Effects of cadmium on chlorophyll content, photochemical efficiency, and photosynthetic intensity of Canna indica Linn.

The effects of cadmium (Cd2+) on growth status, chlorophyll (Chl) content, photochemical efficiency, and photosynthetic intensity were studied on Canna indica Linn. Plant specimens that were produced from a constructed wetland and precultivated hydroponically in 20 L of 1/10 Hoagland solution under greenhouse conditions for I week were exposed to cadmium in concentrations of 0, 0.4, 0.8, 1.6 and 3.2 mg L- Cd2+, respectively. The results show that leaves were injured in the Cd2+ solution by the third day of exposure and the injury became more serious with an increase in the applied heavy metal. Under 3.2 mg L-1 Cd2+ treatment, growth retardation, the decrease of chlorophyll content from 0.70 to 0.43 mg g(-1) FW, and a decrease in Chl a/b ratio from 2.0 to 1.2 were observed. Chl a was more sensitive than Chl b to Cd2+ stress. The decrease was the same with photochemical efficiency. Photosynthetic intensity decreased by 13.3% from 1.5X10(4) mumol m(-2)s(-1) CO2 in control to 1.3x10(4) mumol m(2)s(-1) CO2 in the treatment of 3.2 mg L-1. Because Canna species are used in heavy metal phytoremediation, these results show that C. indica can tolerate 0.4 to 0.8 mg L-1 Cd2+. Therefore, it is a potential species for phytoremediation of cadmium with some limitations only at higher concentrations.

High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre

A high efficiency and broad bandwidth grating coupler between a silicon-on-insulator (SOI) nanophotonic waveguide and fibre is designed and fabricated. Coupling efficiencies of 46% and 25% at a wavelength of 1.55 mu m are achieved by simulation and experiment, respectively. An optical 3 dB bandwidth of 45 nm from 1530 nm to 1575 nm is also obtained in experiment. Numerical calculation shows that a tolerance to fabrication error of 10 nm in etch depth is achievable. The measurement results indicate that the alignment error of +/-2 mu m results in less than 1 dB additional coupling loss.

Quantum efficiency and temperature coefficients of GaInP/GaAs dual-junction solar cell

GaInP/GaAs dual-junction solar cell with a conversion efficiency of 25.2% has been fabricated using metalorganic chemical vapor deposition (MOCVD) technique. Quantum efficiencies of the solar cell were measured within a temperature range from 25 to 160A degrees C. The results indicate that the quantum efficiencies of the subcells increase slightly with the increasing temperature. And red-shift phenomena of absorption limit for all subcells are observed by increasing the cell's work temperature, which are consistent with the viewpoint of energy gap narrowing effect. The short-circuit current density temperature coefficients dJ (sc)/dT of GaInP subcell and GaAs subcell are determined to be 8.9 and 7.4 mu A/cm(2)/A degrees C from the quantum efficiency data, respectively. And the open-circuit cell voltage temperature coefficients dV (oc)/dT calculated based on a theoretical equation are -2.4 mV/A degrees C and -2.1 mV/A degrees C for GaInP subcell and GaAs subcell.

A 20.1 W Solid-State Laser Pumped by 887 nm with High Efficiency and TEM00 Mode

High efficiency, TEM00 mode, high repetition rate laser pumped by 887 nm is reported. 20.1 W output laser emitting at 1064 nm is achieved in a 0.3 at % Nd-doped Nd:YVO4, which absorbs pumping light of 30.7 W at 887 nm. The opto-optic efficiency and the slope efficiency are 65.5 and 88.5%, respectively. The stable Q-switching operation worked well at 100 kHz and the beam quality is near diffraction-limit with M-2 factor measured as M-2 approximate to 1.2. And the pulse waveform is analyzed in this paper.

Radiation-use efficiency and the harvest index of winter wheat at different nitrogen levels and their relationships to canopy spectral reflectance

Radiation-use efficiency (RUE, g/MJ) and the harvest index (HI, unitless) are two helpful characteristics in interpreting crop response to environmental and climatic changes. They are also increasingly important for accurate crop yield simulation, but they are affected by various environmental factors. In this study, the RUE and HI of winter wheat and their relationships to canopy spectral reflectance were investigated based on the massive field measurements of five nitrogen (N) treatments. Crop production can be separated into light interception and RUE. The results indicated that during a long period of slow growth from emergence to regreening, the effect of N on crop production mainly showed up in an increased light interception by the canopy. During the period of rapid growth from regreening to maturity, it was present in both light interception and RUE. The temporal variations of RUEAPAR (aboveground biomass produced per unit of photosynthetically active radiation absorbed by the canopy) during the period from regreening to maturity had different patterns corresponding to the N deficiency, N adequacy and N-excess conditions. Moreover, significant relationships were found between the RUEAPAR and the accumulative normalised difference vegetation index (NDVI) in the integrated season (R-2 = 0.68), between the HI and the accumulative NDVI after anthesis (R-2 = 0.89), and between the RUEgrain (ratio of grain yield to the total amount of photosynthetically active radiation absorbed by the canopy) and the accumulative NDVI of the whole season (R-2 = 0.89) and that after anthesis (R-2 = 0.94). It suggested that canopy spectral reflectance has the potential to reveal the spatial information of the RUEAPAR, HI and RUEgrain. It is hoped that this information will be useful in improving the accuracy of crop yield simulation in large areas.

