Evaluation of dark etching regions for standard bearing steel under accelerated rolling contact fatigue

Subsurface microstructural alterations are formed in the later stages of rolling contact fatigue (RCF) under high contact pressure. The subsurface changes observed as a dark contrast under optical microscopy are classified as Dark Etching Regions (DERs). Despite the fact that DERs have been presented for several decades, the understanding of its development and growth is yet to comprehend. Current research employed a modified high-speed microprocessor rotary tribometer to conduct systematic RCF study under accelerated testing conditions with variable temperatures and contact pressures. Comprehensive RCF data has been acquired, analysed and is reported for the very first time with ball-on-ball point contact loading conditions. The subsurface microscopic investigations have shown the ongoing progression and development of DER extent and are reported to be associated with the accumulation of plasticity during RCF. The comparison of the DER with the responsible stress components have revealed that DER formation is more closely related to the von Mises stresses when superposed with residual stresses. The experimentally observed area fraction of dark etching zones has been evaluated in terms of DER% and compared with the dislocation assisted carbon diffusion model for DER formation. The overprediction of the numerical model in comparison with the presented results in current research manifests its limitations which can be improved with the incorporation of cyclic plasticity governed by evolved von Mises stresses. Detailed evaluated DER results are presented as 3D DER% maps incorporating the combined effects of contact stress, temperature and rolling cycles simultaneously which enables an in-depth RCF understanding within microstructural context and therefore can be used as guidelines for DER formation models

Globalization and the Determinants of Innovation in BRICS versus OECD Economies: A Macroeconomic Study

This study examines the influence of select macroeconomic variables and globalization variables on the volume of patented innovations in five industrialized OECD countries (the U.S., the U.K., Germany, Japan, and Australia) and in five emerging countries known as BRICS (Brazil, Russia, India, China, and South Africa). The regression results indicate that trade openness has a more positive impact in boosting innovation in BRICS than in the five OECD countries, whereas ethnic diversity and R&D expenditure have a more positive influence on innovation activities in OECD countries than in BRICS. Surprisingly, despite popular presumption that the Internet has dramatically leveled the innovation playing field by making distant communication and idea pooling faster and cheaper, in our regression results, we find little support to the notion. It appears that emerging countries need to find new ways to leverage ethnic diversity and R&D expenditure as catalysts for innovation. A caveat to our findings is potential bias in our data, first from the choice of which countries to include but also from the quality and quantity of data within the countries. We must also keep in mind the potential socio-political factors behind the issuance of patents. However, we nonetheless believe this study to be an insightfully comparative exploration of some macro determinants of innovation

A 3D finite element model of rolling contact fatigue for evolved material response and residual stress estimation

Rolling bearing elements develop structural changes during rolling contact fatigue (RCF) along with the non-proportional stress histories, evolved residual stresses and extensive work hardening. Considerable work has been reported in the past few decades to model bearing material hardening response under RCF; however, they are mainly based on torsion testing or uniaxial compression testing data. An effort has been made here to model the RCF loading on a standard AISI 52100 bearing steel with the help of a 3D Finite Element Model (FEM) which employs a semi-empirical approach to mimic the material hardening response evolved during cyclic loadings. Standard bearing balls were tested in a rotary tribometer where pure rolling cycles were simulated in a 4-ball configuration. The localised material properties were derived from post-experimental subsurface analysis with the help of nanoindentation in conjunction with the expanding cavity model. These constitutive properties were used as input cyclic hardening parameters for FEM. Simulation results have revealed that the simplistic power-law hardening model based on monotonic compression test underpredicts the residual generation, whereas the semi-empirical approach employed in current study corroborated well with the experimental findings from current research work as well as literature cited. The presence of high compressive residual stresses, evolved over millions of RCF cycles, showed a significant reduction of maximum Mises stress, predicting significant improvement in fatigue life. Moreover, the predicted evolved flow stresses are comparable with the progression of subsurface structural changes and be extended to develop numerical models for microstructural alterations

