Abstract:Influences of the increasing pressure of climate change and anthropogenic activities on wetlands ecosystems and agriculture are significant around the world. This paper assessed the spatiotemporal land use and land cover changes (LULCC), especially for conversion from marshland to other LULC types (e.g., croplands) over the Songnen and Sanjiang Plain (SNP and SJP), northeast China, during the past 35 years . The relative role of human activities and climatic changes in terms of their impacts on wetlands and agriculture dynamics were quantitatively distinguished and evaluated in different periods based on a seven-stage LULC dataset. Our results indicated that human activities, such as population expansion and socioeconomic development, and institutional policies related to wetlands and agriculture were the main driving forces for LULCC of the SJP and SNP during the past decades, while increasing contributions of climatic changes were also found. Furthermore, as few studies have identified which geographic regions are most at risk, how the future climate changes will spatially and temporally impact wetlands and agriculture, i.e., the suitability of wetlands and agriculture distributions under different future climate change scenarios, were predicted and analyzed using a habitat distribution model (Maxent) at the pixel-scale. The present findings can provide valuable references for policy makers on regional sustainability for food security, water resource rational management, agricultural planning and wetland protection as well as restoration of the region.

This report describes the epitaxial growth and fabrication of room-temperature InAs0.89Sb0.11/InAs0.48Sb0.22P0.30 semiconductor light emitting diodes operating in the mid-infrared wavelength region near 4.5 µm. The InAs0.89Sb0.11 ternary material used in the light emitting diode active region has a large lattice mismatch with respect to the InAs substrate layer and in order to accommodate this it was necessary to grow a buffer layer with an intermediate composition (InAs0.94Sb0.06). The devices exhibit infrared emission at 4.5 µm and could be effectively used as the basis of an optical sensor for the environmental monitoring of carbon monoxide at 4.6 µm and carbon dioxide at 4.2 µm in various applications.

In this paper, we report the growth of very pure InAs epitaxial layers of high quantum efficiency, by introducing the rare-earth element Gd into the liquid phase during LPE growth. We find that the carrier concentration of InAs layers can be effectively reduced to ∼6 × 10 15 cm −3 . Also, the peak photoluminescence (PL) intensity of such layers can be considerably increased by between ten-and 100-fold compared with untreated material. We attribute this behaviour to the gettering of residual impurities and corresponding reduction of non-radiative recombination centres in the presence of Gd. Four intense sharp lines dominated the low temperature (4 K) photoluminescense spectra of Gd-treated InAs layers. The strongest two of these were found to originate from (a) bound excitons, and (b) donor-acceptor recombination, whereas the remaining two, (c) and (d), were associated with defect-related recombination. The linewidth (FWHM) of the exciton peak (a) was reduced to only 3.8 meV, which is narrower than for undoped epitaxial InAs grown by MBE or MOVPE.