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Ag3Sn intermetallic growth within Sn-Bi-Ag alloys during relatively slow cooling rates has a pronounced effect on the performance and reliability of solder joints. In this study, we combined experimental electron backscatter diffraction (EBSD) analysis with first-principles calculations to explore the crystal growth and faceting mechanisms of Ag3Sn intermetallic in solidifying Sn-xBi-1Ag (x = 10, 57 wt.%) alloys. Using EBSD techniques, accommodated for a pseudo-hexagonal setting of Ag3Sn to avoid pseudo-symmetry, and subsequent lattice transformation to an orthorhombic structure (a = 5.97 Å, b = 4.78 Å, c = 5.18 Å, Pmmn), this study reveals predominant (001)orth facets in Sn-10Bi-1Ag, and both (001)orth and more frequent (010)orth facets in Sn-57Bi-1Ag. Stability assessments of various crystal surfaces through first-principles calculations found the (010)orth surface to be most stable, followed by the (001)orth. Variations in stable facets between the two alloys may result from energy minimization influenced by atomic attachment at the liquid/solid interface, dynamic non-equilibrium solidification conditions, Bi concentration, and growth twinning. These findings enhance the understanding of intermetallic compound growth in solder alloys, with implications for solder joint technology improvement. [ABSTRACT FROM AUTHOR]

Thermal fatigue is a common failure mode in electronic solder joints, yet the role of microstructure is incompletely understood. Here, we quantify the evolution of microstructure and damage in Sn-3Ag-0.5Cu joints throughout a ball grid array (BGA) package using EBSD mapping of localised subgrains, recrystallisation and heavily coarsened Ag3Sn. We then interpret the results with a multi-scale modelling approach that links from a continuum model at the package/board scale through to a crystal plasticity finite element model at the microstructure scale. We measure and explain the dependence of damage evolution on (i) the β-Sn crystal orientation(s) in single and multigrain joints, and (ii) the coefficient of thermal expansion (CTE) mismatch between tin grains in cyclic twinned multigrain joints. We further explore the relative importance of the solder microstructure versus the joint location in the array. The results provide a basis for designing optimum solder joint microstructures for thermal fatigue resistance. [ABSTRACT FROM AUTHOR]

Eutectic Ag3Sn can grow with a variety of morphologies depending on the solidification conditions and plays an important role in the performance of Pb-free solders. Here, we study morphology transitions in the β-Sn + Ag3Sn eutectic at increasing growth velocity using a combination of real-time X-ray imaging and analytical electron microscopy. Orthorhombic Ag3Sn grew as faceted plates or rods with [010] growth direction and (001) as the largest facet in all three eutectic growth morphologies: Irregular plate, broken-lamellar, and rod. Reproducible β-Sn + Ag3Sn orientation relationships formed for the latter two morphologies. The mechanisms of spacing adjustment and the reversible transition from plate to rod growth are studied for transient solidification after velocity changes. The transition from fully eutectic growth to β-Sn dendrites plus eutectic is reasonably reproduced using a competitive growth criterion. At the highest velocities, Ag3Sn rods developed perturbations whose break down into particles is discussed in terms of unsteady growth and pinch-off mechanisms. [ABSTRACT FROM AUTHOR]

Manganese-bearing intermetallic compounds (IMCs) are important for limiting micro-galvanic corrosion of magnesium-aluminum alloys and can initiate cracks under tensile load. Here, we use electron backscatter diffraction (EBSD), deep etching, and focussed ion beam (FIB) tomography to investigate the types of Al-Mn phases present, their faceted growth crystallography, and their three-dimensional distribution at different locations in high-pressure die cast (HPDC) AZ91D. The Al-Mn particle size distributions were well-described by lognormal distributions but with an additional population of externally solidified crystals (ESCs) formed in the shot chamber analogous to α-Mg ESCs. The large Al8Mn5 particles were cyclic twinned. Differences in the particle size distributions and number density in the center compared with the HPDC skin are identified, and the spatial relationship between Mg17Al12 and Al-Mn particles is explored. [ABSTRACT FROM AUTHOR]

