Narrow-linewidth microwave generation by an optoelectronic oscillator with a directly modulated microsquare laser.

A simple dual-loop optoelectronic oscillator using a 16 μm side length AlGaInAs/InP directly modulated microsquare laser is proposed and investigated without an external modulator. High-performance first harmonics are realized, with 3 dB linewidth, less than 200 Hz, and a frequency-tunable range from 2 to 8 GHz. Meanwhile, a side-mode suppression ratio of 60 dB is obtained for the microwave by the dual-loop structure.

An exo-β-(1→3)-D-galactanase from Streptomyces sp. provides insights into type II arabinogalactan structure.

An exo-β-(1→3)-D-galactanase (SGalase1) that specifically cleaves the β-(1→3)-D-galactan backbone of arabinogalactan-proteins (AGPs) was isolated from culture filtrates of a soil Streptomyces sp. Internal peptide sequence information was used to clone and recombinantly express the gene in E. coli.

Preparation of a new chromogenic substrate to assay for beta-galactanases that hydrolyse type II arabino-3,6-galactans.

A chromogenic assay using RB5-dGA, Reactive Black 5 (RB5) dye covalently coupled to de-arabinosylated gum arabic (dGA), was developed for rapid screening of beta-galactanases. dGA was prepared by partial acid hydrolysis (0.25M trifluoroacetic acid for 2h at 90-95 degrees C) of gum Arabic (GA) from Acacia senegal.

A nearly idealized 6'-O-methylated iota-carrageenan from the Australian red alga Claviclonium ovatum (Acrotylaceae, Gigartinales).

The polysaccharides extracted from Claviclonium ovatum were studied by a combination of compositional assays, reductive partial hydrolysis, linkage analysis, Fourier Transform infrared (FTIR) spectroscopy, and 13C, 1H, and 13C/1H heteronuclear multiple quantum correlation (HMQC) two-dimensional nuclear magnetic resonance (NMR) spectroscopy. The chemical and spectroscopic data showed that the alkali-modified C. ovatum polysaccharides are composed of a nearly idealized repeating unit of 6'-O-methylcarrabiose 2,4'-disulfate (the repeating unit of 6'-O-methylated iota-carrageenan), although some minor components were also present.