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This article investigates the deformation mechanics of cast iron and its implications for notch analysis, particularly in the automotive industry. Cast iron’s extensive use stems from its cost-effectiveness, durability, and adaptability to various mechanical demands. Gray, nodular, and compacted graphite cast irons are the primary types, each offering unique advantages in different applications. The presence of graphite, microcracks, and internal porosity significantly influences cast iron’s stress–strain behavior. Gray and compacted cast iron display an asymmetrical curve, emphasizing low tensile strength and superior compression performance due to graphite flakes and crack closures. Nodular cast iron exhibits a symmetrical curve, indicating balanced mechanical properties under tension and compression. The proposed simplified macrostructural approach, based on monotonic stress–strain, aims to efficiently capture graphite and crack closure effects, enhancing compressive strength and stiffness. By employing the Neuber and Molski–Glinka methods for notch analysis, we assume nominally elastic behavior of notched components. This represents a novel application for gray and compacted cast iron, aiding in predicting material fatigue life, as demonstrated in other materials with asymmetrical behavior.

Objectives To investigate the diagnostic value of cardiac magnetic resonance (CMR) feature-tracking (FT) myocardial strain analysis in patients with suspected acute myocarditis and its association with myocardial oedema. Methods Forty-eight patients with suspected acute myocarditis and 35 control subjects underwent CMR. FT CMR analysis of systolic longitudinal (LS), circumferential (CS) and radial strain (RS) was performed. Additionally, the protocol allowed for the assessment of T1 and T2 relaxation times. Results When compared with healthy controls, myocarditis patients demonstrated reduced LS, CS and RS values (LS: -19.5 ± 4.4% vs. -23.6 ± 3.1%, CS: -23.0 ± 5.8% vs. -27.4 ± 3.4%, RS: 28.9 ± 8.5% vs. 32.4 ± 7.4%; P < 0.05, respectively). LS (T1: r = 0.462, P < 0.001; T2: r = 0.436, P < 0.001) and CS (T1: r = 0.429, P < 0.001; T2: r = 0.467, P < 0.001) showed the strongest correlations with T1 and T2 relaxations times. Area under the curve of LS (0.79) was higher compared with those of CS (0.75; P = 0.478) and RS (0.62; P = 0.008). Conclusions FT CMR myocardial strain analysis might serve as a new tool for assessment of myocardial dysfunction in the diagnostic work-up of patients suspected of having acute myocarditis. Especially, LS and CS show a sufficient diagnostic performance and were most closely correlated with CMR parameters of myocardial oedema. Key Points • Myocardial strain measures are considerably reduced in patients with suspected myocarditis. • Myocardial strain measures can sufficiently discriminate between diseased and healthy patients. • Myocardial strain measures show basic associations with the extent of myocardial oedema/inflammation.

The reactivity of Zn2+ tetrahedral complexes with H2O2 was investigated in silico, as a first step in their disruption process. The substrates were chosen to represent the cores of three different zinc finger protein motifs, i. e., a Zn2+ ion coordinated to four cysteines (CCCC), to three cysteines and one histidine (CCCH), and to two cysteines and two histidines (CCHH). The cysteine and histidine ligands were further simplified to methyl thiolate and imidazole, respectively. H2O2 was chosen as an oxidizing agent due to its biological role as a metabolic product and species involved in signaling processes. The mechanism of oxidation of a coordinated cysteinate to sulfenate‐κS and the trends for the different substrates were rationalized through activation strain analysis and energy decomposition analysis in the framework of scalar relativistic Density Functional Theory (DFT) calculations at ZORA‐M06/TZ2P ae // ZORA‐BLYP‐D3(BJ)/TZ2P. CCCC is oxidized most easily, an outcome explained considering both electrostatic and orbital interactions. The isomerization to sulfenate‐κO was attempted to assess whether this step may affect the ligand dissociation; however, it was found to introduce a kinetic barrier without improving the energetics of the dissociation. Lastly, ligand exchange with free thiolates and selenolates was investigated as a trigger for ligand dissociation, possibly leading to metal ejection; molecular docking simulations also support this hypothesis. Zinc fingers are small protein domains characterized by a Zn2+ ion coordinated to four cysteines (CCCC, green), three cysteines and one histidine (CCCH, red) or two cysteines and two histidines (CCHH, blue). In oxidizing environments, the sulfur ligand can be oxidized to sulfenate by H2O2: CCCC is the easiest to oxidize, while CCHH has the highest activation energy. Thus, the oxidation resistance increases with the number of cysteines.