In recent years there has been increased interest in Bi-containing solders to improve the reliability of electronics and drive down processing temperatures. When the Bi content is more than ~ 2 wt% in Sn-Ag-Cu-Bi and Sn-Cu-Ni-Bi solders, (Bi) phase forms by a non-equilibrium eutectic reaction and also precipitates in the solid state. Here, we study the development of bismuth plates during room temperature storage in a range of Bi-containing solders. It is shown that Bi plates precipitate with one of two (Bi)-βSn orientation relationships (ORs). During coarsening the OR with the better lattice match grows at the expense of the other, leading to a single OR. The plate coarsening kinetics scale with the cube root of holding time and are relatively rapid, with plates exceeding 1 µm in length within 1 day at room temperature. Prolonged room temperature storage of more than 1 year resulted in Bi accumulation in 5-20 µm (Bi) particles at βSn grain boundaries. [ABSTRACT FROM AUTHOR]

A method is presented to control the size of primary CuSn in ball grid array (BGA) joints while keeping all other microstructural features near-constant, enabling a direct study of the size of primary CuSn on impact properties. For Sn-2Cu/Cu BGA joints, it is shown that larger primary CuSn particles have a clear negative effect on the shear impact properties. Macroscopic fracture occurred by a combination of the brittle fracture of embedded primary CuSn rods and ductile fracture of the matrix βSn. Cleavage of the CuSn rods occurred mostly along (0001) or perpendicular to (0001) with some crack deflection between the two. The deterioration of shear impact properties with increasing CuSn size is attributed to (1) the larger microcracks introduced by the brittle fracture of larger embedded CuSn crystals, and (2) the less numerous and more widely spaced rods when the CuSn crystals are larger, which makes them poor strengtheners. [ABSTRACT FROM AUTHOR]

Abstract Psoriasis is a complex chronic inflammatory skin disease with unclear molecular mechanisms. We found that the Src homology‐2 domain‐containing protein tyrosine phosphatase‐2 (SHP2) was highly expressed in both psoriatic patients and imiquimod (IMQ)‐induced psoriasis‐like mice. Also, the SHP2 allosteric inhibitor SHP099 reduced pro‐inflammatory cytokine expression in PBMCs taken from psoriatic patients. Consistently, SHP099 significantly ameliorated IMQ‐triggered skin inflammation in mice. Single‐cell RNA sequencing of murine skin demonstrated that SHP2 inhibition impaired skin inflammation in myeloid cells, especially macrophages. Furthermore, IMQ‐induced psoriasis‐like skin inflammation was significantly alleviated in myeloid cells (monocytes, mature macrophages, and granulocytes)—but not dendritic cells conditional SHP2 knockout mice. Mechanistically, SHP2 promoted the trafficking of toll‐like receptor 7 (TLR7) from the Golgi to the endosome in macrophages by dephosphorylating TLR7 at Tyr1024, boosting the ubiquitination of TLR7 and NF‐κB‐mediated skin inflammation. Importantly, Tlr7 point‐mutant knock‐in mice showed an attenuated psoriasis‐like phenotype compared to wild‐type littermates following IMQ treatment. Collectively, our findings identify SHP2 as a novel regulator of psoriasis and suggest that SHP2 inhibition may be a promising therapeutic approach for psoriatic patients.

The solidification of Pb-free solder joints is overviewed with a focus on the formation of the βSn grain structure and grain orientations. Three solders commonly used in electronics manufacturing, Sn-3Ag-0.5Cu, Sn-3.5Ag, and Sn-0.7Cu-0.05Ni, are used as case studies to demonstrate that (I) growth competition between primary dendrites and eutectic fronts during growth in undercooled melts is important in Pb-free solders and (II) a metastable eutectic containing NiSn forms in Sn-3.5Ag/Ni joints. Additionally, it is shown that the substrate (metallization) has a strong influence on the nucleation and growth of tin. We identify Co, Pd, and Pt substrates as having the potential to control solidification and microstructure formation. In the case of Pd and Pt substrates, βSn is shown to nucleate on the PtSn or PdSn intermetallic compound (IMC) reaction layer at relatively low undercooling of ~4 K, even for small solder ball diameters down to <200 μm. [ABSTRACT FROM AUTHOR]

