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In this paper, a pot experiment was conducted to simulate different degrees of saline-alkali stress to explore the response mechanism of Pennisetum giganteum Z. X. Lin to salt stress concerning its growth and physiological characteristics. The results showed that: (1) the growth of plant height decreased obviously with the increase of salt solution concentration; (2) with the increase of concentration, MDA content accumulated intermittently, P. giganteum reduced oxidative damage and maintained normal plant physiological metabolism through the complementary action of antioxidant enzymes SOD and CAT; (3) when the concentration of mixed salt solution was low, all osmotic regulatory substances accumulated slowly, and with the continuous increase of concentration, free proline content increased rapidly, which played a leading role in the process of plant osmotic regulation to ensure its physiological activities; (4) under mixed saline-alkali stress, the roots and stems of P. giganteum absorbed most of the Na+ , and transported K+ to the leaves at the same time. [ABSTRACT FROM AUTHOR]

Secondary organic aerosols (SOA) derived from isoprene, pinene and caryophyllene were determined for PM10 and size-segregated (9-stage) aerosols collected at the summit (2060 m, a.s.l.) of Mt. Hua, central China during the summer of 2009. Concentrations of estimated isoprene, α-/β-pinene and β-caryophyllene derived SOC are 81± 53, 29 ± 14 and 98 ± 53 ng m-3, accounting for 2.7± 1.0%, 0.8 ± 0.2% and 2.1 ± 1.0% of OC, respectively. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature (R=0.57-0.90). However, a decreasing trend of BSOA concentration with an increase in relative humidity (RH) was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. Size distribution measurement showed that most of the determined isoprene derived SOA may form in aerosol phase and enriched in the fine mode (<2.1μm). 3-Hydroxyglutaric acid, 3-methyl-1,2,3-butanetricarboxylic acid and β-caryophyllinic acid are only presented in fine particles. However, cis-pinonic acid presents a large peak in the coarse mode (>2.1 μm) due to its highly volatile nature. [ABSTRACT FROM AUTHOR]

We report a mode expansion transfer matrix method to describe the nanowaveguide-based strongly coupling waveguide directional couplers, including slab nanowaveguide coupler, silicon-on-insulator (SOI) nanowires coupler, and silica nanofibers coupler. We propose a general mode expansion description of coupler without the assumption of weakly guiding. For the slab nanowaveguide case, all the coefficients inside those matrices could be identified theoretically using mode expansion method. The analytical results of coupler show excellent agreement with the simulation results obtained by the finite-difference time-domain method. For the nanofiber coupler, with the mode profiles obtained numerically using finite element method, similar matrix equation could be used for the guideline of nanofiber coupler design, which is the key issue of coupler-based nanofiber devices and SOI nanowires devices. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1123–1129, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25093 [ABSTRACT FROM AUTHOR]