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We analyze several recently detected gamma-ray bursts (GRBs) with late X-ray flares in the context of late internal shock and late external shock models. We find that the X-ray flares in GRB 050421 and GRB 050502B originate from late internal shocks, while the main X-ray flares in GRB 050406 and GRB 050607 may arise from late external shocks. Under the(More)
A novel rapid synthesis of indoles from N-Ts-2-alkenylanilines has been described; the reaction involves a NIS-mediated cascade C-N bond formation/aromatization, and a series of indoles with various functional groups have been synthesized in good to excellent yields under mild conditions without any other additives or catalysts.
Flash memory is a kind of common storage device. Its characteristics of flexibility, low power, and so on offer excellent qualifications for embedded system and mobile system. But flash memory must be written after erasure operation, and the most important thing is that the erasure operation times are very limitable. For assurance of long time availability,(More)
It is believed that orphan afterglow searches can help to measure the beaming angle in gamma-ray bursts (GRBs). Great expectations have been put on this method. We point out that the method is in fact not as simple as we originally expected. Due to the baryon-rich environment that is common to almost all popular progenitor models, there should be many(More)
A facile synthetic approach to a series of chiral 4-chloromethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one derivatives has been described. This transformation is achieved through the catalytic asymmetric chlorocyclization of 2-vinylphenylcarbamates using a newly developed organocatalyst. Furthermore, the resulting products can be easily converted into diverse(More)