Throughout the plastic deformation of sheet metal axisymmetric shape parts such as hemispherical products using the spinning process, the sheet metal experiences intensive stresses and strains. Therefore, producing sheet metal pieces using this technique requires substantial skills. The study and analysis of stresses, strains, and other parameters affecting the process by means of numerical strategies or experimental setups help to better understand the stress–strain state and how the material is deformed during the process. In this study, a 3D finite element model is developed using Abaqus/Explicit solver to systematically analyze the spinning of hemispherical sheet metal parts in both single and multi-pass spinning operations and were compared with the results obtained from the experiments to confirm their validity. During the process, stresses, strains, and wall thickness distribution of the samples were investigated and compared with relevant experimental outputs. Also, the geometrical condition of the final product and applied forces to the workpiece were examined. The results obtained from the two operations (single-pass and multi-pass) indicate adequate consistency between the results of the simulation models and the experiments.

Transesophageal echocardiography (TEE) is the gold standard for assessing left atrial appendage (LAA) mechanic and thrombosis (LAAT); however, TEE is a high-risk procedure for viral transmission during coronavirus disease 2019 (COVID-19) pandemic. We investigated whether deformation indices of left atrium (LA) at transthoracic echocardiography (TTE) correlate with those of LAA assessed by TEE in nonvalvular atrial fibrillation (NVAF) patients undergoing electrical cardioversion (ECV). Consecutive patients with NVAF of ≥ 48 h or unknown duration, who underwent TEE and TTE at our Institution before ECV were retrospectively investigated. Standard echo-Doppler and LA and LAA myocardial strain and strain rate parameters were analyzed. A total of 115 NVAF patients (71.3 ± 8.1 yr/o, 59.1% men) were included: LAAT was diagnosed in 25 (21.7%) patients. Compared to patients without LAAT, those with LAAT had significantly higher CHA2DS2-VASc Risk score (4.5 ± 1.4 vs. 3.5 ± 1.1, p < 0.001), and lower ejection fraction (46.0 ± 14.8 vs. 57.6 ± 8.6%, p < 0.001). In LAAT patients, global strain of LA (8.7 ± 2.6 vs. 16.3 ± 4.5%, p < 0.001) and LAA (7.0 ± 1.7 vs. 11.7 ± 2.0%, p < 0.001) was significantly reduced compared to non-LAAT patients. A close relationship between left atrial strain reservoir (LASr) and LAA-global strain was demonstrated (r = 0.81). By univariable analysis, CHA2DS2-VASc Risk Score (OR 2.01, 95%CI 1.34–3.00), NT-proBNP (OR 1.36, 95%CI 1.19–1.54), ejection fraction (OR 0.92, 95%CI 0.88–0.96), E/e’ ratio (OR 2.07, 95%CI 1.51–2.85), and LASr (OR 0.39, 95%CI 0.25–0.62) were strongly associated with LAAT presence at TEE. By multivariable analysis, only LASr (OR 0.40, 95%CI 0.24–0.70) retained statistical significance. ROC curve analysis revealed that an LASr cut-off value ≤ 9.3% had 98.9% sensibility and 100% specificity to identify LAAT by TEE (AUC = 0.98). In patients with NVAF of ≥ 48 h or unknown duration, scheduled to undergo ECV, LA deformation assessment by TTE might substitute invasive measurement of LAA function by TEE, simplifying diagnostic approach and possibly contributing to reduce COVID-19 infection diffusion.

