Effect of the powder feedstock on the oxide dispersion strengthening of 316L stainless steel produced by laser powder bed fusion

In this study, the concept of enhancing the in-situ oxide precipitation in laser powder-bed fusion processed parts is investigated using powder produced by water and gas atomization. By using water-atomized 316L powder, compared to gas-atomized powder, more oxide precipitates were introduced into the microstructure with the intent to enhance the strength of the material, as an alternative path to oxide dispersion strengthened materials. The results showed that oxide precipitation was homogenous, with higher-number densities of oxides in the sample built using the water-atomized powder. The oxides were observed to be amorphous and enriched in Si and Cr. The average size of the oxides was ~56 nm. After an annealing heat-treatment at 900 \ub0C, the oxides were observed to remain within the microstructure with only minor changes in size and composition. Mechanical testing at room temperature and at elevated temperature did not show any increase in strength relative to the sample built using gas-atomized powder. However, it was shown that the use of water atomized powder in the L-PBF process provides a viable method of introducing and tailoring the number of oxide particles within a built component relative to a conventional gas atomized powder

Triaxiality in 48Cr

Rotational behavior inducing triaxiality is discussed for 48Cr in the cranked Nilsson-Strutinsky (CNS) model, as well as in the spherical shell model. It is shown that the low-spin region up to about I=8, has a prolate well-deformed shape. At higher spins the shape is triaxial with a "negative-gamma" deformation, that is, with rotation around the classically forbidden intermediate axis. By comparing calculated B(E2)-values and spectroscopic quadrupole moments in the CNS with spherical shell model results and experimental data, the triaxial rotation around the intermediate axis is confirmed.Comment: 9 pages, including 6 figures; submitted to Physics Letters

Effect of powder variability on laser powder bed fusion processing and properties of 316L

To date, the effects of powder properties, both physical and chemical, on the printed properties of as-built components is still a topic that is poorly understood. A contributing factor is the lack of relevant methods for evaluating the rheological properties of powder, or flowability. This study presents a review of different 316 L powder grades that were produced using various atomization techniques. The physical powder properties were evaluated using powder metallurgical techniques, a powder rheometer (FT4) and a rotating drum analyser (RPA). The results indicate that both the FT4 and RPA are suitable for powder characterization. However, the parameter selection for evaluation must be done keeping in mind the application, in this case thin layer powder spreading. It was found that all bulk powder density measurements, basic flow energy and the break energy were able to both differentiate between powder grades and predict how suitable the powder will be for the laser-based powder-bed fusion process. Despite some printability challenges of the water atomized grades at higher layer thicknesses, it was found that both gas atomized grades performed similarly despite minor differences in particle size distribution. Furthermore, powder variability did not show any detrimental effects on the resulting mechanical properties

Effect of atomization on surface oxide composition in 316L stainless steel powders for additive manufacturing

The initial oxide state of powder is essential to the robust additive manufacturing of metal components using powder bed fusion processes. However, the variation of the powder surface oxide composition as a function of the atomizing medium is not clear. This work summarizes a detailed surface characterization of three 316L powders, produced using water atomization (WA), vacuum melting inert gas atomization (VIGA), and nitrogen atomization (GA). X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy analyses were combined to characterize the surface state of the powders. The results showed that the surface oxides consisted of a thin (~4 nm) iron oxide (Fe2O3) layer with particulate oxide phases rich in Cr, Mn, and Si, with a varying composition. XPS analysis combined with depth‐profiling showed that the VIGA powder had the lowest surface coverage of particulate compounds, followed by the GA powder, whereas the WA powder had the largest fraction of particulate surface oxides. The composition of the oxides was evaluated based on the XPS analysis of the oxide standards. Effects of Ar sputtering on the peak positions of the oxide standards were evaluated with the aim of providing an accurate analysis of the oxide characteristics at different etch depths

Polarization Effects in Superdeformed Nuclei

A detailed theoretical investigation of polarization effects in superdeformed nuclei is performed. In the pure harmonic oscillator potential it is shown that when one particle (or hole) with the mass single-particle quadrupole moment q_{nu} is added to a superdeformed core, the change of the electric quadrupole moment can be parameterized as q_{eff}=e(bq_{nu}+a), and analytical expressions are derived for the two parameters, $a$ and $b$. Simple numerical expressions for q_{eff}(q_\nu}) are obtained in the more realistic modified oscillator model. It is also shown that quadrupole moments of nuclei with up to 10 particles removed from the superdeformed core of 152Dy can be well described by simply subtracting effective quadrupole moments of the active single-particle states from the quadrupole moment of the core. Tools are given for estimating the quadrupole moment for possible configurations in the superdeformed A 150-region.Comment: 28 pages including 9 figure

