the mechanical behavior and tribo-metallurgical properties of any targeted materials. For example, corrosion resistance, wear resistance, and fatigue failure are investigated according to the microstructural studies, comprising of the grain size, grain boundaries, orientations, dislocations, and so on. Based on the published results, focusing on 17-4PH SS, one of the most main effective factors on mechanical and tribo-metallurgical performance is the grain size. Also, the favorable balance of two mechanical properties of strength and ductility has been reported as a dilemma in the materials science, and the problem delineates upon the limitations of numerous structural materials potentials. Following the failure analysis of the materials, in order to diminish the damages caused by fretting fatigue some methods such as ultrasonic processes are applied for the treatment of 17-4PH SS via changing the microstructure, residual stress, and other parameters. Also, through the other cold deformation technologies, the nanostructured surface layer with highly upgraded mechanical properties of several ultrasonic surface rolling process-treated 17-4PH SS has been obtained. To this end, such cold working processes on 17-4PH SS and their subsequent results are elaborated in this review paper. Graphical abstract: [Figure not available: see fulltext.

Protein folding and quinary interactions: creating cellular organisation through functional disorder

The marginal stability of globular proteins in the cell is determined by the balance between excluded volume effect and soft interactions. Quinary interactions are a type of soft interactions involved in intracellular organisation and known to have stabilising or destabilising effects on globular proteins. Recent studies suggest that globular proteins have structural flexibility, exhibiting more than one functional state. Here, we propose that the quinary-induced destabilisation can be sufficient to produce functional partially unfolded states of globular proteins. The biological relevance of this mechanism is explored, involving intracellular phase separation and regulatory stress response mechanisms.The authors thank Hernani Geros for useful comments on the manuscript and Michael Smith for language advices. In addition, JCM and SR acknowledge the Foundation for Science and Technology, FCT- Portugal, for financial support through the Centre of Chemistry of the University of Minho (CQ-UM) (projects UID/QUI/00686/2013 and UID/QUI/00686/2016). SE acknowledges funding from the Cluster of Excellence RESOLV (EXC 1069) funded by the German Research Foundation (DFG) and the Human Frontier Science Program Organization Research Grant (Project: RGP0022/2017)

Systemic treatment for hepatocellular carcinoma beyond milan criteria on the waitlist: is it time for a neoadjuvant therapy?

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Effect of Shot Peening on Oxidation and Precipitation in Inconel 718

In this study, the effect of the surface state on the behaviour of Inconel 718 alloy exposed to 640 ∘ C and 700 ∘ C environments for times varying between one and one hundred hours was investigated. In particular, the focus was set on the evolution of oxidation and precipitation phenomena during thermal exposure. Three surface states were considered: two generated through shot peening treatments featuring different coverage levels, while the third condition is a non-peened one. Shot peening treatments modify the surface condition and introduce higher residual stresses and microhardness values than in the non-treated condition. The morphology of the oxides appears to be different depending on the condition observed. Regarding the kinetics, over time the oxidation process follows a parabolic trend and appears to be influenced by the surface state; in particular, severe shot peening treatment is characterized by the highest intensity of the phenomenon. However, the order of magnitude of the weight gains measured suggests that the observed variations can be neglected, and that the positive effect of shot peening can be exploited without introducing oxidation problems. From the point of view of the microstructural evolution, an increase in the coarsening kinetics of γ ” phase was observed in the shot peened layer

Characterization and Comparison of Single VAR-Remelted and Double VAR-Remelted Ingots of INCOLOY ® Alloy 925

Alloy 925 is a nickel-based superalloy usually produced by Electric Arc Furnace (EAF), followed by Argon Oxygen Decarburization (AOD) and Vacuum Arc Remelting (VAR). It can undergo to one VAR remelting (EAF-AOD-VAR) or, if necessary due to process instabilities, two VAR remelting (EAF-AOD-VAR-VAR). The characterization of A925 ingots remelted one or two times after forging and aging was carried out to enhance differences. The VAR remelting rate of single- or double-remelted samples was correlated to metallurgical and mechanical properties. The microstructure observation revealed a higher quantity of MC, M23C6 and TiN precipitates (both inter- and intragranular) in single-remelted samples: the intergranular ones increase in quantity going from the ingot center position to the external one where cluster of titanium nitrides were detected. The higher presence of intergranular precipitates causes a high deterioration of impact toughness (71.1 ± 12.7 vs 90.5 ± 7.1 J) and lateral expansion (0.91 ± 0.18 vs 1.14 ± 0.07 mm). On the other hand, the number of remelting does not affect other tensile properties and hardness. Therefore, the different behavior of forged ingots at single and double remelting are not related to the number of remelting and remelting rate. On the other hand, the slightly lower toughness of single-remelted forged ingots can be corelated to defects derived from casting