Wave-dominated Shoreline Sediments in Early Cretaceous Surajdeval Formation, Saurashtra Basin, Gujarat Western India

The Early Cretaceous Surajdeval Formation of the Dhrangadhra group consists of the following three major facies: 1) a sand dominated facies (S), characterized by hummocky cross-stratification, planar and trough cross-bedding (Sp, St), and swaley cross stratification (SCS). 2) the hetro lithic facies (H) characterized by shatter red mudstone and fine-to very fine grained sandstone / red siltstone, exhibiting parallel and low-angle cross-laminations including symmetrical and interference ripples 3) sand matrix-supported conglomerate/pebbly facies (Cg-S) displaying an alternation of coarse (50mm), medium to fine (lt10-20 mm) pebbles in successive beds, and couplets of crudely graded conglomerate. nbspnbspnbspnbspnbsp The sedimentary facies and structures of the Surajdeval Formation reflect deposition by wave, and tide dominated events. Parallel-laminated and fine-grained sandstones are deposited in response to decrease incompetency and capacity of the flow. nbspnbspnbspnbspnbsp The conglomerates and couplets with sandstone may be the product of longshore deposits. Mudstone may have accumulated in protected lagoonal environment. Paleocurrent indicators, such as cross-bedding and pebble fabric show orientation toward south-south-west, and north-north-west, and may be attributed to ebb tidal (onshore), and those exhibiting north-north-west orientation to flood tidal/ longshore (off-shore) currents. Thus, the sedimentological features of the Surajdeval Formation suggest that wave tides and storm processes were involved during its deposition

4-[(Anthracen-9-yl­methyl­idene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

In the title compound, C26H21N3O, the phenyl ring of the 4-amino­anti­pyrine group and the heterocyclic five-membered ring along with its substituents, except for the N-bound methyl group (r.m.s. deviation = 0.0027 Å), form a dihedral angle of 54.20 (5)°. Two S(6) ring motifs are formed due to intra­molecular C—H⋯N and C—H⋯O hydrogen bonds. In the crystal, mol­ecules are linked into supra­molecular chains along the a-axis direction via C—H⋯O contacts

2-[(2-Chloro­benzyl­idene)amino]-4,5,6,7-tetra­hydro-1-benzothio­phene-3-carbonitrile

In the title compound, C16H13ClN2S, the mean planes fitted through all non-H atoms of the heterocyclic five-membered and the benzene rings are oriented at a dihedral angle of 5.19 (7)°. In the crystal, a weak C—H⋯π inter­action occurs, along with weak π–π inter­actions [cenroid–centroid distance = 3.7698 (11) Å]

Lafora Disease Masquerading as Hepatic Dysfunction

Lafora disease is fatal intractable progressive myoclonic epilepsy. It is frequently characterized by epileptic seizures, difficulty walking, muscle spasms, and dementia in late childhood or adolescence. We chronicle here an unusual case of an asymptomatic young male soccer player who presented with elevated liver enzymes. Neurological examination was unremarkable. The diagnostic workup for hepatitis, infectious etiologies, autoimmune disorders, hemochromatosis, Wilson\u27s disease, alpha-1 antitrypsin deficiency, and other related diseases was inconclusive. He subsequently underwent an uneventful percutaneous liver biopsy. Based on the pathognomonic histopathological findings, Lafora disease was considered the likely etiology. The present study is a unique illustration of this rare disorder initially manifesting with abnormal liver enzymes. It underscores the importance of clinical suspicion of Lafora disease in cases with unexplained hepatic dysfunction. Prompt liver biopsy and genetic testing should be performed to antedate the onset of symptoms in these patients

(2Z)-2-(4-Methyl­phen­yl)-3-(2-naphth­yl)prop-2-enenitrile

In the title compound, C20H15N, the dihedral angle between the naphthalene and benzene rings is 60.30 (16)°. The crystal packing features very weak inter­molecular C—H⋯π inter­actions