Objective: It is important to distinguish between orbital cavernous haemangioma and schwannoma because the treatments of choice for the two tumours are different. The aim was to evaluate MR imaging findings distinguishing the two tumours.Methods: Magnetic resonance imaging including T1- and T2-weighted imaging and contrast-enhanced MR imaging was performed in 43 patients with cavernous haemangiomas and 16 patients with schwannomas confirmed by pathology. Location, configuration, margins, signal intensity, homogeneity and enhancement pattern of the tumour were retrospectively evaluated.Results: There was a significant difference between cavernous haemangiomas and schwannomas regarding the location, configuration and margins of the mass, signal intensity and homogeneity on T1- and T2-weighted imaging, the spread pattern of contrast enhancement, the enhancement pattern and the type of time-intensity curve (P<0.05). Markedly homogeneous hyperintensity signal on T2-weighted imaging and the spread pattern of the contrast enhancement favoured cavernous haemangioma rather than schwannoma (P<0.01).Conclusion: Cavernous haemangiomas and schwannomas have different MR imaging features that could be helpful in the differentiation between the tumours. The spread pattern of the contrast enhancement on dynamic contrast-enhanced MR imaging is the most reliable finding distinguishing cavernous haemangiomas from schwannomas. [ABSTRACT FROM AUTHOR]

Purpose: To prospectively evaluate magnetic resonance (MR) imaging including dynamic contrast-enhanced MR imaging in the differentiation of benign from malignant orbital masses and to evaluate which MR imaging features are most predictive of malignant tumors.Materials and Methods: The study was approved by the institutional review board and signed informed consent was obtained. Nonenhanced, static, and dynamic contrast-enhanced MR imaging was performed in 102 adult patients with an orbital mass. Diagnosis was based on histologic findings. MR imaging features of benign and malignant orbital lesions were evaluated correlated with histological findings. Multivariate logistic regression analysis was employed to identify the best combination of MR imaging features that might be predictive of malignancy.Results: Nonenhanced, static, and dynamic enhancement MR imaging was significantly superior to two other models in prediction of malignancy (p < 0.05). Multivariate logistic regression analysis identified that the most discriminating MR imaging features were isointense mass on T2-weighted imaging and a washout-type time-intensity curve for both observers.Conclusion: Nonenhanced, static, and dynamic enhancement MR imaging improved differentiation between benign and malignant orbital masses in adult patients. [ABSTRACT FROM AUTHOR]

The role of the transcriptional coactivator p300 in cell cycle control has not been analysed in detail due to the lack of appropriate experimental systems. We have now examined cell cycle progression of p300-deficient cancer cell lines, where p300 was disrupted either by gene targeting (p300− cells) or knocked down using RNAi. Despite significant proliferation defects under normal growth conditions, p300-deficient cells progressed rapidly through G1 with premature S-phase entry. Accelerated G1/S transition was associated with early retinoblastoma (RB) hyperphosphorylation and activation of E2F targets. The p300-acetylase activity was dispensable since expression of a HAT-deficient p300 mutant reversed these changes. Co-immunoprecipitation showed p300/RB interaction occurs in vivo during G1, and this interaction has two peaks: in early G1 with unphosphorylated RB and in late G1 with phosphorylated RB. In vitro kinase assays showed that p300 directly inhibits cdk6-mediated RB phosphorylation, suggesting p300 acts in early G1 to prevent RB hyperphosphorylation and delay premature S-phase entry. Paradoxically, continued cycling of p300− cells despite prolonged serum depletion was observed, and this occurred in association with persistent RB hyperphosphorylation. Altogether, these results suggest that p300 has an important role in G1/S control, possibly by modulating RB phosphorylation.Oncogene (2007) 26, 21–29. doi:10.1038/sj.onc.1209771; published online 31 July 2006 [ABSTRACT FROM AUTHOR]

