Accessing slip activity in high purity tin with electron backscatter diffraction and measurement of slip strength

Beta-tin has been used widely as an interconnect in modern electronics. To improve the understanding of the reliability of these components, we directly measure the critical resolved shear stress of individual slip systems in beta-tin using micropillar compression tests at room temperature with crystal orientations near-[100] and [001] in the loading direction within a large grain high purity tin (99.99%) sample. This activates the (110)[1-11]/2, (110)[1-1-1]/2, (010)[001] and (110)[001] slip systems. Analysis of the slip traces and load-displacement curves enables measurement of the critical resolved shear stress for epsilon=10^(-4) of tau_(CRSS)^({110}/2)=10.4+/-0.4 and tau_(CRSS)^({010})=3.9+/-0.3 MPa

Posterior Circulation Mechanical Thrombectomy through Primitive Trigeminal Artery: A Case Report

Introduction: Primitive trigeminal artery (PTA) is a rare intracranial vascular malformation, and mechanical thrombectomy and revascularization via PTA are rarely reported. Case Presentation: We reported a case of mechanical thrombectomy through PTA in a patient who presented with sudden slurred speech and had a National Institutes of Health Stroke Scale score of 12. Digital subtraction angiography of the cerebral vasculature showed PTA formation in the right internal carotid artery cavernous segment, with acute occlusion of the distal basilar artery at the PTA junction, and bilateral vertebral arteries and proximal basilar artery were underdeveloped. Therefore, we chose mechanical thrombectomy via PTA, but unfortunately, the vessel failed to recanalize. Follow-up at 1-month post-procedure indicated that the patient had passed away. We present the endovascular process and analyze and summarize the reasons for the failure to provide a reference for subsequent mechanical thrombectomy via PTA. Conclusions: PTA increases the risk of ischemic stroke and adds to the complexity of mechanical thrombectomy post-stroke. However, in certain situations, PTA can be used as a thrombectomy channel to increase the first-line possibility of timely endovascular treatment to save ischemic brain tissue

Observations of microstructure evolution and damage of SAC305 solder alloys during thermal and mechanical loadings

Creep of directionally solidified Sn-3Ag-0.5Cu wt.% dog-bone samples with a controlled or fibre texture is investigated under constant load tensile testing (stress level: 17 - 44 MPa) and at a range of temperatures (298 – 473 K). The tensile creep strain rate and the localised strain gradient are studied by two-dimensional optical digital image correlation. A transition of creep mechanisms from climb-controlled dislocation creep to lattice-limited diffusion creep is found beyond ~ T/T_M = 0.7 to 0.74 which changes depending on microstructure length-scale. The dominating creep mechanisms explored using electron backscatter diffraction, which enables the understanding of the heterogeneity in microstructural evolution at different strain levels, temperatures and strain rates. This heterogeneity is associated with grain boundaries and two distinct microstructural regions, i.e. the -Sn in dendrites and eutectic containing Ag3Sn and Cu6Sn5. Formation of subgrains and recrystallisation are observed with increasing strain levels, and these correlate with local lattice rotation. Tensile deformation of grains with [100] along the loading direction deform less than grains oriented with [110] along the loading direction. For [110] grains, the (11 ̅0)[001] slip system activates. For [100] grains, the (110)[11 ̅1]/2 and (11 ̅0)[1 ̅1 ̅1]/2 slip systems activate. The heterogeneous evolution of microstructure for a single Cu/SAC305/Cu solder joint is investigated using in-situ thermal cycling. Local deformation due to thermal mismatch results in heterogeneous lattice rotation, localised towards the corners of the Cu metal substrate and decreases towards the centre of the solder joint. This deformation is induced due to the constraint from the coefficient of thermal expansion mismatch between the β-Sn, Cu6Sn5 and Cu at the interface. Formation of subgrains with continuous increase in misorientation is revealed during deformation, implying that the accumulation of plastic slip at the strain-localised regions play a significant role in grain recrystallisation and crack nucleation which likely leads to joint failure.Open Acces

Predicting the DPP-IV Inhibitory Activity pIC50 Based on Their Physicochemical Properties

The second development program developed in this work was introduced to obtain physicochemical properties of DPP-IV inhibitors. Based on the computation of molecular descriptors, a two-stage feature selection method called mRMR-BFS (minimum redundancy maximum relevance-backward feature selection) was adopted. Then, the support vector regression (SVR) was used in the establishment of the model to map DPP-IV inhibitors to their corresponding inhibitory activity possible. The squared correlation coefficient for the training set of LOOCV and the test set are 0.815 and 0.884, respectively. An online server for predicting inhibitory activity pIC50 of the DPP-IV inhibitors as described in this paper has been given in the introduction