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To study the effects of source-sink ratio and nutrient supply on photosynthetic acclimation to CO(2) elevation, we subjected white birch seedlings to two levels of nutrient supply (high vs. low) and CO(2) concentrations (ambient vs. doubled [CO(2)]) for two months and then shaded the lower canopy on half of the seedlings to reduce source/sink ratio for an additional month. The CO(2) elevation significantly increased P(n) and IWUE at both nutrient levels but the increase was greater in the high than low nutrient treatment. The CO(2) elevation resulted in a down-regulation of V(cmax) in the low nutrient treatment but up-regulation of J(max), TPU, [Formula: see text] and J(c) in the high nutrient after 3 months of treatment. Both the CO(2) elevation and high nutrient supply increased the partition of total electron transport to carboxylation at the expense of oxidation. The seedlings responded to the shading of the lower canopy by reducing biomass allocation to roots rather than making physiological adjustments to unshaded leaves in the upper canopy. Our results suggest that the direction of photosynthetic acclimation to CO(2) elevation in white birch was nutrient-dependent and an increase in sink strength could reduce the feedback inhibition of photosynthesis., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

To study the effects of elevated CO2 concentration ([CO2]) on relationships between nitrogen (N) nutrition and foliar gas exchange parameters, white birch (Betula papyrifera Marsh.) seedlings were exposed to one of five N-supply regimes (10, 80, 150, 220, 290 mg N l(-1)) in either ambient [CO2] (360 micromol mol(-1)) or elevated [CO2] (720 micromol mol(-1)) in environment-controlled greenhouses. Foliar gas exchange and chlorophyll fluorescence were measured after 60 and 80 days of treatment. Photosynthesis showed a substantial down-regulation (up to 57%) in response to elevated [CO2] and the magnitude of the down-regulation generally decreased exponentially with increasing leaf N concentration. When measured at the growth [CO2], elevated [CO2] increased the overall rate of photosynthesis (P(n)) and instantaneous water-use efficiency (IWUE) by up to 69 and 236%, respectively, but decreased transpiration (E) and stomatal conductance (g(s)) in all N treatments. However, the degree of stimulation of photosynthesis by elevated [CO2] decreased as photosynthetic down-regulation increased from 60 days to 80 days of treatment. Elevated [CO2] significantly increased total photosynthetic electron transport in all N treatments at 60 days of treatment, but the effect was insignificant after 80 days of treatment. Both P(n) and IWUE generally increased with increasing leaf N concentration except at very high leaf N concentrations, where both P(n) and IWUE declined. The relationships of P(n) and IWUE with leaf N concentration were modeled with both a linear regression and a second-order polynomial function. Elevated [CO2] significantly and substantially increased the slope of the linear regression for IWUE, but had no significant effect on the slope for P(n). The optimal leaf N concentration for P(n) and IWUE derived from the polynomial function did not differ between the CO2 treatments when leaf N was expressed on a leaf area basis. However, the mass-based optimal leaf N concentration for P(n) was much lower in seedlings in elevated [CO2] than in ambient [CO2] (31.88 versus 37.00 mg g(-1)). Elevated [CO2] generally decreased mass-based leaf N concentration but had no significant effect on area-based leaf N concentration; however, maximum N concentration per unit leaf area was greater in elevated [CO2] than in ambient [CO2] (1.913 versus 1.547 g N m(-2)).

