Hydroxyl-Imidazolium Ionic Liquid-Functionalized MIL-101(Cr): A Bifunctional and Highly Efficient Catalyst for the Conversion of CO2 to Styrene Carbonate.

Considerable attention has been focused on the development of catalysts for the coupling reaction of carbon dioxide (CO2) and epoxides due to the distinct advantages and importance of this reaction. To develop high-performance and easy-to-recycle catalyst is still a hot topic, especially for candidates with excellent activity under moderate conditions. A new heterogeneous catalyst, MIL-101-ImEtOH, is reported by post-synthesis modification, in which 2-(1-imidazol-1-yl) ethanol (Im-EtOH) is immobilized on MIL-101(Cr). In the absence of solvent and co-catalyst, MIL-101-ImEtOH exhibits high activity for the cycloaddition of CO2 and styrene oxide. A 95.6% yield is achieved under 0.5 MPa CO2 pressure and 90 °C by utilization of 50 mg of catalyst for 3 h. Moreover, MIL-101-ImEtOH is easily separated from the catalytic system by simple filtration. To elucidate the influence of hydroxyl group and porous structure on catalysis, other two supported ionic liquids, MIL-101-EtIm and PS-ImEtOH, are prepared and used to catalyze the title reaction under the same conditions. The contribution of each active component is determined by density functional theory along with noncovalent interaction analysis.

Historical grassland desertification changes in the Horqin Sandy Land, Northern China (1985-2013).

Since rural reforms in the 1980s, both the state and local governments of China have devoted great efforts to combating desertification through a number of eco-environmental restoration campaigns, resulting in burgeoning contention at all levels of government and sparking public concern. Monitoring and accurately assessing the statuses and trends of grassland desertification are important for developing effective restoration strategies. The Horqin Sandy Land (HSL), a very typical desertified grassland (DG) with better hydrothermal conditions among sandy lands in north China, was recently selected (1985-2013) to assess the spatiotemporal dynamic performances of grassland desertification before and after implementing restoration projects. Landsat images (TM/ETM+/OLI), field investigations and expert review were integrated to form a classification scheme for the HSL. Then, spectral mixture analysis and the decision-tree method were used to extract bare-sand ratios and vegetation cover fraction dynamics. A favourable phenomenon of DG was seen to be reversed in an accelerated pace during 2001-2013, despite challenge from both climatic and anthropogenic factors. However, overexploitation of grassland (especially for farming) and ground water for irrigation has led to remarkable decreases in the ground water level in recent decades, which should be highly concerning regarding the formulation of restoration campaigns in the sandy land.

Distribution, congruence, and hotspots of higher plants in China.

Identifying biodiversity hotspots has become a central issue in setting up priority protection areas, especially as financial resources for biological diversity conservation are limited. Taking China's Higher Plants Red List (CHPRL), including Bryophytes, Ferns, Gymnosperms, Angiosperms, as the data source, we analyzed the geographic patterns of species richness, endemism, and endangerment via data processing at a fine grid-scale with an average edge length of 30 km based on three aspects of richness information: species richness, endemic species richness, and threatened species richness. We sought to test the accuracy of hotspots used in identifying conservation priorities with regard to higher plants. Next, we tested the congruence of the three aspects and made a comparison of the similarities and differences between the hotspots described in this paper and those in previous studies. We found that over 90% of threatened species in China are concentrated. While a high spatial congruence is observed among the three measures, there is a low congruence between two different sets of hotspots. Our results suggest that biodiversity information should be considered when identifying biological hotspots. Other factors, such as scales, should be included as well to develop biodiversity conservation plans in accordance with the region's specific conditions.

N-myc is a key switch regulating the proliferation cycle of postnatal cerebellar granule cell progenitors.

N-myc plays an important role in early cerebellar development; however, the role of N-myc in postnatal cerebellar development is still unknown. In this study, inducible and reversible N-myc mouse models (Nmyc(TRE/TRE):tTS and Nmyc(EGFP/TRE):tTS) are used to regulate and track the expression of endogenous N-myc in vivo. Loss of N-myc at the neonatal stage results in reduced proliferation of granule cell precursors (GCPs) and reduced cerebellar volume/mass. Restoration of N-myc expression no later than postnatal day 4 can rescue the cerebellar developmental defect caused by the absence of N-myc after birth. During cerebellar postnatal development, N-myc acts as a key switch, regulating the proliferation cycle of postnatal granule cell progenitors. Loss of N-myc significantly impairs the Sonic hedgehog signalling pathway, and disrupts the expression of cell cycle effectors with a significant reduction of Ccnd2. More importantly, N-myc negatively regulates the expression of microRNA-9 during postnatal cerebellar development. Our findings demonstrate that over-expression of miR-9 can inhibit the proliferation of GCPs. The regulation of these factors by N-myc is at least partly responsible for the switch role of N-myc in the proliferation cycle of GCPs.

Spatio-temporal variation in vegetation biomass and its relationships with climate factors in the Xilingol grasslands, Northern China.

Knowledge about grassland biomass and its dynamics is critical for studying regional carbon cycles and for the sustainable use of grassland resources. In this study, we investigated the spatio-temporal variation of biomass in the Xilingol grasslands of northern China. Field-based biomass samples and MODIS time series data sets were used to establish two empirical models based on the relationship of the normalized difference vegetation index (NDVI) with above-ground biomass (AGB) as well as that of AGB with below-ground biomass (BGB). We further explored the climatic controls of these variations. Our results showed that the biomass averaged 99.01 Tg (1 Tg=10(12) g) over a total area of 19.6 × 10(4) km(2) and fluctuated with no significant trend from 2001 to 2012. The mean biomass density was 505.4 g/m(2), with 62.6 g/m(2) in AGB and 442.8 g/m(2) in BGB, which generally decreased from northeast to southwest and exhibited a large spatial heterogeneity. The year-to-year AGB pattern was generally consistent with the inter-annual variation in the growing season precipitation (GSP), showing a robust positive correlation (R(2)=0.82, P<0.001), but an opposite coupled pattern was observed with the growing season temperature (GST) (R(2)=0.61, P=0.003). Climatic factors also affected the spatial distribution of AGB, which increased progressively with the GSP gradient (R(2)=0.76, P<0.0001) but decreased with an increasing GST (R(2)=0.70, P<0.0001). An improved moisture index that combined the effects of GST and GSP explained more variation in AGB than did precipitation alone (R(2)=0.81, P<0.0001). The relationship between AGB and GSP could be fit by a power function. This increasing slope of the GSP-AGB relationships along the GSP gradient may be partly explained by the GST-GSP spatial pattern in Xilingol. Our findings suggest that the relationships between climatic factors and AGB may be scale-dependent and that multi-scale studies and sufficient long-term field data are needed to examine the relationships between AGB and climatic factors.