INFLUENCE OF CERAMIC PARTICLES ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SAC305 LEAD-FREE SOLDERING MATERIAL
ARCHIVES OF METALLURGY AND MATERIALS
Authors: Pal, Manoj Kumar; Gergely, G.; Koncz-Horvath, D.; Gacsi, Z.
In this study, silicon carbide (SiC) reinforced lead-free solder (SAC305) was prepared by the powder metallurgy method. In this method SAC305 powder and SiC powder were milled, compressed and sintered to prepare composite solder. The composite solders were characterized by optical and scanning electron microscopy for the microstructural investigation and mechanical test. Addition of 1.5 wt. % and 2 wt. % ceramic reinforcement to the composite increased compressive strengths and microhardness up to 38% and 68% compared to those of the monolithic sample. In addition, the ceramic particles caused an up to 55% decrease in the wetting angle between the substrate and the composite solder and porosity was always increased with increase of SiC particles.
Arsenosugar Phospholipids (As-PL) in Edible Marine Algae: An Interplay between Liquid Chromatography with Electrospray Ionization Multistage Mass Spectrometry and Phospholipases A(1) and A(2) for Regiochemical Assignment
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
Authors: Coniglio, Davide; Calvano, Cosima D.; Ventura, Giovanni; Losito, Ilario; Cataldi, Tommaso R., I
The chemical identity of arsenosugar phospholipids (AsPL) as mono-(i.e., lyso, L-As-PL) and diacyl-arsenosugar PL in four edible and common marine alga samples, such as nori (Porphyra spp.), wakame (Undaria pinnatifida), dulse (Palmaria palmata), and kombu (Saccharina japonica), was successfully investigated. Adopting negative polarity electrospray ionization (ESI), not common for As-PL, conjugated with hydrophilic interaction liquid chromatography (HILIC) and mass spectrometry (MS), performed either at low resolution using a linear ion trap (LIT) with sequential MSn (n = 2, 3) or at high resolution using a high-resolution/high-accuracy Fourier-transform MS (FTMS), based on an orbital trap instrument, more than 20 As-PL and 2 L-As-PL species were identified. The absence of As-PL standard compounds encouraged us to generate an in-house-built database of As-PL/L-As-PL for a rapid and simple classification. Despite their compositional diversity, tandem MS of deprotonated As-PL and L-As-PL ([M-H](-)) demonstrated the occurrence of a highly diagnostic product ion at m/z 389.0 ([AsC10H19O9P](-)). The fatty acid composition and distribution of As-PL were easily assigned on the basis of the ratio intensity between sn-1 and sn-2 product ions. Indeed, the preferential formation of [R1C3H5O4P]-ions over [R2C3H5O4P](-) ions, both containing the glycerol backbone, enabled the regiochemical assignment of As-PL. These outcomes were confirmed by MSn (n = 2, 3) analyses and using sn-1-and sn-2regioselective hydrolase enzymes (i.e., phospholipases A(1) and A(2)). The predominant As-PL's in samples of nori (red alga), wakame, and kombu (both brown algae) were identified as containing palmitic acyl chains (i.e., As-PL958 (As-PL 16:0/16:0) with ca. 66 +/- 3, 82 +/- 4, and 58 +/- 3% as relative abundances, respectively), while the main species in dulse (red alga) samples was As-PL982 (As-PL 18:1/16:1) at ca. 38 +/- 3%.