To investigate the interactive effects of atmospheric carbon dioxide concentration ([CO(2)]) and nutrition on photosynthesis and its acclimation to elevated [CO(2)], a two-way factorial experiment was carried out with two nutritional regimes (high- and low-nitrogen (N), phosphorus (P) and potassium (K)) and two CO(2) concentrations (360 and 720 ppm) with white birch seedlings (Betula papyrifera Marsh.) grown for four months in environment-controlled greenhouses. Elevated [CO(2)] enhanced maximal carboxylation rate (V(cmax)), photosynthetically active radiation-saturated electron transport rate (J(max)), actual photochemical efficiency of photosystem II (PSII) in the light (DeltaF/F(m)') and photosynthetic linear electron transport to carboxylation (J(c)) after 2.5 months of treatment, and it increased net photosynthetic rate (A(n)), photosynthetic water-use efficiency (WUE), photosynthetic nitrogen-use efficiency (NUE) and photosynthetic phosphorus-use efficiency (PUE) after 2.5 and 3.5 months of treatment, but it reduced stomatal conductance (g(s)), transpiration rate (E) and the fraction of total photosynthetic linear electron transport partitioned to oxygenation (J(o)/J(T)) after 2.5 and 3.5 months of treatment. Low nutrient availability decreased A(n), WUE, V(cmax), J(max), triose phosphate utilization (TPU), (/F(m)' - F)//F(m)' and J(c), but increased J(o)/J(T) and NUE. Generally, V(cmax) was more sensitive to nutrient availability than J(max). There were significant interactive effects of [CO(2)] and nutrition over time, e.g., the positive effects of high nutrition on A(n), V(cmax), J(max), DeltaF/F(m)' and J(c) were significantly greater in elevated [CO(2)] than in ambient [CO(2)]. In contrast, the interactive effect of [CO(2)] and nutrition on NUE was significant after 2.5 months of treatment, but not after 3.5 months. High nutrient availability generally increased PUE after 3.5 months of treatment. There was evidence for photosynthetic up-regulation in response to elevated [CO(2)], particularly in seedlings receiving high nutrition. Photosynthetic depression in response to low nutrient availability was attributed to biochemical limitation (or increased mesophyll resistance) rather than stomatal limitation. Elevated [CO(2)] reduced leaf N concentration, particularly in seedlings receiving low nutrition, but had no significant effect on leaf P or K concentration. High nutrient availability generally increased area-based leaf N, P and K concentrations, but had negligible effects on K after 2.5 months of treatment.

One-year-old jack pine (Pinus banksiana Lamb.) and current-year white birch (Betula papyrifera Marsh.) seedlings were grown in ambient (360 ppm) or twice ambient (720 ppm) atmospheric CO2 concentration ([CO2]) and at three soil temperatures (Tsoil = 7, 17 and 27 degrees C initially, increased to 10, 20 and 30 degrees C two months later, respectively) in a greenhouse for 4 months. In situ foliar gas exchange, in vivo carboxylation characteristics and chlorophyll fluorescence were measured after 2.5 and 4 months of treatment. Low Tsoil suppressed net photosynthetic rate (Pn), stomatal conductance (g(s)) and transpiration rate (E) in jack pine in both CO2 treatments and g(s) and E in white birch in ambient [CO2], but enhanced instantaneous water-use efficiency (IWUE) in both species after 2.5 months of treatment. Treatment effects on g(s) and E remained significant throughout the 4-month study. Low Tsoil reduced maximal carboxylation rate (Vcmax) and PAR-saturated electron transport rate (Jmax) in jack pine in elevated [CO2] after 2.5 months of treatment, but not after 4 months of treatment. Low Tsoil increased actual photochemical efficiency of photosystem II (PSII) in the light (DeltaF/Fm') in jack pine, but decreased DeltaF/Fm' in white birch after 4 months of treatment. In response to low Tsoil, photosynthetic linear electron transport to carboxylation (Jc) decreased in jack pine after 2.5 months and in white birch after 4 months of treatment. Low Tsoil increased the ratio of the photosynthetic linear electron transport to oxygenation (Jo) to the total photosynthetic linear electron transport rate through PSII (Jo/J(T)) in both species after 2.5 months of treatment, but the effects became statistically insignificant in white birch after 4 months of treatment. High Tsoil decreased foliar N concentration in white birch. Elevated [CO2] increased Pn, IWUE and Jc but decreased Jo/J(T) in both species at both measurement times except Jc in white birch after 2.5 months of treatment. Elevated [CO2] also decreased g(s) and E in white birch at high Tsoil, Vcmax in both species and triose phosphate utilization in white birch at low Tsoil after 4 months of treatment, and DeltaF/Fm' in white birch after 2.5 months of treatment. Elevated [CO2] also increased foliar N concentration in both species. Low Tsoil caused no permanent damage to PSII in either species, but jack pine responded and acclimated to low Tsoil more quickly than white birch. Photosynthetic down-regulation and a decrease in photosynthetic electron transport to photorespiration occurred in both species in response to elevated [CO2].

