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Understanding and controlling the photoexcited quasiparticle (QP) dynamics in monolayer (ML) transition metal dichalcogenides (TMDs) lays the foundation for exploring the strongly interacting, nonequilibrium two-dimensional (2D) QP and polaritonic states in these quantum materials and for harnessing the properties emerging from these states for optoelectronic applications. In this study, scanning tunneling microscopy/spectroscopy (STM/scanning tunneling spectroscopy) with light illumination at the tunneling junction is performed to investigate the QP dynamics in ML MoS 2 on an Au(111) substrate with nanoscale corrugations. The corrugations on the surface of the substrate induce nanoscale local strain in the overlaying ML MoS 2 single crystal, which result in energetically favorable spatial regions where photoexcited QPs, including excitons, trions, and electron-hole plasmas, accumulate. These strained regions exhibit pronounced electronic bandstructure renormalization as a function of the photoexcitation wavelength and intensity as well as the strain gradient, implying strong interplay among nanoscale structures, strain, and photoexcited QPs. In conjunction with the experimental work, we construct a theoretical framework that integrates nonuniform nanoscale strain into the electronic bandstructure of a ML MoS 2 lattice using a tight-binding approach combined with first-principle calculations. This methodology enables better understanding of the experimental observation of photoexcited QP localization in the nanoscale strain-modulated electronic bandstructure landscape. Our findings illustrate the feasibility of utilizing nanoscale architectures and optical excitations to manipulate the local electronic bandstructure of ML TMDs and to enhance the many-body interactions of excitons, which is promising for the development of nanoscale energy-adjustable optoelectronic and photonic technologies, including quantum emitters and solid-state quantum simulators for interacting exciton polaritons based on engineered periodic nanoscale trapping potentials.

Objectives: While useful in diagnosing angiosarcomas, CD31 can also highlight histiocytes within soft tissue tumors and lead to errors in diagnosis. We sought to determine how often CD31 highlights cutaneous histiocytomas and histiocytoma mimics., Methods: We examined eight epithelioid cell histiocytomas (ECHs), 12 xanthogranulomas (XGs), nine cases of Langerhans cell histiocytosis (LCH), eight reticulohistiocytomas, 11 xanthomas, 29 atypical fibroxanthomas, nine granular cell tumors, four cases of angiolymphoid hyperplasia with eosinophilia, nine intradermal Spitz nevi, and nine angiosarcomas with antibodies directed against CD31, CD34, CD163, and factor VIII., Results: CD31 marked cells in three of 12 XGs, four of nine cases of LCH, one of eight reticulohistiocytomas, one of 11 xanthomas, 10 of 29 atypical fibroxanthomas, four of four cases of angiolymphoid hyperplasia with eosinophilia, nine of nine angiosarcomas, zero of nine granular cell tumors, and zero of eight ECHs. CD34 and factor VIII were negative in all nonvascular cases., Conclusions: Our results indicate that CD31 can mark lesional cells and imitate vascular tumors in cutaneous histiocytomas and histiocytoma mimics, an error that can be avoided by using a panel of antibodies., (Copyright© by the American Society for Clinical Pathology.)

Although in most cases one can easily distinguish between atypical fibroxanthomas and angiosarcomas, hemorrhagic atypical fibroxanthomas can pose a diagnostic problem. In rare cases, the large atypical cells of atypical fibroxanthoma can stain with CD31, leading to the erroneous diagnosis of angiosarcoma. We elected to further study this conundrum with 2 additional markers of lymphatic and vascular elements, namely D2-40 (podoplanin) and Fli-1, respectively. We studied 26 cases of atypical fibroxanthoma and 20 cases of angiosarcoma with Fli-1 and D2-40. We found that both Fli-1 and D2-40 stained a majority of cases of angiosarcoma (16/20 and 12/20, respectively), although only staining a minority of cases of atypical fibroxanthoma (8/26 for both). In addition, D2-40 staining of atypical fibroxanthoma was usually weak when positive, whereas Fli-1 staining of angiosarcomas was mostly strong and nuclear. Thus, both D2-40 and Fli-1 seem to be useful in distinguishing between atypical fibroxanthomas and angiosarcomas.