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.

Thermodynamics of a mixed quantum-classical Heisenberg model in two dimensions

We study the planar antiferromagnetic Heisenberg model on a decorated hexagonal lattice, involving both classical spins (occupying the vertices) and quantum spins (occupying the middle of the links). This study is motivated by the description of a recently synthesized molecular magnetic compound. First, we trace out the spin 1/2 degrees of freedom to obtain a fully classical model with an effective ferromagnetic interaction. Then, using high temperature expansions and Monte Carlo simulations, we analyse its thermal and magnetic properties. We show that it provides a good quantitative description of the magnetic susceptibility of the molecular magnet in its paramagnetic phase.Comment: Revtex, 6 pages, 4 included postscript figures, fig.1 upon request to [email protected] . To appear in J. of Physic C (condensed matter

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

Individual dosage of digoxin in patients with heart failure

Backgroud: After the publication of DIG trial, the therapeutic target of serum digoxin concentration (SDC) for the treatment of heart failure (HF) has been lowered (0.40-1.00 ng/ml). However, the majority of equations to calculate digoxin dosages were developed for higher SDCs. Recently, a new equation was validated in Asian population for low SDCs by Konishi et al., but results in Caucasians are unknown. Aim: This study was aimed to test the Konishi equation in Caucasians specifically targeting low SDCs. Furthermore, the Konishi equation was compared with other frequently used equations. Design: This was a prospective, multicenter study. Methods: Clinically indicated digoxin was given in 40 HF patients. The dosage was calculated with the Konishi equation. The SDC was measured at 1 and 6 months after starting digoxin. Adherence to digoxin was monitored with a specific questionnaire. Results: After exclusion of patients admitting poor adherence, we found a reasonable correlation between predicted and measured SDC (r = 0.48; P < 0.01) by the Konishi equation. Excluding patients with poor adherence and relevant worsening of renal function, the measured SDC (n = 54 measurements) was within the pre-defined therapeutic range in 95% of the cases. The mean, maximal and minimal measured SDC were 0.69 ± 0.19, 1.00 and 0.32 ng/ml, respectively. The correlation was weaker for the Jelliffe, the Koup and Jusko, and the Bauman equations. Conclusions: This study supports the clinical validity of the Konishi equation for calculating individual digoxin dosage in Caucasians, targeting SDCs according to current HF guideline

Animal production in different integrated crop-livestock systems in a lowland of Southern Brazil.

To achieve higher lowland use efficiency in Brazilian Southern, a region commonly used for rice production, the livestock activity during the winter period (in succession to summer crops) is a sustainable alternative..

Neuropsychological changes in isolated REM sleep behavior disorder: A systematic review and meta-analysis of cross-sectional and longitudinal studies

The aim of this meta-analysis is twofold: (a) to assess cognitive impairments in isolated rapid eye movement (REM) sleep behavior disorder (iRBD) patients compared to healthy controls (HC); (b) to quantitatively estimate the risk of developing a neurodegenerative disease in iRBD patients according to baseline cognitive assessment. To address the first aim, cross-sectional studies including polysomnography-confirmed iRBD patients, HC, and reporting neuropsychological testing were included. To address the second aim, longitudinal studies including polysomnography-confirmed iRBD patients, reporting baseline neuropsychological testing for converted and still isolated patients separately were included. The literature search was conducted based on PRISMA guidelines and the protocol was registered at PROSPERO (CRD42021253427). Cross-sectional and longitudinal studies were searched from PubMed, Web of Science, Scopus, and Embase databases. Publication bias and statistical heterogeneity were assessed respectively by funnel plot asymmetry and using I2. Finally, a random-effect model was performed to pool the included studies. 75 cross-sectional (2,398 HC and 2,460 iRBD patients) and 11 longitudinal (495 iRBD patients) studies were selected. Cross-sectional studies showed that iRBD patients performed significantly worse in cognitive screening scores (random-effects (RE) model = –0.69), memory (RE model = –0.64), and executive function (RE model = –0.50) domains compared to HC. The survival analyses conducted for longitudinal studies revealed that lower executive function and language performance, as well as the presence of mild cognitive impairment (MCI), at baseline were associated with an increased risk of conversion at follow-up. Our study underlines the importance of a comprehensive neuropsychological assessment in the context of iRBD

Assessing Sleep Habits in Italian Community-Dwelling Adolescents: Psychometric Properties of the School Sleep Habits Survey Scales

