Welding fume nanoparticles from solid and flux-cored wires: Solubility, toxicity, and role of fluorides.

Welding fume particles are hazardous. Their toxicity likely depends on their composition and reactivity. This study aimed at exploring the role of sodium or other fluorides (NaF), which are intentionally added to flux-cored wire electrodes for stainless steel welding, on the solubility (in phosphate buffered saline) and toxicity of the generated welding fume particles. A multi-analytical particle characterization approach along with in-vitro cell assays was undertaken. The release of Cr(VI) and Mn from the particles was tested as a function of fluoride solution concentration. The welding fume particles containing NaF released significantly higher amounts of Cr(VI) compared with solid wire reference fumes, which was associated with increased cytotoxicity and genotoxicity in-vitro. No crystalline Na or potassium (K) containing chromates were observed. Cr(VI) was incorporated in an amorphous mixed oxide. Solution-added fluorides did not increase the solubility of Cr(VI), but contributed to a reduced Mn release from both solid and flux-cored wire fume particles and the reduction of Cr(VI) release from solid wire fume particles. Chemical speciation modeling suggested that metal fluoride complexes were not formed. The presence of NaF in the welding electrodes did not have any direct, but possibly an indirect, role in the Cr(VI) solubility of welding fumes.

Named Entity Recognition and Normalization Applied to Large-Scale Information Extraction from the Materials Science Literature.

The number of published materials science articles has increased manyfold over the past few decades. Now, a major bottleneck in the materials discovery pipeline arises in connecting new results with the previously established literature. A potential solution to this problem is to map the unstructured raw text of published articles onto structured database entries that allow for programmatic querying. To this end, we apply text mining with named entity recognition (NER) for large-scale information extraction from the published materials science literature. The NER model is trained to extract summary-level information from materials science documents, including inorganic material mentions, sample descriptors, phase labels, material properties and applications, as well as any synthesis and characterization methods used. Our classifier achieves an accuracy (f1) of 87%, and is applied to information extraction from 3.27 million materials science abstracts. We extract more than 80 million materials-science-related named entities, and the content of each abstract is represented as a database entry in a structured format. We demonstrate that simple database queries can be used to answer complex "meta-questions" of the published literature that would have previously required laborious, manual literature searches to answer. All of our data and functionality has been made freely available on our Github ( https://github.com/materialsintelligence/matscholar ) and website ( http://matscholar.com ), and we expect these results to accelerate the pace of future materials science discovery.

Size-separated particle fractions of stainless steel welding fume particles - A multi-analytical characterization focusing on surface oxide speciation and release of hexavalent chromium.

Welding fume of stainless steels is potentially health hazardous. The aim of this study was to investigate the manganese (Mn) and chromium (Cr) speciation of welding fume particles and their extent of metal release relevant for an inhalation scenario, as a function of particle size, welding method (manual metal arc welding, metal arc welding using an active shielding gas), different electrodes (solid wires and flux-cored wires) and shielding gases, and base alloy (austenitic AISI 304L and duplex stainless steel LDX2101). Metal release investigations were performed in phosphate buffered saline (PBS), pH 7.3, 37°, 24h. The particles were characterized by means of microscopic, spectroscopic, and electroanalytical methods. Cr was predominantly released from particles of the welding fume when exposed in PBS [3-96% of the total amount of Cr, of which up to 70% as Cr(VI)], followed by Mn, nickel, and iron. Duplex stainless steel welded with a flux-cored wire generated a welding fume that released most Cr(VI). Nano-sized particles released a significantly higher amount of nickel compared with micron-sized particle fractions. The welding fume did not contain any solitary known chromate compounds, but multi-elemental highly oxidized oxide(s) (iron, Cr, and Mn, possibly bismuth and silicon).

Note on ethene and other low-molecular weight hydrocarbons in environmental tobacco smoke.

Levels of ethene and propene, together with those of some other light hydrocarbons (propane, butane, isobutane and ethyne), have been measured under realistic conditions in environmental tobacco smoke (ETS) as a step towards the elucidation of the sources of 2-hydroxyethyl and 2-hydroxypropyl adducts of hemoglobin observed in non-smokers. These adducts may reflect in vivo doses of carcinogenic epoxides that are metabolites of the respective alkenes. The data show that 2.0 mg ethene, 1.4 mg propene, and 0.7 mg propane together with smaller amounts of butane, isobutane and ethyne are released per cigarette smoked (0.66 g tobacco) of a common Swedish brand. The alkenes in ETS should be considered as contributing factors to a risk of systemic cancer from passive smoking. With regard to alkene intake, even a relatively mild exposure to ETS (2 cigarettes per h for 5 h per day in a 33 m3 room with one air change per hour is estimated to correspond to the active smoking of about one cigarette per day.