Neutral Radius Value Determination by Numerical Simulation Method at Ring Upsetting Test

Ring upsetting represents a basic operation for bulk forming process and has particular significance since it is used for contact friction determination. At ring upsetting by flat dies, metal flow depends upon tribological conditions present at contact surface. Thereby, two variants of metal flow are possible: a) two-way flow from neutral radius that is present at lower friction coefficient values, followed by ring’s inner radius reduction and ring’s outer radius increase. In such circumstances, neutral radius is found between inner and outer radius. b) one-way flow that occurs at higher friction coefficient values, where neutral radius is lower than ring’s inner radius. This paper is presenting the results of determination of relation between neutral radius value and friction coefficient. Such relation is determined by numerical simulation, by using Simufact.Forming software. Experimental verification of neutral radius position is conducted by metallographic analysis, for two friction coefficient values. Friction coefficient values are determined by ring upsetting by using dies, where in one case of ring upsetting, contact surfaces were ion implanted with nitroge

β-sheets Mediate the Conformational Change and Allosteric Signal Transmission Between the AsLOV2 Termini

Avena sativa phototropin 1 light-oxygen-voltage 2 domain (AsLOV2) is a model protein of Per-Arnt-Sim (PAS) superfamily, characterized by conformational changes in response to external environmental stimuli. This conformational change begins with the unfolding of the N-terminal A\u27α helix in the dark state followed by the unfolding of the C-terminal Jα helix. The light state is characterized by the unfolded termini and the subsequent modifications in hydrogen bond patterns. In this photoreceptor, β-sheets are identified as crucial components for mediating allosteric signal transmission between the two termini. Through combined experimental and computational investigations, the Hβ and Iβ strands are recognized as the most critical and influential β-sheets in AsLOV2\u27s allosteric mechanism. To elucidate the role of these β-sheets, we introduced 13 distinct mutations (F490L, N492A, L493A, F494L, H495L, L496F, Q497A, R500A, F509L, Q513A, L514A, D515V, and T517V) and conducted comprehensive molecular dynamics simulations. In-depth hydrogen bond analyses emphasized the role of two hydrogen bonds, Asn482-Leu453 and Gln479-Val520, in the observed distinct behaviors of L493A, L496F, Q497A, and D515V mutants. This illustrates the role of β-sheets in the transmission of the allosteric signal upon the photoactivation of the light state

Surface Roughness and Friction Coefficient at IBAD Deposited Tin Hard Coating

Influence of surface roughness of TiN coatings on friction and wear phenomena was investigated. Wear and friction properties were evaluated by using CSM nanotribometer. Relatively low load were used during testing, therefore wear depth was less than 20% of TiN coating thickness. Obtained results show that TiN coatings of higher hardness and lower friction coefficient can be produced by IBAD comparing to TiN coatings deposited by industrial PVD. Scaning electron and atomic force microscopy provide detailed analysis of nanochanges of wear zone morphology.Publishe

The role of sex in the pathophysiology of pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterised by increased pulmonary vascular resistance and pulmonary artery remodelling as result of increased vascular tone and vascular cell proliferation, respectively. Eventually, this leads to right heart failure. Heritable PAH is caused by a mutation in the bone morphogenetic protein receptor-II (BMPR-II). Female susceptibility to PAH has been known for some time, and most recent figures show a female-to-male ratio of 4:1. Variations in the female sex hormone estrogen and estrogen metabolism modify FPAH risk, and penetrance of the disease in BMPR-II mutation carriers is increased in females. Several lines of evidence point towards estrogen being pathogenic in the pulmonary circulation, and thus increasing the risk of females developing PAH. Recent studies have also suggested that estrogen metabolism may be crucial in the development and progression of PAH with studies indicating that downstream metabolites such as 16α-hydroxyestrone are upregulated in several forms of experimental pulmonary hypertension (PH) and can cause pulmonary artery smooth muscle cell proliferation and subsequent vascular remodelling. Conversely, other estrogen metabolites such as 2-methoxyestradiol have been shown to be protective in the context of PAH. Estrogen may also upregulate the signalling pathways of other key mediators of PAH such as serotonin

The Zwicky Transient Facility: System Overview, Performance, and First Results

The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg^2 field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope

Meconium stained amniotic fluid: Antenatal, intrapartum, postnatal management:review [Mekonyum Boyal Amniyotik Sv: Antenatal, ntrapartum, Postnatal Yönetim]

Approximately 13o of all live births are complicated by meconium stained amniotic fluid and only 5o of neonates born through of them develop meconium aspiration syndrome (MAS). In case of meconium stained amniotic fluid and respiratory distress MAS should be ruled out. Meconium aspiration may occur in utero or in first a few inspirations. Chronic fetal hypoxia and acidosis may cause fetal gasping and meconium aspiration in utero. Respiratory distress may ta ke place by the aspiration of meconium stained amniotic fluid in the nasopharynx of normal new born. Severity criteria for MAS are also defined. Mild MAS is a disease that requires less than 40o oxygen for less than 48 hours, moderate MAS is disease that requires more than 40o oxygen for mo re than 48 hours with no air leak, and severe MAS is a disease that requires assisted ventilation for more than 48 hours and is often associated with persistent pulmonary hypertension. The principal of prenatal management is to consider mecoium stained amniotic fluid as a sign of fetal distress and to follow closely the other signs of fetal distress. Intrapartum suctioning is not very effective and if the infant is vigorous defined as strong respiratory efforts, good muscle tone and a heart rate grea ter than 100 bpm, intubation and tracheal aspiration is not necessary. Pharmacotherapy of MAS in dude sedation and analgesia, pulmonary care, antibiotics, anti inflammatory agents and pulmonary vasodilators, surfactant and surfactant lavage. Copyright © 2012 by Türki ye Klinikleri

Primjena SEM i EDS analiza u istraživanju poroznosti Al-Si-Cu lijevanog stapa

Porosity formation was detected in the casting thinnest section in the proximity of the as cast surface and near the wall centerline. In order to investigate the cause of the porosity formation light microscopy was used to define as cast structure. After initial findings SEM and EDS analyses were performed. Based on the results it is possible to define cause of the observed porosity. A number of pores originates from the mould filling stage and entrainment of the oxide films, while others appear due to insufficient feeding during solidification.Kod najtanjeg presjeka stijenke odljevka otkrivena je pojava poroznosti neposredno ispod površine stijenke, kao i u zoni sredine stijenke. Kako bi se utvrdio uzrok pojave poroznosti primijenjena je svjetlosna mikroskopija za određivanje lijevane strukture. Nakon prvobitnih opažanja provedene su SEM i EDS analize. Na temelju dobivenih rezultata moguće je odrediti uzroke nastanka otkrivene poroznosti. Određeni broj pora nastaje zbog zarobljavanja oksidnog filma tijekom faze popunjavanja kalupa, dok je ostatak poroznosti posljedica neadekvatnog napajanja tijekom skrućivanja

Use of SEM and EDS analysis in the investigation of Al-Si-Cu piston alloy cast porosity

Porosity formation was detected in the casting thinnest section in the proximity of the as cast surface and near the wall centerline. In order to investigate the cause of the porosity formation light microscopy was used to define as cast structure. After initial findings SEM and EDS analyses were performed. Based on the results it is possible to define cause of the observed porosity. A number of pores originates from the mould filling stage and entrainment of the oxide films, while others appear due to insufficient feeding during solidification