48 research outputs found
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Solid-state joining of ultrahigh carbon steels
A joining study of these steels was initiated to determine the feasibility of using ultrahigh carbon steels in structural applications. The high carbon content (1.5 wt%) in these steels and the desire to maintain the superplastic microstructure limit the use of conventional arc-welding processes. We chose two solid-state joining processes: diffusion bonding and inertia friction welding. Preliminary results show that sound bonds can be obtained with tensile properties nearly equal to those of the base metal. Of three UHC steels bonded by both inertia-friction welding and diffusion- bonding processes, the one with the lowest aluminum content had the best overall properties. Diffusion bonding with a nickel interlayer showed the most promising results for the UHC steel containing 1.6 wt% aluminum. The properties of inertia-friction-welded steels can be improved by a post-weld heat treatment
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Weldment Mechanical Properties of Aluminum-Copper-Lithium Alloy, 2090, at Ambient and Cryogenic Temperatures
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Effects of Presipitate Distribution on 293 K and 77 K Properties of 2090-T81 Weldments
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Pre-Tinning and Flux Considerations of the Reliability of Solder Surface
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HIGH-MN STEEL WELDMENT MECHANICAL PROPERTIES AT 4 K
Advanced high-field superconducting magnets of the next generation of magnetic confinement fusion devices will require structural alloys with high yield strength and high toughness at cryogenic temperatures. Commercially available alloys used in the current generation of magnets, such as 300 series stainless steels, do not have the required properties. N-strengthened, high-Mn alloys meet base plate requirements in the as-rolled condition. However, the property changes associated with weld microstructural and chemical changes in these alloys have not been well characterized. In this work welding induced cryogenic mechanical property changes of an 18Mn-16Cr-5Ni-0.2N alloy are correlated with as-solidified weld microstructures and chemistries. 30 refs., 12 figs., 3 tabs
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Effect of Surface Condition on the Solderability of Pre-tinned Cu Sheet
Identification of an atypical etiological head and neck squamous carcinoma subtype featuring the CpG island methylator phenotype
Head and neck squamous cell carcinoma (HNSCC) is broadly classified into HNSCC associated with human papilloma virus (HPV) infection, and HPV negative HNSCC, which is typically smoking-related. A subset of HPV negative HNSCCs occur in patients without smoking history, however, and these etiologically ‘atypical’ HNSCCs disproportionately occur in the oral cavity, and in female patients, suggesting a distinct etiology.
To investigate the determinants of clinical and molecular heterogeneity, we performed unsupervised clustering to classify 528 HNSCC patients from The Cancer Genome Atlas (TCGA) into putative intrinsic subtypes based on their profiles of epigenetically (DNA methylation) deregulated genes.
HNSCCs clustered into five subtypes, including one HPV positive subtype, two smoking-related subtypes, and two atypical subtypes. One atypical subtype was particularly genomically stable, but featured widespread gene silencing associated with the ‘CpG island methylator phenotype’ (CIMP).
Further distinguishing features of this ‘CIMP-Atypical’ subtype include an antiviral gene expression profile associated with pro-inflammatory M1 macrophages and CD8+ T cell infiltration, CASP8 mutations, and a well-differentiated state corresponding to normal SOX2 copy number and SOX2OT hypermethylation. We developed a gene expression classifier for the CIMP-Atypical subtype that could classify atypical disease features in two independent patient cohorts, demonstrating the reproducibility of this subtype. Taken together, these findings provide unprecedented evidence that atypical HNSCC is molecularly distinct, and postulates the CIMP-Atypical subtype as a distinct clinical entity that may be caused by chronic inflammation