Abslracl. A stmclure for ordered silicon-tin syslems on a silimn substrate, based on the known StNCtUre of a monolayer of tin on the (111) face of silicon, is propased. The corresponding electronic struclure of this syslem is modelled using the local densiy approximation to the densily functional theory of lhe electron gas in the KohnSham formulation wilh ab initio pseudopotentials taken tor lhe eleclron-ion interaction. The total energy is minimized including relaxation of all the ionic positions, and the single electron states then evaluated. It is found that the overall energy gap in the band slruct~re decreases rapidly with increasing tin mncentralion, and the direct gap is only 0.6 eV larger than the indirecl gap for a tin concentralion of 0.17 (a silimn mncenlration of 0.83). Effective masses of lhe electrons and the holes are evaluated at a tin mncenlration of 0.17. ?he lighter holes and eleclrons are found to be of similar mass to tbme in silicon. However, heavy electrons and hales are also found in the layer structure.

Tumor spread is responsible for most deaths related to cancer. Increasing the accuracy of cancer prognosis is critical to reducing the high mortality rates in cancer patients. Here, we report that the electrostatic potential difference (EPD) between tumor and its paratumor tissue is a prognostic marker for tumor spread. This finding is concluded from the patient-specific EPD values and clinical observation. The electrostatic potential values were measured on tissue cryosections from 51 patients using Kelvin probe force microscopy (KPFM). A total of $44% (15/34) patients of V tumor-paratumor > 0 were featured with tumor spread, whereas only $18% (2/11) patients of V tumor-paratumor < 0 had tumor spread. Next, we found the increased enrichment of cancer stem cells in paratumors with lower electrostatic potentials using immunofluorescence imaging, which suggested the attribution of tumor spread to the galvanotaxis of cancer stem cells (CSCs) toward lower potential. The findings were finally validated in breast and lung spheroid models composed of differentiated cancer cells and cancer stem cells at the ratio of 1:1 and embedded in Matrigel dopped with negative-, neutral-and positive-charged polymers and CSCs prefer to spread out of spheroids to lower electrostatic potential sites. This work may inspire the development of diagnostic and prognostic strategies targeting at tissue EPDs and CSCs for tumor therapy.

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The choice of therapeutic agents remains an unsolved issue in the repair of spinal cord injury. In this work, various agents and configurations were investigated and compared for their performance in promoting nerve regeneration, including bead assembly and bulk gel of collagen and Matrigel, under acellular and cell-laden conditions, and cerebral organoid (CO) as the in vitro preorganized agent. First, in Matrigel-based agents and the CO transplantations, the recipient animal gained more axon regeneration and the higher Basso, Beattie, and Bresnahan (BBB) scoring than the grafted collagen gels. Second, new nerves more uniformly infiltrated into the transplants in bead form assembly than the molded chunks. Third, the materials loaded the neural progenitor cells (NPCs) or the CO implantation groups received more regenerated nerve fibers than their acellular counterparts, suggesting the necessity to transplant exogenous cells for large trauma (e.g., a 5 mm long spinal cord transect). In addition, the activated microglial cells might benefit from neural regeneration after receiving CO transplantation in the recipient animals. The organoid augmentation may suggest that in vitro maturation of a microtissue complex is necessary before transplantation and proposes organoids as the premium therapeutic agents for nerve regeneration.