Changes in individual plant traits and biomass allocation in alpine meadow with elevation variation on the Qinghai-Tibetan Plateau

Plant traits and individual plant biomass allocation of 57 perennial herbaceous species, belonging to three common functional groups (forbs, grasses and sedges) at subalpine (3700 m ASL), alpine (4300 m ASL) and subnival (>= 5000 m ASL) sites were examined to test the hypothesis that at high altitudes, plants reduce the proportion of aboveground parts and allocate more biomass to belowground parts, especially storage organs, as altitude increases, so as to geminate and resist environmental stress. However, results indicate that some divergence in biomass allocation exists among organs. With increasing altitude, the mean fractions of total biomass allocated to aboveground parts decreased. The mean fractions of total biomass allocation to storage organs at the subalpine site (7%+/- 2% S.E.) were distinct from those at the alpine (23%+/- 6%) and subnival (21%+/- 6%) sites, while the proportions of green leaves at all altitudes remained almost constant. At 4300 m and 5000 m, the mean fractions of flower stems decreased by 45% and 41%, respectively, while fine roots increased by 86% and 102%, respectively. Specific leaf areas and leaf areas of forbs and grasses deceased with rising elevation, while sedges showed opposite trends. For all three functional groups, leaf area ratio and leaf area root mass ratio decreased, while fine root biomass increased at higher altitudes. Biomass allocation patterns of alpine plants were characterized by a reduction in aboveground reproductive organs and enlargement of fine roots, while the proportion of leaves remained stable. It was beneficial for high altitude plants to compensate carbon gain and nutrient uptake under low temperature and limited nutrients by stabilizing biomass investment to photosynthetic structures and increasing the absorption surface area of fine roots. In contrast to forbs and grasses that had high mycorrhizal infection, sedges had higher single leaf area and more root fraction, especially fine roots.

Three-color white electroluminescence from a single polymer system with blue, green and red dopant units as individual emissive species and polyfluorene as individual polymer host

A white electroluminescent single polymer system with both high electroluminescence efficiency and excellent color rendering index (CRI) value is developed by covalently attaching blue, green, and red dopant units as individual light-emitting species to the side chain of polyfluorene as individual polymer host. A luminous efficiency of 8.6 cd A(-1), CIE coordinates of (0.33, 0.36) and CRI value of 88 was demonstrated with their single-layer devices.

Shell model study of single-particle and collective structure in neutron-rich Cr isotopes

The structure of neutron-rich Cr isotopes is systematically investigated by using the spherical shell model. The calculations reproduce well the known energy levels for the even-even Cr52-62 and odd-mass Cr53-59 nuclei, and predict a lowering of excitation energies around neutron number N = 40. The calculated B(E2; 2(1)(+) -> 0(1)(+)) systematics shows a pronounced collectivity around N = 40; a similar characteristic behavior has been suggested for Zn and Ge isotopes. Causes for the sudden drop of the 9/2(1)(+) energy in Cr-59 and the appearance of very low 0(2)(+) states around N = 40 are discussed. We also predict a new band with strong collectivity built on the 0(2)(+) state in the N = 40 isotope Cr-64.

High-spin states and collective band structures in the odd-odd Pm-140 nucleus

The high-spin states of Pm-140 have been investigated through the reaction Te-126(F-19, 5n) at a beam energy of 90 MeV. A previous level scheme based on the 8(-) isomer has been updated with spin up to 23 (h) over bar. A total of 22 new levels and 41 new transitions were identified. Six collective bands were observed. Five of them were expanded or re-constructed, and one of them was newly identified. The systematic signature splitting and inversion of the yrast pi h(11/2)circle times vh(11/2) band in Pr and Pm odd-odd isotopes has been discussed. Based on the systematic comparison, two Delta I = 2 bands were proposed as double-decoupled bands; other two bands with strong Delta I = 1 M1 transitions inside the bands were suggested as oblate bands with gamma similar to -60 degrees; another band with large signature splitting has been proposed with oblate-triaxial deformation with gamma similar to -90 degrees. The characteristics for these bands have been discussed.

MISCIBILITY OF POLY(EPICHLOROHYDRIN) WITH POLY(VINYL ACETATE) AND POLY(STYRENE-CO-ACRYLONITRILE)

The phase behaviours of poly(vinyl acetate) (PVAc) and poly(styrene-co-acrylonitrile)s (SAN) with poly(epichlorohydrin) (PECH) were examined using differential scanning calorimetry and an optical method using a hot plate. The PECH/PVAc blends showed LCST behaviour. The observed miscibility is thought to be a result of hydrogen-bonding interactions between the alpha-hydrogen atoms of PECH and the carbonyl groups of PVAc. Two SAN copolymers with an acrylonitrile (AN) content of 18 wt% (SAN18) and 25 wt% (SAN25), respectively, were also found to exhibit miscibility with PECH. No phase separation occurred by heating up to about 280-degrees-C, and the individual blend has a single, composition-dependent glass transition temperature. The formation of miscible PECH/SAN blends can be considered as a result of the intramolecular repulsion between styrene and AN units in SAN.