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Effect of shoulder geometry on residual stress and fatigue properties of AA6082 fsw joints
M. De Giorgi,A. Scialpi,F.W. Panella,L.A.C. De Filippis 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.1
The tool geometry is a crucial characteristic of the friction stir welding (FSW) process; its design is the key to the successful FSW application for a wide range of materials and thicknesses improving the weld strength and fatigue life. The present study investigates the influence of three shoulder geometries on the FSW joint performance, in terms of residual stresses state, microhardness profile and mechanical properties of 1.5 mm thick AA 6082-T6 FSW joints in the butt-joint configuration. The three tool geometries are characterized by three different shoulders: a shoulder with scroll, a shoulder with a shallow cavity, and a flat shoulder. Transverse and longitudinal tensile tests at room temperature were performed in order to evaluate the mechanical properties, respectively, of the joints and of the stirred zone, while the fatigue tests were performed transversally to the joint line.
Common features in high Tc cuprates and diborides
A. Bianconi,S. Agrestini,G. Campi,M. Filippi,N. L. Saini 한국물리학회 2005 Current Applied Physics Vol.5 No.3
The normal state of magnesium diboride, the simplest metallic system showing the macroscopic quantum coherence at hightemperature (highTc superconductivityHTcS) shows some features that are common with the cuprates, shedding light on thepairing mechanism forTc amplication in HTcS: (1) two or more electronic components associated with multiple Fermi surfaceportions; (2) crossing of electronic topological transitions (ETT) where the Fermi surface changes its topology and (3) phononsoftening in extended Kohn anomalies (EKA) over a large wave-vector range..
Aging Alters Hepatic DNA Hydroxymethylation, as Measured by Liquid Chromatography/Mass Spectrometry
Stephanie A. Tammen,Gregory G. Dolnikowski,Lynne M. Ausman,Zhenhua Liu,김경철,Simonetta Filippi,최상운 대한암예방학회 2014 Journal of cancer prevention Vol.19 No.4
Background:Aging is one of the most important risk factors for cancer. It appears that aberrant epigenetic changes might be a commondriver of aging and cancer. Among them are changes in DNA methylation and DNA hydroxymethylation. The 5’ carbon of cytosinesin CpG dinucleotides of DNA can be either methylated or hydroxymethylated. Like 5’-methylcytosine, changes in 5’-hydroxymethylcytosinemay occur due to aging, potentially leading to downstream changes in transcription and cancer development. Methods:We set up a method to measure 5’-methyl-2’-deoxycytidine and 5’-hydroxymethyl-2’-deoxycytidine in DNA using liquidchromatography/mass spectrometry (LC/MS-MS) and used this method to measure the percentage of total cytosine that was eithermethylated or hydroxymethylated in the liver tissues of young and old C57Bl/6 male mice. The DNA was enzymatically hydrolyzed bysequential digestion with nuclease P1, phosphodiesterase I and alkaline phosphatase. The isotopomers [15N3]-2’-deoxycytidine and(methyl-d3, ring-6-d1)-5-methyl-2’-deoxycytidine were added to the DNA hydrolysates as internal standards. DNA methylation andhydroxymethylation were calculated as a percentage of total deoxycytidine in genomic DNA. Results:Within day variations for DNA methylation and hydroxymethylation were 3.45% and 8.40%, while day to day variations were6.14% and 17.68%, respectively. Using this method it was determined that hepatic DNA of old mice had increased levels ofhydroxymethylation relative to young (0.32 ± 0.02% vs. 0.24 ± 0.01%, P= 0.02), with no significant changes in 5’-methylcytosine. Conclusions:DNA hydroxymethylation measured by LC/MS-MS method can be a novel biomarker of aging. It will be useful to investigatethe potential role of DNA hydroxymethylation in the development and prevention of age-associated cancer.