The role of molybdenum oxide as anode interfacial modification in the improvement of efficiency and stability in organic light-emitting diodes

It has been experimentally found that molybdenum oxide (MoO3) as the interfacial modification layer on indium-tin-oxide (ITO) in organic light-emitting diodes (OLEDs) significantly improves the efficiency and lifetime. In this paper, the role of MoO3 and MoO3 doped N,N '-di(naphthalene-1-yl)-N,N '-diphenyl-benzidine (NPB) as the interface modification layer on ITO in improvement of the efficiency and stability of OLEDs is investigated in detail by atomic force microscopy (AFM), polarized optical microscopy, transmission spectra, ultraviolet photoemission spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS).

Combined Effects of Hot Curing Conditions and Reaction Heat on Rubber Vulcanization Efficiency and Vulcanizate Uniformity

A mathematical model of the chemical kinetics of silicone rubber Vulcanization is developed, with the thermal effects being computed using the increment method, and the hot Vulcanization process estimated with the finite element method. The results show that the reaction heat of rubber vulcanization is important for energy saving, and that a proper curing medium temperature is important when considering both vulcanization efficiency and vulcanizate uniformity. The results also indicate that increases in the forced convective heat transfer coefficient have no significant effect above a certain level. The validity of the numerical model is indirectly proven by comparison with existing data.

Fluorene-Based Copolymers Containing Dinaphtho-s-indacene as New Building Blocks for High-Efficiency and Color-Stable Blue LEDs

By incorporating a new building block, 7,7,15,15-tetraoctyldinaphtho-s-indacene (NSI), into the backbone of poly(9,9-dioctylfluorene) (PFO), a novel series of blue light-emitting copolymers (PFO-NSI) have been developed. The insertion of the NSI unit into the PFO backbone leads to the increase of local effective conjugation length, to form low-energy fluorene-NSI-fluorene (FNF) segments that serve as exciton trapping sites, to which the energy transfers from the high-energy PFO segments. This causes these copolymers to show red-shifted emissions compared with PFO, with a high efficiency and good color stability and purity. The best device performance with a luminance efficiency of 3.43 cd . A(-1), a maximum brightness of 6 539 cd . m(-2) and CIE coordinates of (0.152, 0.164) was achieved.

High efficiency and stable dye-sensitized solar cells with an organic chromophore featuring a binary pi-conjugated spacer

We employed a binary spacer of orderly conjugated 3,4-ethyldioxythiophene and thienothiophene to construct a wide-spectral response organic chromophore for dye-sensitized solar cells, exhibiting a high power conversion efficiency of 9.8% measured under irradiation of 100 mW cm(-2) air mass 1.5 global (AM1.5G) sunlight and an excellent stability.

High-efficiency and low-cost hybrid nanomaterial as enhancing electrocatalyst: Spongelike AWN core/shell nanomaterial with hollow cavity

A high-efficiency and low-cost spongelike Au/Pt core/shell electrocatalyst with hollow cavity has been facilely obtained via a simple two-step wet chemical process. Hollow gold nanospheres were first synthesized via a modified galvanic replacement reaction between Co nanoparticles in situ produced and HAUCl(4). The as-prepared gold hollow spheres were employed as seeds to further grow spongelike Pt shell. It is found that the surface of this hybrid nanomaterial owns many Pt nanospikes, which form a spongelike nanostructure. All experimental data including scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis-near-infrared spectroscopy have been employed to characterize the obtained Au/Pt hybrid nanomaterial. The rapid development of fuel cell has inspired us to investigate the electrocatalytic properties for dioxygen and methanol of this novel hybrid nanomaterial. Spongelike hybrid nanomaterial mentioned here exhibits much higher catalytic activity for dioxygen reduction and methanol oxidation than the common Pt electrode.

White electroluminescence from a single polymer system: Improved performance by means of enhanced efficiency and red-shifted luminescence of the blue-light-emitting species

High-efficiency white electrolurninescence from a single polymer is achieved by enhancing the electroluminescence efficiency and effecting a red-shift in the emission spectrum of the blue emissive species. A single-layer device of the resultant polymer exhibits a higher luminous efficiency than the nonmodified species (12.8 cd A(-1), see figure) and an external quantum efficiency of 5.4 % with CIE coordinates of (0.31,0.36), exemplifying the success of the reported methodology.