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In this paper, we present LaSOT, a high-quality benchmark for Large-scale Single Object Tracking. LaSOT consists of 1,400 sequences with more than 3.5M frames in total. Each frame in these sequences is carefully and manually annotated with a bounding box, making LaSOT the largest, to the best of our knowledge, densely annotated tracking benchmark. The average video length of LaSOT is more than 2,500 frames, and each sequence comprises various challenges deriving from the wild where target objects may disappear and re-appear again in the view. By releasing LaSOT, we expect to provide the community with a large-scale dedicated benchmark with high quality for both the training of deep trackers and the veritable evaluation of tracking algorithms. Moreover, considering the close connections of visual appearance and natural language, we enrich LaSOT by providing additional language specification, aiming at encouraging the exploration of natural linguistic feature for tracking. A thorough experimental evaluation of 35 tracking algorithms on LaSOT is presented with detailed analysis, and the results demonstrate that there is still a big room for improvements.

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A highly efficient approach of visible-light-driven radical difluoromethylation of isocyanides to access a wide variety of difluoromethylated phenanthridines and isoquinolines is herein described. Electrophilic S-(difluoromethyl)­diarylsulfonium salt proved to be a good difluoromethyl radical precursor under photoredox catalysis. A broad range of isocyanides were tolerated to furnish the corresponding difluoromethylated phenanthridines, isoquinolines, furo­[3,2-c]­pyridine, and pyrido­[3,4-b]­indole in moderate to excellent yields under mild conditions. A plausible mechanism was also proposed.

ZnGa2O4:Mn, as a distinct long persistent luminescence (PL) phosphor with green emission, has attracted intensive interest for display devices and security applications. We have systemically investigated the role of intrinsic defects in the PL of pristine and Mn doped ZnGa2O4 by first-principles calculations. It is found that the self-activated PL is attributed to the electron traps induced by VO and hole traps by VZn and ZnGa. The doped Mn will be energetically favored at the tetrahedral sites rather than octahedral sites under an Mn-rich condition. In contrast, the site preference of Mn largely depends on the chemical potentials of Zn and Ga under Mn-poor condition. The existence of the antisite defect ZnGa, however, promotes the stability of Mn at octahedral sites significantly, forming corresponding defect complexes. The crystal field strength is significantly enhanced, while the spin splitting is reduced on Mn in the defect complex, which introduces additional near-infrared luminescence of PL as confirmed by our experiment.

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The controllable incorporation of the dopant element with strictly designed coordination geometry into the target host merits untold scientific and technological potential, yet it has been met with limited success in a disordered matrix. Here, we present a general route for precisely tuning the coordination geometry of the transition metal dopant based on the collaborative element hybridization and crystallization. We experimentally realize the effective switch of tetrahedral and octahedral geometry by using the proof-of-concept Co 2+ dopant in hybrid glass. We identify that the crystal field stabilization energy should be genetic dominating the above process. The stabilization of high-yield [CoO 4 ] 6− tetrahedron and [CoF 6 ] 4− octahedron in glass enables it to exhibit unique photon−electron−photon effects, including the efficient radiative transition in the blind region of rare earth-doped materials from 2200 to 2600 nm with new record bandwidth (570 nm) and dynamic optical modulation for pulse generation with the duration of 280 ns. The results demonstrate that the proposed strategy provides an effective avenue to construct novel photonic components with multifunctional applications from broadband telecommunication, medical diagnostics, and military countermeasure to trace gas monitoring.

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