Polygonatone H,a new homoisoflavanone with cytotoxicity from Polygonatum Cyrtonema Hua.

A new homoisoflavonoid, (3R)-5,7-dihydroxy-6-methyl-3-(2′-hydroxy-4′-methoxybenzyl)-chroman-4-one (1), namely polygonatone H, in addition to fourteen known homoisoflavones (2–15) were isolated from the rhizome of Polygonatum Cyrtonema Hua. The structures were identified with the aid of 1D/2D NMR spectroscopic technologies. Compounds 2, 6, 8, 10, 11, 13, and 15 were isolated from P. Cyrtonema for the first time. Compound 1 showed cytotoxicities to human cancer cell lines with IC₅₀ values to comparable those of cisplatin.     

Compact eye-safe laser sources based on OPOs with KTP or PPKTP crystals

We report on compact eye-safe nanosecond laser sources emitting in the 1.5 μm wavelength range based on non-critically phase-matched parametric interaction in optical parametric oscillators (OPOs) with KTP and periodically poled KTP (PPKTP) crystals, pumped by the fundamental frequency of Nd:YAG lasers. As much as 250 μJ signal pulse energy at 1.5 μm wavelength, 6.5 ns FWHM pulse-width, has been obtained in a PPKTP-OPO, extracavity pumped by a Nd:YAG microlaser oscillator–amplifier at 650 μJ pump pulse energy, 8 ns pulse-width. A single signal pulse of 2.7-mJ output energy at 1.57 μm wavelength, less than 5 ns pulse-width, was generated in a KTP-OPO, intracavity pumped by a passively Q-switched Nd:YAG laser.     

Preliminary studies of material surface cleaning with a multi-pulse passively Q-switched Nd:YAG laser

A multi-pulse Q-switched (MPQ) Nd:YAG laser system for surface material cleaning has been developed. Trains of pulses having total output energy of as much as 1.05 J, 10–30 pulses/train, 20–70 ns individual pulse-width, and about 100 μs whole duration were generated. Ablation threshold fluence and ablation rate for limestone substrate have been measured and compared with the theoretical calculations. Safe surface cleaning of limestone samples was demonstrated thanks to the high gap between the ablation threshold fluence of the substrate and black crust. Tests of surface cleaning for samples of stone, ceramics, and metal were performed.     

In vivo imaging of dynamic biological specimen by real-time single-shot full-field optical coherence tomography

We demonstrate the feasibility of a compact single-shot full-field time domain optical coherence tomography (OCT) for imaging dynamic biological sample in real-time. The system is based on a Linnik type polarization Michelson interferometer and a four-quadrature phase-stepper optics, which can simultaneously capture four quadraturely phase-stepped interferograms on a single CCD. Using a superluminescent diode as light source with center wavelength of 842 nm and spectral width of 16.2 nm, the system yields an axial resolution of 19.8 μm, and covers a field of view of 280 × 320 μm² (220 × 250 pixels) with a transverse resolution of 4.4 μm by using a 10× microscope objective (0.3 NA). Three-dimensional OCT images of biological samples such as an onion slice and a diaptomus were obtained without any image averaging or pixel binning. In addition, in vivo depth resolved dynamic imaging was demonstrated to show the beating internal structure of a diaptomus with a fame rate of 5 fps.