Cellular senescence is a known driver of carcinogenesis and age-related diseases, yet senescence is required for various physiological processes. However, the mechanisms and factors that control the negative effects of senescence while retaining its benefits are still elusive. Here, we show that the rasGAP SH3-binding protein 1 (G3BP1) is required for the activation of the senescent-associated secretory phenotype (SASP). During senescence, G3BP1 achieves this effect by promoting the association of the cyclic GMP-AMP synthase (cGAS) with cytosolic chromatin fragments. In turn, G3BP1, through cGAS, activates the NF-κB and STAT3 pathways, promoting SASP expression and secretion. G3BP1 depletion or pharmacological inhibition impairs the cGAS-pathway preventing the expression of SASP factors without affecting cell commitment to senescence. These SASPless senescent cells impair senescence-mediated growth of cancer cells in vitro and tumor growth in vivo. Our data reveal that G3BP1 is required for SASP expression and that SASP secretion is a primary mediator of senescence-associated tumor growth. The mechanisms that control the deleterious behaviour of senescent cells is unclear. Here, the authors show that G3BP1 is required for the induction of the senescence-associated secretory phenotype (SASP), without affecting senescence, and that SASP secretion is a primary mediator of senescence-associated tumour growth. [ABSTRACT FROM AUTHOR]

The development of microstructure during melting, reactive wetting and solidification of solder pastes on Cu-plated printed circuit boards has been studied by synchrotron radiography. Using Sn-3.0Ag-0.5Cu/Cu and Sn-0.7Cu/Cu as examples, we show that the interfacial Cu6Sn5 layer is present within 0.05 s of wetting, and explore the kinetics of flux void formation at the interface between the liquid and the Cu6Sn5 layer. Quantification of the nucleation locations and anisotropic growth kinetics of primary Cu6Sn5 crystals reveals a competition between the nucleation of Cu6Sn5 in the liquid versus growth of Cu6Sn5 from the existing Cu6Sn5 layer. Direct imaging confirms that the β-Sn nucleates at/near the Cu6Sn5 layer in Sn-3.0Ag-0.5Cu/Cu joints. [ABSTRACT FROM AUTHOR]

Background: Laryngeal and hypopharyngeal squamous cell carcinoma (LHSCC) with thyroid cartilage invasion are considered T4 and need total laryngectomy. However, the accuracy of preoperative diagnosis of thyroid cartilage invasion remains lower. Therefore, the purpose of this study was to assess the potential of computed tomography (CT)-based radiomics features in the prediction of thyroid cartilage invasion from LHSCC., Methods: A total of 265 patients with pathologically proven LHSCC were enrolled in this retrospective study (86 with thyroid cartilage invasion and 179 without invasion). Two head and neck radiologists evaluated the thyroid cartilage invasion on CT images. Radiomics features were extracted from venous phase contrast-enhanced CT images. The least absolute shrinkage and selection operator (LASSO) and logistic regression (LR) method were used for dimension reduction and model construction. In addition, the support vector machine-based synthetic minority oversampling (SVMSMOTE) algorithm was adopted to balance the dataset and a new LR-SVMSMOTE model was constructed. The performance of the radiologist and the two models were evaluated with receiver operating characteristic (ROC) curves and compared using the DeLong test., Results: The areas under the ROC curves (AUCs) in the prediction of thyroid cartilage invasion from LHSCC for the LR-SVMSMOTE model, LR model, and radiologist were 0.905 [95% confidence interval (CI): 0.863 to 0.937)], 0.876 (95%CI: 0.830 to 0.913), and 0.721 (95%CI: 0.663-0.774), respectively. The AUCs of both models were higher than that of the radiologist assessment (all P < 0.001). There was no significant difference in predictive performance between the LR-SVMSMOTE and LR models (P = 0.05)., Conclusions: Models based on CT radiomic features can improve the accuracy of predicting thyroid cartilage invasion from LHSCC and provide a new potentially noninvasive method for preoperative prediction of thyroid cartilage invasion from LHSCC.