Recycling and reuse of kerf-loss silicon from diamond wire sawing for photovoltaic industry.

With the rapid growth of the global photovoltaic (PV) industry, the waste from PV industry cannot be ignored, especially the solid wastes from silicon kerf loss and the used quartz crucibles from silicon casting. The silicon kerf loss during wafer sawing was nearly 160,000 tonnes and the used crucible waste was nearly 70,000 tonnes in 2017. With the transition of wafering technology from the slurry-based wire to diamond wire sawing, recycling and reuse of kerf-loss silicon have become more feasible due to the lower impurity contents. In this paper, we aimed to find a simple approach to recycle the kerf loss and identify the purity for reuse. We first analyzed the contents of the as-received kerf-loss silicon from the industry. Then, suitable acids and refining procedure were proposed. The metals, especially nickel, could be easily reduced to several ppmw, boron and phosphorous to sub-ppmw, and carbon to several hundred ppmw, while oxygen was less than 5 wt%. Although the purity of the recycled silicon was not sufficient for casting feedstock, it had a comparable purity of about 5 N with the commercial silicon nitride releasing agent and crucibles used in silicon casting for solar cells. Because the nitride crucibles could be reused a few times for casting, the used crucible waste could be significantly reduced as well.

Adaptive Phase-Field Modeling of Anisotropic Wetting with Line Tension at the Triple Junction.

Line tension could affect the contact angle at triple junction, especially in micro- to nanoscale wetting. We have developed an adaptive phase-field model to consider the line tension quantitatively. This model is coupled to the smoothed boundary method for treating the contact line with the solid phase, while the volume constraint is imposed. Our calculated contact angles are in good agreement with the modified Young's equation. Further examples are illustrated for the anisotropic wetting on hydrophilic/hydrophobic stripes and rectangular grooves.

Faceted ice growth in hydrophilic and hydrophobic channels.

This study is motivated by the cryo-preservation for tissues, which is related to the solidification of blood in a confined space. The morphological behavior of growing ice facet in 1.3 mm hydrophilic and hydrophobic channels is the focus of this study. Both DI water and KCl solution were solidified without seeds in the channels and the growing front facet was discussed in regards to contact angle, in-situ morphology, conductivity difference between two phases and solute segregation. For DI water, the formation of facets was observed during ice growth in both hydrophilic and hydrophobic channels and could be classified into two modes according to the local curvature of the interface. The facet was formed at different positions of the interface in hydrophilic and hydrophobic channels. Solutal segregation effect was taken into consideration to partially govern the interface morphology and the facet formation during solidification of the KCl solution. In addition, the growth rates of the ice growth with a facet were also compared and discussed.

Transgenic expression of human gp100 and RANTES at specific time points for suppression of melanoma.

The induction of strong cell-mediated immunity against targeted cancer cells is difficult, and often requires specific vaccination schema and the appropriate adjuvants to be effective. The chemokine RANTES has been studied as a vaccine adjuvant in cancer therapy, but specific applications remain to be determined. For gene-based vaccination against B16 melanoma in C57BL/6JNarl mice, initial priming with mouse RANTES cDNA followed 24 h later by human gp100 DNA vaccination, and later boosting with a viral vector expressing mRANTES and hgp100 strongly suppressed B16/hgp100 primary tumors and lung metastasis. The inclusion of mRANTES in this vaccination regimen gave significantly better suppression of tumor growth, substantially enhanced mouse survival, and led to greater cytotoxic activity of splenocytes against B16/hgp100 cells than vaccination against hgp100 alone. B16/hgp100 melanoma cells were resistant to the ligands TRAIL and FasL in vitro but sensitized to them in vivo owing to the priming effect of cytokines in response to vaccination. Our data demonstrate that co-vaccination with chemokine (mRANTES) and tumor-specific (hgp100) genes in a specific time sequence is more effective at suppressing tumor growth and metastasis than hgp100 alone, and this effect may be mediated by sensitization of tumor cells to death ligands.

Efficient phase field simulation of a binary dendritic growth in a forced flow.

Efficient quantitative phase field simulation using an adaptive finite volume method with an antisolutal trapping scheme is presented for a binary dendritic growth in a forced flow. For the case of no convection, the calculated results with different interface thickness are examined. It is found that with a proper antisolutal trapping flux, a thick interface, but smaller than the diffusion boundary layer, could be used and the solution could approach to the sharp-interface Gibbs-Thompson equation limit in almost all aspects quantitatively. Based on the concentration driving force obtained from the sharp-interface limit of the Wheeler-Boettinger-McFadden (WBM) model, the calculated results are in good agreement with the classic Oseen-Ivantsov solution for the concentration-driven growth in a forced flow. And the selection scaling factor also increases with the external flow as the theoretical prediction.

Adaptive phase field simulation of dendritic growth in a forced flow at various supercoolings.

An efficient finite volume method is developed for the phase-field simulation of two-dimensional dendritic growth in a forced flow at various supercoolings. The adaptive nature of the method allows the dendrite in a large domain to evolve secondary structures, even at low supercoolings. In addition to good agreement with previous calculations on the tip shape and speed, the effects of forced flow at various supercoolings are investigated and compared with the Oseen-Ivantsov solution and good agreement is found. The steady dendrite shape in all cases continues to have a self-affine nature and the invariant scaling parameters are in good agreement with the estimation.