Health-related quality of life, assessed with a disease-specific questionnaire, in Swedish adults suffering from well-diagnosed food allergy to staple foods

BACKGROUND: Our aim was to investigate the factors that affect health related quality of life (HRQL) in adult Swedish food allergic patients objectively diagnosed with allergy to at least one of the staple foods cow’s milk, hen’s egg or wheat. The number of foods involved, the type and severity of symptoms, as well as concomitant allergic disorders were assessed. METHODS: The disease-specific food allergy quality of life questionnaire (FAQLQ-AF), developed within EuroPrevall, was utilized. The questionnaire had four domains: Allergen Avoidance and Dietary Restrictions (AADR), Emotional Impact (EI), Risk of Accidental Exposure (RAE) and Food Allergy related Health (FAH). Comparisons were made with the outcome of the generic questionnaire EuroQol Health Questionnaire, 5 Dimensions (EQ-5D). The patients were recruited at an outpatient allergy clinic, based on a convincing history of food allergy supplemented by analysis of specific IgE to the foods in question. Seventy-nine patients participated (28 males, 51 females, mean-age 41 years). RESULTS: The domain with the most negative impact on HRQL was AADR, assessing the patients’ experience of dietary restrictions. The domain with the least negative impact on HRQL was FAH, relating to health concerns due to the food allergy. One third of the patients had four concomitant allergic disorders, which had a negative impact on HRQL. Furthermore, asthma in combination with food allergy had a strong impact. Anaphylaxis, and particularly prescription of an epinephrine auto-injector, was associated with low HRQL. These effects were not seen using EQ-5D. Analyses of the symptoms revealed that oral allergy syndrome and cardiovascular symptoms had the greatest impact on HRQL. In contrast, no significant effect on HRQL was seen by the number of food allergies. CONCLUSIONS: The FAQLQ-AF is a valid instrument, and more accurate among patients with allergy to staple foods in comparison to the commonly used generic EQ-5D. It adds important information on HRQL in food allergic adults. We found that the restrictions imposed on the patients due to the diet had the largest negative impact on HRQL. Both severity of the food allergy and the presence of concomitant allergic disorders had a profound impact on HRQL

Total Rhythm in Three Dimensions: Towards a Motional Theory of Melodic Dance Rhythm in Swedish Polska Music

In this article I present an ethnotheory of the music/dance relationship in Swedish polska, based on dance fieldwork and interviews I have conducted with polska dance musicians. I discuss three mechanisms that these musicians use to communicate movement patterns to dancers: iteration (entrainment via repetition), metaphor (timbral weight conveying motional weight), and sympathy (musicians’ movements mapping dance movements). I then discuss how musicians use these mechanisms to control four motional parameters: pulsation (rate and consistency of tempo), lean (degree and direction of tilt over the dance axis) viscosity (level of perceived air resistance), and libration (degree and timing of vertical motion). The work is intended in part as a case study of how theories of both music and dance can benefit from a focused analysis of the relationship between those two domains, as well as how studies of music/dance relations can benefit from the application of ethnographic research techniques

Functional KV10.1 Channels Localize to the Inner Nuclear Membrane

Ectopically expressed human KV10.1 channels are relevant players in tumor biology. However, their function as ion channels at the plasma membrane does not totally explain their crucial role in tumors. Both in native and heterologous systems, it has been observed that a majority of KV10.1 channels remain at intracellular locations. In this study we investigated the localization and possible roles of perinuclear KV10.1. We show that KV10.1 is expressed at the inner nuclear membrane in both human and rat models; it co-purifies with established inner nuclear membrane markers, shows resistance to detergent extraction and restricted mobility, all of them typical features of proteins at the inner nuclear membrane. KV10.1 channels at the inner nuclear membrane are not all transported directly from the ER but rather have been exposed to the extracellular milieu. Patch clamp experiments on nuclei devoid of external nuclear membrane reveal the existence of channel activity compatible with KV10.1. We hypothesize that KV10.1 channels at the nuclear envelope might participate in the homeostasis of nuclear K+, or indirectly interact with heterochromatin, both factors known to affect gene expression