Here, we report a real-time THz near-field microscope with a high dynamic range that can capture images of a 370 x 740 µm 2 area at 35 frames per second. We achieve high spatial resolution on a large area by combining two novel techniques: THz pulse generation by tilted-pulse-front excitation 7 and electrooptic (EO) balanced imaging detection using a thin crystal. To demonstrate the microscope capability, we reveal the field enhancement at the gap position of a dipole antenna after the irradiation of a THz pulse.Our results are the first demonstration of a direct quantification of a 2-dimensional subwavelength THz electric field taken in real-time.The very first demonstration of THz imaging 8 clarified that microscopic resolution is required for applications ranging from semiconductors inspections 9 to biomedical imaging 3,4 . For a corresponding wavelength at 1 THz, however, the far-field spatial resolution of an image is restricted to the Rayleigh criterion that corresponds to ∼180 µm in vacuum. To overcome this limit, we must work in the near-field region of a sample. In this case, the THz wave has to be captured very close to the sample surface in a region before light diffraction occurs 10 . Many schemes have been proposed since the first demonstration of THz near-field imaging 11 , most of which involve a subwavelength probe or a aperture placed very near the sample 9,11-17 .

Ru(NO)-salen complexes were found to catalyze asymmetric aerobic oxygen atom transfer reactions such as sulfide oxidation and epoxidation in the presence of water under visible light irradiation at room temperature. Oxidation of sulfides including alkyl aryl sulfides and 2-substituted 1,3-dithianes using complex 2 as the catalyst proceeded with moderate to high enantioselectivity of up to 98% ee, and epoxidation of conjugated olefins using complex 3 as the catalyst proceeded with good to high enantioselectivity of 76-92% ee. Unlike biological oxygen atom transfer reactions that need a proton and electron transfer system, this aerobic oxygen atom transfer reaction requires neither such a system nor a sacrificial reductant. Although the mechanism of this oxidation has not been completely clarified, some experimental results support the notion that an aqua ligand coordinated with the ruthenium ion serves as a proton transfer agent for the oxygen activation process, and it is recycled and used as the proton transfer mediator during the process. Thus, we have achieved catalytic asymmetric oxygen atom transfer reaction using molecular oxygen that can be carried out under ambient conditions.

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The broad diversity of neurons is vital to neuronal functions. During vertebrate development, the spinal cord is a site of sensory and motor tasks coordinated by interneurons and the ongoing neurogenesis. In the spinal cord, V2-interneuron (V2-IN) progenitors (p2) develop into excitatory V2a-INs and inhibitory V2b-INs. The balance of these two types of interneurons requires precise control in the number and timing of their production. Here, using zebrafish embryos with altered Notch signaling, we show that different combinations of Notch ligands and receptors regulate two functions: the maintenance of p2 progenitor cells and the V2a/V2b cell fate decision in V2-IN development. Two ligands, DeltaA and DeltaD, and three receptors, Notch1a, Notch1b, and Notch3 redundantly contribute to p2 progenitor maintenance. On the other hand, DeltaA, DeltaC, and Notch1a mainly contribute to the V2a/V2b cell fate determination. A ubiquitin ligase Mib, which activates Notch ligands, acts in both functions through its activation of DeltaA, DeltaC, and DeltaD. Moreover, p2 progenitor maintenance and V2a/V2b fate determination are not distinct temporal processes, but occur within the same time frame during development. In conclusion, V2-IN cell progenitor proliferation and V2a/V2b cell fate determination involve signaling through different sets of Notch ligand-receptor combinations that occur concurrently during development in zebrafish.

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