We have evaluated the stress–strain behavior of calcite precipitated and mechanically twinned in small-offset strike-slip, normal and thrust faults of a variety of ages and from a variety of tectonic settings (n = 3001 twin measurements, 63 strain analyses from 18 field sites). Five strike-slip faults with syn-faulting, horizontally striated calcite (rake = 0°) were studied and we report the orientations of the contemporaneous stress–strain field associated with each fault: intrusion of the Marathon Large Igneous Province mafic dikes (~ 2.1 Ga in Archean crust, Minnesota, USA); post-Keweenaw rift (1.1 Ga) faulting (Island Lake fault, central Ontario, Canada); subduction associated with metamorphic core complex formation (Cretaceous, China); subduction (Cretaceous to Miocene, Italy), and continental extension (recently active Furnace Creek fault, Death Valley, California, USA). Seven normal faults with synfaulting, dip-slip striated calcite were studied and are from the following tectonic settings: a normal fault slip surface in an Ordovician Piedmont fold, Appalachian’s; paleo-subduction associated with Cretaceous metamorphic core complex formation (China, 3 sites); the paleo-extensional Atlantic margin (~ 55 Ma, Ireland, 1 site with a U–Pb calcite age); continental extension (1 active site, Mojave desert); a transcurrent margin (Jamaica, 1 active fault site), and subduction [2 active faults along the Eur-African margin in Italy (with calcite U–Th disequilibria ages) and Crete, respectively]. Six thrust fault examples are all from convergent orogenic settings: the basal thrust of the Penokean (1850 Ma) fold-and-thrust belt; the Penokean orogen foreland in Mesabi Range banded iron formation folds; an offset breccia body in the Permian Gondwanide belt, Ellsworth Mountains, Antarctica; the frontal thrust of the Gondwanide Cape belt, South Africa; the Paleocene frontal Prospect thrust, Sevier belt, Wyoming, and an Alpine foreland back-thrust, Lulworth Cove, U.K. For each strike-slip fault system the twinning shortening strain is horizontal and at an angle of 0°–60° to the respective fault plane (dextral or sinistral) although in the majority of cases the shortening axis is parallel to fault strike (13 of 23 results). In each normal fault example, dip-slip kinematic striations dominate the faulted surface yet the orientation of the maximum principal compressive stress (σ1) and shortening strain axis (ε1) are not 45° to the fault plane as predicted but are sub-horizontal and either strike-parallel (25 of 35 results) or strike-normal (10 of 35 results). Thrust faults preserve shortening strain axes parallel to the dip-slip kinematic direction, within the fault plane (plane strain) and not at 45° to the principal plane (5 of 5 results). None of the fault stress–strain field results reported here support the Andersonian or Mohr–Coulomb criteria for stress–strain relations predicted along faults.

Yield stress parameter derivation was conducted by stress-strain curve analysis on four types of grout injection leakage repair materials (GILRM); acrylic, epoxy, urethane and SPRG grouts. Comparative stress-strain curve analysis results showed that while the yield stress point was clearly distinguishable, the strain ratio of SPRG reached up to 664% (13 mm) before material cohesive failure. A secondary experimental result comprised of three different common component ratios of SPRG was conducted to derive and propose an averaged yield stress curve graph, and the results of the yield stress point (180% strain ratio) were set as the basis for repeated stress-strain curve analysis of SPRGs of up to 15 mm displacement conditions. Results showed that SPRG yield stress point remained constant despite repeated cohesive failure, and the modulus of toughness was calculated to be on average 53.1, 180.7, and 271.4 N/mm2, respectively, for the SPRG types. The experimental results of this study demonstrated that it is possible to determine the property limits of conventional GILRM (acrylic, epoxy and urethane grout injection materials) based on yield stress. The study concludes with a proposal on potential application of GILRM toughness by finite element analysis method whereby strain of the material can be derived by hydrostatic pressure. Comparative analysis showed that the toughness of SPRG materials tested in this study are all able to withstand hydrostatic pressure range common to underground structures (0.2 N/mm2). It is expected that the evaluation method and model proposed in this study will be beneficial in assessing other GILRM materials based on their toughness values.