Background. In the field of adolescent sleep research, different sleep surveys have been implemented; however, psychometric properties of these instruments have been investigated only minimally. Methods. In order to assess the psychometric properties of the Sleep-Wake Problems Behaviour Scale (SWP), the Sleepiness Scale (SLS), and the Morningness/Eveningness Questionnaire (ME), a moderately large sample of community-dwelling Italian adolescents (N = 778; 59.8% female; mean age = 15.77 years) was administered the Italian translation of the School Sleep Habits Survey. Results. Internal consistency estimates values were satisfactory for all measures; dimensionality analyses suggested a unidimensional structure for SWP, SLS and ME, respectively. Goodness-of-fit statistics for the one-factor model of the SLS, SWP, and ME scale items were adequate for all measures. Non -redundant taxometric analysis results consistently suggested a dimensional latent structure for the SLS, SWP, and ME, respectively. Conclusion. Our findings supported the use of the SLS, SWP, and ME total scores as measures of sleepiness, sleep-wake problem, and morningness/eveningness, at least among Italian community -dwelling adolescents, and encourage practitioners to rely on the conventional percentiles in order to interpret the SLS, SWP, and ME total scores

Antioxidant and enzyme inhibitory properties of the polyphenolic-rich extract from an ancient apple variety of central Italy (Mela Rosa dei Monti Sibillini)

This study was undertaken to evaluate the nutraceutical potential of the Mela Rosa dei Monti Sibillini (MR), an ancient apple variety of the Sibillini Mountains, central Italy. The chemical profile of the apple''s polyphenolic-rich extract (MRE) obtained from first-and second-choice samples using the Amberlite® XAD7HP resin was analyzed by High Performance Liquid Chromatography with Diode-Array and Mass spectrometry (HPLC-DAD-MS) and 21 phytochemicals were quali–quantitatively determined. For comparative purposes, the polyphenol-rich extract of Annurca (ANE), a southern Italian variety, was analyzed. The antioxidant capacity of MREs was evaluated by Folin–Ciocalteu, 1, 1-diphenyl-2-picrylhydrazyl (DPPH), and 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The inhibitory capacity of MREs for the enzymes a-glucosidase, lipase, monoamine oxidase A, tyrosinase, and acetylcholinesterase was also determined. The MREs showed higher polyphenolic and triterpene profiles than the ANE. Their radical scavenging activity was higher than that of ANE and comparable to the reference trolox. The MRE from the second-choice apples displayed higher contents of the 21 phytochemicals investigated. Either MRE from second-choice or first-choice samples showed enzymatic inhibition with IC50 values higher than those of reference inhibitors but worthy of nutraceutical consideration. Taken together, these results show the potential of MRE as a source of bioactive compounds to be used for pharmaceutical, nutraceutical, and cosmeceutical applications has been confirmed

Phytochemical profile and biological activities of crude and purified Leonurus cardiaca extracts

Leonurus cardiaca L. (Lamiaceae) is a perennial herb distributed in Asia and Southeastern Europe and has been used in traditional medicine since antiquity for its role against cardiac and gynecological disorders. The polar extracts obtained from L. cardiaca aerial parts contain several compounds among which alkaloids, iridoids, labdane diterpenes, and phenylethanoid glycosides play a major role in conferring protection against the aforementioned diseases. On the other hand, the antioxidant activities and the enzyme inhibitory properties of these extracts have not yet been deeply studied. On the above, in the present study, crude and purified extracts were prepared from the aerial parts of L. cardiaca and have been chemically characterized by spectrophotometric assays and HPLC-DAD-MS analyses. Notably, the content of twelve secondary metabolites, namely phenolic acids (chlorogenic, caffeic, caffeoylmalic and trans-ferulic acids), flavonoids (rutin and quercetin), phenylethanoid glycosides (verbascoside and lavandulifolioside), guanidine pseudoalkaloids (leonurine), iridoids (harpagide), diterpenes (forskolin), and triterpenes (ursolic acid), has been determined. Furthermore, the extracts were tested for their antioxidant capabilities (phosphomolybdenum, DPPH, ABTS, FRAP, CUPRAC, and ferrous chelating assays) and enzyme inhibitory properties against cholinesterase, tyrosinase, amylase, and glucosidase. The purified extracts contained higher phytochemical content than the crude ones, with caffeoylmalic acid and verbascoside as the most abundant compounds. A linear correlation between total phenolics, radical scavenging activity, and reducing power of extracts has been found. Notably, quercetin, caffeic acid, lavandulifolioside, verbascoside, chlorogenic acid, rutin, and ursolic acid influenced the main variations in the bioactivities found in L. cardiaca extracts. Our findings provide further insights into the chemico-biological traits of L. cardiaca and a scientific basis for the development of nutraceuticals and food supplements

Experimental trials and theoretical background about foaming, slag refractory interaction and feasibility of crude magnesium carbonate injection as foaming agent and its use for EAF refractory protection

A theoretical overview about the slag structure, their compatibility with the refractories and their foaming behaviorhas been realized. Such a theoretical background is the basis for the performed experimental trials focused onthe use of crude MgCO3 injected within the slag. This raw material can develop the gaseous phases (CO2) neededfor the slag foaming and it can provide the MgO useful to make the slag compatible with the refractories. Theexperimentation has been performed through the injection of different specific quantities of MgCO3 and theobtained results pointed out a significant decrease of refractory wear, a saving of the specific electric energy, adecrease of the lime injection and of the anthracite powder needed to induce the foaming effect