1,721,483 research outputs found
Investigation on the effect of the gas-to-metal ratio on powder properties and PBF-LB/M processability
Full text linkMetal powders for the laser powder bed fusion process are usually produced via gas atomization. However, due to the tight particle size distribution required for this application, the yield of the atomization process is low, resulting in a high-powder cost. In this work, atomization process parameters were varied to increase the gas-to-metal ratio to reduce the particle size distribution produced, and therefore increase the yield of the process. As a result, eight powders were produced starting from scrap AISI 136L material at different gas-to-metal ratio values, and the atomization process yield was successfully increased by 50%. First, the eight powders were characterized in terms of powder size, shape distributions, and flowability. Later, all powders were used to produce tensile specimens. The powders produced at higher yield exhibited a larger number of fine particles but slightly lower circularity, particularly in the coarse fraction. Furthermore, powders produced at a high gas-to-metal ratio demonstrated enhanced flowing properties and higher packing density. Consequently, these powders exhibited superior tensile performance, with ultimate tensile strength (UTS) ranging from 651 to 673 MPa and elongation values between 63 and 66%
A neuro-dynamic programming approach to synthesize optimal dispatching rules in logistics
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Daratumumab-Based Therapy for IgM Multiple Myeloma With Hyperviscosity Syndrome: A Case Report
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Using recycled material to produce gas-atomized metal powders for additive manufacturing processes
Full text linkAdditive manufacturing refers to the technologies used to directly produce parts from a three-dimensional model. Recycled AISI 316L and standard AISI 316L materials were used to produce powders via gas atomization process, and two additive manufacturing technologies, i.e., selective laser melting and laser metal deposition, were investigated. This study aims to determine the feasibility of using recycled material to produce powders for additive manufacturing. For each technology, the effect of process parameters on the solidification of the recycled powders was evaluated. Then, tensile tests were conducted on the specimens produced using the optimized process parameters. Specimens from both the technologies exhibited higher ultimate tensile strength values than standard AISI 316L. Recycled powders made from selective laser melting and laser metal deposition exhibited tensile strength values of 653 ± 1.79 MPa and 675 ± 2 MPa, respectively, whereas the standard powders exhibited a tensile strength of 594 ± 0.89 and 585 ± 3.1 MPa, respectively. We conclude that recycled AISI 316L can be used to produce powders for AM applications, resulting in good processability and high mechanical properties
N- and K-ras oncogenes in plasma cell dyscrasias
No full textN- and K-ras oncogene mutations represent the most frequent molecular lesions in plasma cell dyscrasias. They are not randomly distributed since they are detectable in multiple myeloma (MM) (9-31%) and plasma cell leukemia (PCL) (30%), and not in monoclonal gammopathy of undetermined significance (MGUS) and solitary plasmacytoma (SP). Codons 12, 13 and 61 of N- and K-ras genes have been found mutated. Mutations affecting codon 61 of N-ras gene are the most frequent finding. A heterogeneous pattern of mutations is described with a prevalence of purine-pyrimidine transversions. Ras gene mutations have been predominantly detected in myelomas characterized by an advanced stage disease, and adverse prognostic parameters. These findings suggest that ras mutations represent a late molecular lesion and may be implicated in tumor progression rather than tumor initiation
MULTIPLE-MYELOMA - BIOLOGICAL AND CLINICAL-SIGNIFICANCE OF BONE-MARROW PLASMA-CELL LABELING INDEX
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