The characterization of small-size engines requires dedicated rigs that are usually used for loading the power unit. Adding the possibility of motoring the engine is an important advantage that allows more detailed information on operating characteristics. It can be used for obtaining precious data that contribute to the development of more accurate numerical models and subsequent validation. Cost competitiveness is another essential aspect of small-size engines, given that development efforts need to be contained as much as possible. Within this context, the present work developed and tested a setup capable of cranking and motoring a small-size 50 cc spark ignition engine. Two configurations were considered for coupling an electric motor to the power unit: the first through a pulley-belt transmission and the second via a plastic clutch assembly. The main idea was to ensure the capability of motoring the engine up to a rotational velocity of 6000 rpm. Engine load was applied through a 1 kW electric generator connected directly to the crankshaft. The overall setup was designed in the two configurations and a stress–strain analysis was performed. The belt-driven option was found to be more favorable in terms of mechanical component requirements, showing a safety factor of around 4.0, while the plastic clutch assembly involved a more complex design phase and turned out to be more demanding, with a safety factor of around 2.9.

Background Fibrofatty degeneration of myocardium in ARVC is associated with wall motion abnormalities. The aim of this study was to examine whether Cardiovascular Magnetic Resonance (CMR) based strain analysis using feature tracking (FT) can serve as a quantifiable measure to confirm global and regional ventricular dysfunction in ARVC patients and support the early detection of ARVC. Methods We enrolled 20 patients with ARVC, 30 with borderline ARVC and 22 subjects with a positive family history but no clinical signs of a manifest ARVC. 10 healthy volunteers (HV) served as controls. 15 ARVC patients received genotyping for Plakophilin-2 mutation (PKP-2), of which 7 were found to be positive. Cine MR datasets of all subjects were assessed for myocardial strain using FT (TomTec Diogenes Software). Global strain and strain rate in radial, circumferential and longitudinal mode were assessed for the right and left ventricle. In addition strain analysis at a segmental level was performed for the right ventricular free wall. Results RV global longitudinal strain rates in ARVC (−0.68 ± 0.36 sec −1 ) and borderline ARVC (−0.85 ± 0.36 sec −1 ) were significantly reduced in comparison with HV (−1.38 ± 0.52 sec −1 , p ≤ 0.05). Furthermore, in ARVC patients RV global circumferential strain and strain rates at the basal level were significantly reduced compared with HV (strain: –5.1 ± 2.7 vs. -9.2 ± 3.6%; strain rate: –0.31 ± 0.13 sec –1 vs. -0.61 ± 0.21 sec –1 ). Even for patients with ARVC or borderline ARVC and normal RV ejection fraction (n=30) global longitudinal strain rate proved to be significantly reduced compared with HV (–0.9 ± 0.3 vs. -1.4 ± 0.5 sec –1 ; p < 0.005). In ARVC patients with PKP-2 mutation there was a clear trend towards a more pronounced impairment in RV global longitudinal strain rate. On ROC analysis RV global longitudinal strain rate and circumferential strain rate at the basal level proved to be the best discriminators between ARVC patients and HV (AUC: 0.9 and 0.92, respectively). Conclusion CMR based strain analysis using FT is an objective and useful measure for quantification of wall motion abnormalities in ARVC. It allows differentiation between manifest or borderline ARVC and HV, even if ejection fraction is still normal.

Creep refers to the deformation of rock with time under long-term applied stress, which occurs in most underground engineering. The creep behavior of granite in Shuangjiangkou underground powerhouse in Western Sichuan Province, China, was studied by creep tests. Based on test results, a new parameter DPR, the ratio of deviatoric stress to peak strength, is proposed. DPR is found to be a key parameter to describe creep parameters such as instantaneous elastic modulus, creep elastic modulus, and viscosity coefficient of rock under different confining pressures. Creep tests show that instantaneous elastic modulus increases with the increase of DPR. Creep elastic modulus increases when DPR changes from 0.54 to 0.7004, but decreases when DPR is from 0.7004 to 0.88, indicating fractures in rock closes first and then new fractures are generated. The viscosity coefficient of the rock increases first and then decreases with the increase of DPR, and when DPR = 0.7171, viscosity coefficient is maximum, indicating the time for the rock to reach stability is the longest in creep tests. By introducing DPR and confining pressure into the creep model, which interconnects creep parameters in a unified expression, an improved generalized Kelvin creep model is proposed which can accurately describe the primary and the secondary creep behavior of granite under given deviatoric stresses and confining pressures.