Microstructural and shear strength properties of RHA-reinforced Sn–0.7Cu composite solder joints on bare Cu and ENIAg surface finish

In this study, the joint effect of rice husk ash (RHA) reinforcement as an alternative silica source and electroless nickel immersion silver (ENIAg) surface finish on the intermetallic compound (IMC) formation and shear strength of the Sn– 0.7Cu solder system was investigated. A series of plain and composite lead-free solder systems (Sn–0.7Cu−xRHA; x = 0, 0.01, 0.05 and 0.1 wt%) was successfully developed and subjected to reflow soldering on bare Cu and ENIAg surface finish. After conducting a comprehensive microstructural study using the scanning electron microscopy and energy dispersive spectroscopy techniques, the Cu6Sn5 and Cu3Sn intermetallic compound (IMC) phases were observed at the interface of the Sn–0.7Cu−xRHA/Cu composite solder joints. On the other hand, the (Cu,Ni)6Sn5 and Ni3Sn4 IMC phases dominated the interface of the Sn–0.7Cu−xRHA/ENIAg counterparts. Given the promising potential of the ENIAg surface finish, the Sn–0.7Cu−xRHA/ENIAg exhibited IMC thickness values within a range of 3.81–4.74 μm as compared to the 6.13–9.3 μm range exhibited by the Sn–0.7Cu−xRHA/Cu counterpart. More so, the ENIAg surface finish was effective in improving the shear strength of the plain solder joint, with the Sn–0.7Cu/ENIAg exhibiting 13.44 MPa relative to the 11.5 MPa exhibited by the Sn–0.7Cu/Cu counterpart. Overall, the strengthening effect of the RHA reinforcement was well marked in the Sn–0.7Cu−xRHA/Cu composite solder joints with the composite having 0.1 wt% RHA exhibiting the highest shear strength (14.6 MPa) across the board

The properties of slag-silica fume ternary blended mortar with quarry dust

High carbon emissions of manufactured Portland cement in the concrete industry have incurred several interests in reducing the use of Portland cement by partially replacing it with supplementary cementitious materials. Most of which, are by-products from other manufacturing industries. Hence, the main purpose of this study is to investigate the effects of different combinations of ternary blended mortars incorporating supplementary cementitious materials such as Ground Granulated Blast Furnace Slag (GGBS) and Densified Silica Fume (DSF). In this study, mortars were prepared with 100% quarry dust and GGBS was replaced with DSF at 2% step increments up to 16% at a w/b ratio of 0.24. At the same time OPC content was fixed at 50%. The compressive and flexural strength, drying shrinkage, and porosity of mortars were all tested. The results indicated that the increasing DSF content increases; GGBS reduces the superplasticizer dosage for the desired workability of the mortar. The utilization GGBS and DSF has improved the performances ternary blended mortar incorporating quarry dust as a fine aggregate in terms of mechanical strength, drying shrinkage and total porosity tested. The high strength ternary blended mortar incorporating GGBS and DSF exhibited optimum mechanical and durability performance at the OPC:GGBS:DSF ratio of 50:38:12

Shear analysis of rice husk ash RHA reinforced tin- 0.7-copper composite solders on electroless nickel/immersion silver ENIAg surfaces

In this study, the mechanical performance of the rice husk ash-reinforced tin-0.7 copper composite solder was investigated. 0.01 wt.%, 0.05 wt.% and 0.1 wt.% of rice husk ash (RHA) were added to the solder matrix to prepare the composite solders. In order, to replace the costly electroless nickel immersion gold surface finish on the copper substrate, the effect of electroless nickel immersion silver (ENIAg) as the surface finish was studied. The differential scanning calorimetry (DSC) analysis showed that the composite solder exhibited lower melting temperature relative to the plain solder owing to the inclusion of rice husk ash. Shear strength analysis was carried out to investigate the influence of rice husk ash and electroless nickel immersion silver surface finish on the shear strength of the developed composite solders. The results proved that the rice husk ash failed to enhance the shear strength of tin-0.7 copper lead-free solder with the plain solder exhibiting the highest shear strength

Maternal mosaicism in SSBP1 causing optic atrophy with retinal degeneration: implications for genetic counseling

Abstract Background Optic atrophy-13 with retinal and foveal abnormalities (OPA13) (MIM #165510) is a mitochondrial disease in which apparent bilateral optic atrophy is present and sometimes followed by retinal pigmentary changes or photoreceptors degeneration. OPA13 is caused by heterozygous mutation in the SSBP1 gene, associated with variable mitochondrial dysfunctions. Results We have previously reported a 16-year-old Taiwanese male diagnosed with OPA13 and SSBP1 variant c.320G>A (p.Arg107Gln) was identified by whole exon sequence (WES). This variant was assumed to be de novo since his parents were clinically unaffected. However, WES and Sanger sequencing further revealed the proband’s unaffected mother carrying the same SSBP1 variant with a 13% variant allele frequency (VAF) in her peripheral blood. That finding strongly indicates the maternal gonosomal mosaicism contributing to OPA13, which has not been reported before. Conclusions In summary, we described the first case of OPA13 caused by maternal gonosomal mosaicism in SSBP1. Parental mosaicism could be a serious issue in OPA13 diagnosis, and appropriate genetic counseling should be considered