Microwatts continuous-wave pumped second harmonic generation in few- and mono-layer GaSe.

We demonstrate the first achievement of continuous-wave (CW) pumped second harmonic generation (SHG) in few- and mono-layer gallium selenide (GaSe) flakes, which are coated on silicon photonic crystal (PC) cavities. Because of ultrahigh second order nonlinearity of the two-dimensional (2D) GaSe and localized resonant mode in the PC cavity, SHG's pump power is greatly reduced to microwatts. In a nine-layer GaSe coated PC cavity, while the optical power inside the GaSe flake is only 1.5% of that in the silicon PC slab, the SHG in GaSe is more than 650 times stronger than the third harmonic generation in silicon slab, indicating 2D GaSe's great potentials to strengthen nonlinear processes in silicon photonics. Our study opens up a new view to expand 2D materials' optoelectronic applications in nonlinear regime and chip-integrated active devices.

Utilisation of adsorption and desorption for simultaneously improving protein crystallisation success rate and crystal quality.

High-quality protein crystals of suitable size are an important prerequisite for applying X-ray crystallography to determine the 3-dimensional structure of proteins. However, it is often difficult to obtain protein crystals of appropriate size and quality because nucleation and growth processes can be unsuccessful. Here, we show that by adsorbing proteins onto porous polystyrene-divinylbenzene microspheres (SDB) floating on the surface of the crystallisation solution, a localised high supersaturation region at the surface of the microspheres and a low supersaturation region below the microspheres can coexist in a single solution. The crystals will easily nucleate in the region of high supersaturation, but when they grow to a certain size, they will sediment to the region of low supersaturation and continue to grow. In this way, the probability of crystallisation and crystal quality can be simultaneously increased in a single solution without changing other crystallisation parameters.

[Wooly-necked stork, a new bird record of China].

A new record species-the woolly-necked stork (Ciconia episcopus)-for China has been detected during a field survey of Shangri-La county, Diqing Tibetan autonomous prefecture, Yunnan province, June 10th, 2011. Ciconia episcopus is the least concern spices according to IUCN.

[Roosting-site characteristics of wintering black-necked cranes (Grus nigricollis) at Napahai, Yunnan].

From November 2009 to April 2010, roosting-site characteristics of black-necked cranes (Grus nigricollis) were observed at Napahai Provincial Nature Reserve, Shangri-La, Yunnan, China. The positions of roosting-sites were determined by triangulation with markers and field correction. All of the 63 roosting-sites observed were located in patchy marshes with water, which contained some mud on the bottom and 81% of the roosting-sites were covered by plants. They also had a certain distance to areas of human activities and had a certain distance to the shore. A comparison of roosting sites and random sites showed that roosting-sites had thicker mud layers, a higher ratio of open water, longer distance to roads, villages, and farmland, and water depth. Another comparison of before and after usage of roosting-sites found a significant difference in area of marsh patch. Principal component analysis indicated that the usage of roosting-site of black-necked cranes was affected by human disturbance, area of marsh patch, and the condition of the shallow water environment.