New Mussel Inspired Polydopamine-Like Silica-Based Material for Dye Adsorption

A straightforward and economic procedure has been developed for the synthesis of a new polydopamine-like silica-based material that has been obtained by oxidation of catechol with KIO4 followed by reaction with 3-aminopropyltrimethoxysilane. All techniques adopted for characterization showed that the obtained material is rich in different functional groups and the morphological analyses revealed dimensions in the nanometric range. The hybrid material has been characterized by several techniques showing its polydopamine-like nature, and preliminary observations for dye adsorption have been reported.University of Palermo PRIN2017- 2017YJMPZ

Efficacy and safety of basiliximab with a tacrolimus-based regimen in liver transplant recipients

Background. Induction with monoclonal antibodies for prevention of acute cellular rejection (ACR) may avoid many of the adverse events associated with polyclonal antibodies. Basiliximab, a chimeric monoclonal antibody directed against the α-chain of the interleukin 2 receptor (CD25), has been extensively evaluated as an induction therapy for kidney transplant recipients, more frequently in combination with a cyclosporine-based regimen. In this study, we assessed the efficacy and safety of basiliximab in combination with a tacrolimus-based regimen after liver transplantation. Methods. Fifty consecutive liver transplants (47 cadaveric donors; 3 living donors) were analyzed. All patients received two 20-mg doses of basiliximab (days 0 and 4 after transplantation) followed by tacrolimus (0.15 mg/kg/day; 10-15 ng/mL target trough levels) and a tapered dose regimen of steroids. Follow-up ranged from 404 to 1,364 days after transplantation (mean 799.89 days, SD±257.37; median 796 days). Results. A total of 88% of patients remained rejection-free during follow-up with an actuarial rejection-free probability of 75% within 3 months. The actuarial patient survival rate at 3 years was 88%, and the graft survival rate was 75%. Twelve (24%) patients experienced one episode of sepsis, requiring temporary reduction of immunosuppressive therapy. There were no immediate side effects associated with basiliximab and no evidence of cytomegalovirus infection or posttransplant lymphoproliferative disorder. Conclusions. Basiliximab in combination with a tacrolimus-based immunosuppressive regimen is effective in reducing episodes of ACR and increasing ACR-free survival after liver transplantation. In addition, basiliximab does not increase the incidence of adverse effects or infections

Left Spigelian Hernia in Super-Obese Patient: A Case-Report.

Abstract: We report a case in which a giant Spigelian hernia presented with severe, persistent abdominal pain in a 62- year-old super-obese woman with a history of total abdominal hysterectomy-bilateral salpingo-oopherectomy at the age of 40 years for benign neoplasia, who later underwent open hernia repair (maximal diameter of the hernia sac: 21 cm) because of the development of compartment syndrome. Afterward, although a large incarcerated hernia disease was found, the sac removal was technically difficult and an open procedure was carried out, with double-mesh placement. No complications were recorded during the post-operative course. We report a difficult issue related to the diagnosis and management of this pathology, underlining the complete surgical repair to avoid hernia recurrence

Hepatic incidentaloma: An asymptomatic ectopic thyroid tissue

: An ectopic thyroid is a form of thyroid dysgenesis in which the entire thyroid gland or parts of it may be located in another part of the body than the usual place. The most frequent location is the base of the tongue. Although most cases are asymptomatic, symptoms related to tumor size and its relationship with surrounding tissues, hormonal dysfunction, and seldom malignancy may also occur. Here, we describe the case of an asymptomatic woman who was thyroidectomized 19 years previously for a toxic goiter and treated with conventional L-thyroxine therapy, until we enacted a progressive reduction of dosage of the replacement therapy. Incidentally, because of occasional abdomen discomfort, she was hospitalized in our Division of Endocrinology as there was ultrasound evidence of a large mass in the liver dislocating and imprinting the choledochal duct in the pre-pancreatic site, the gallbladder, and the cystic duct, which could not be dissociated from the contiguous hepatic parenchyma and was in very close proximity to the second duodenal portion and the head of the pancreas. Imaging techniques, such as TC, MR, TC/PET, and 131I scintigraphy, confirmed the large lesion with a diameter on the axial plane of about 8 × 5.5 cm and a cranio-caudal extension of about 6 cm. The impossibility of surgical debulking and/or radiometabolic 131I therapy, in the absence of compression symptoms, led to the multidisciplinary decision of a clinical and instrumental follow-up of this rare lesion