Epitaxial heterostructures, in particular those 2D vertical heterostructures with close face-to-face contact, are appealing candidates for photocatalytic CO 2 reduction. Usually, precise control of the growth rate and a seed nanosheet having a small lattice mismatch with the overlayer is essential for the realization of epitaxial growth. Here we present a CO 2 -initiated solution-phase epitaxial growth strategy to directly fabricate 2D facet-coupled vertical heterostructures without a seed-layer assistant, in which supercritical CO 2 liquid can not only manipulate the nucleation and growth of BiOIO 3 to match with the epitaxial growth of the Bi 2 O 2 CO 3 layer, but also provide better wetting conditions to minimize the interfacial energy, thus facilitating the 2D layer-by-layer growth. The obtained heterostructures exhibit the highest CO 2 -to-CO conversion rate of 224.71 µmol g−1 h−1 in pure water. These findings open up a new platform for highly controlled epitaxial growth of heterostructures. [Display omitted] • A CO 2 -initiated solution-phase epitaxial growth strategy was proposed. • Supercritical CO 2 can manipulate the nucleation and growth of BiOIO 3. • A 2D facet-coupled vertical heterostructures for CO 2 photoreduction are created. [ABSTRACT FROM AUTHOR]

CO 2 capture, storage and utilization (CCSU) is the most promising strategy for ameliorating the ever-increasing atmospheric CO 2 concentrations problem. The development of advanced porous solid adsorbents for efficient CCSU is a burgeoning interest in materials science. Currently, porous carbon-based adsorbents face the major challenge of balancing the structural features of porosity and surface chemistry for CCSU in a durable and scalable material. To this end, we designed hierarchically porous carbons with tailorable porosity and adjustable surface chemistry, and clarify the influence of porosity and surface chemistry on CO 2 capture. Meanwhile, the systematic study revealed the synergetic effect of microporosity of less than 10 Å and surface chemistry on CO 2 capture, and the synergistic effect mechanism of various surface groups on CO 2 capture property was also ascertained in detail. Porosity was found to be the determinant role on CO 2 capture, in particular the microporosity of < 10 Å and ultramicroporosity of < 7.0 Å. While, surface chemistry played a significant role on the improvement of CO 2 capture, especially the CO 2 /N 2 selectivity at higher temperature. Importantly, this work provided an instructive guideline for rational design of high-efficient porous carbon CO 2 adsorbents with a balanced porosity and surface chemistry property. ● Hierarchically porous carbon with tailorable porosity and surface chemistry was obtained. ● The effect of porosity and surface chemistry on CO 2 capture was clarified. ● The synergistic effect mechanism of various surface groups was ascertained. ● An instructive guideline for rational design of porous carbon adsorbents was provided. [ABSTRACT FROM AUTHOR]

To study the effects of elevated CO2 concentration ([CO2]) on relationships between nitrogen (N) nutrition and foliar gas exchange parameters, white birch (Betula papyrifera Marsh.) seedlings were exposed to one of five N-supply regimes (10, 80, 150, 220, 290 mg Nl-1) in either ambient [CO2] (360 µmol mol-1) or elevated [CO2] (720 µmol mol-1) in environment-controlled greenhouses. Foliar gas exchange and chlorophyll fluorescence were measured after 60 and 80 days of treatment. Photosynthesis showed a substantial down-regulation (up to 57%) in response to elevated [CO2] and the magnitude of the down-regulation generally decreased exponentially with increasing leaf N concentration. When measured at the growth [CO2], elevated [CO2] increased the overall rate of photosynthesis (Pn) and instantaneous water-use efficiency (IWUE) by up to 69 and 236%, respectively, but decreased transpiration (E) and stomatal conductance (gs) in all N treatments. However, the degree of stimulation of photosynthesis by elevated [CO2] decreased as photosynthetic down-regulation increased from 60 days to 80 days of treatment. Elevated [CO2] significantly increased total photosynthetic electron transport in all N treatments at 60 days of treatment, but the effect was insignificant after 80 days of treatment. Both Pn and IWUE generally increased with increasing leaf N concentration except at very high leaf N concentrations, where both Pn and IWUE declined. The relationships of Pn and IWUE with leaf N concentration were modeled with both a linear regression and a second-order polynomial function. Elevated [CO2] significantly and substantially increased the slope of the linear regression for IWUE, but had no significant effect on the slope for Pn. The optimal leaf N concentration for Pn and IWUE derived from the polynomial function did not differ between the CO2 treatments when leaf N was expressed on a leaf area basis. However, the mass-based optimal leaf N concentration for Pn was much lower in seedlings in elevated [CO2] than in ambient [CO2] (31.88 versus 37.00 mg g-1). Elevated [CO2] generally decreased mass-based leaf N concentration but had no significant effect on area-based leaf N concentration; however, maximum N concentration per unit leaf area was greater in elevated [CO2] than in ambient [CO2] (1.913 versus 1.547 g N m-2). [ABSTRACT FROM AUTHOR]