The potential for dramatic increases in bioproductivity in algal photobioreactors relative to current biomass approaches,
e.g., for converting sunlight into biofuels, by an unorthodox integration of photonics and biotechnologies is described. The
key to greater biomass yields—projected as high as 100 g dry weight m−2 h−1—is a pronounced heightening of algal flux tolerance, achieved by tailoring the photonic temporal, spectral and intensity
characteristics with pulsed light-emitting diodes. Such tailored photonic input is applied in concert with thin-channel ultradense
culture photobioreactors with flow patterns that produce rapid light/dark algae exposure cycles. The artificial-light scheme
is globally feasible only with electricity generated from renewables. Recent advances in ultra-efficient concentrator photovoltaics,
as well as high-performance light-emitting diodes, create a practical reality for converting sunlight into pulsed red light
and delivering it to indoor photobioreactors, with characteristic pulse times and intensities optimally suited to the rate-limiting
dark reactions of photosynthesis. Cellular engineering built upon recent progress in modifying algal chlorophyll antenna size,
in combination with metabolic engineering, could further enhance bioproductivity. The proposed strategy requires no major
advances for implementation and adopts existing technologies.
Revision submitted to Applied Microbiology and Biotechnology on 25 June 2007. 相似文献
Little is known about the combined impacts of future CO2 and temperature increases on the growth and physiology of marine picocyanobacteria. We incubated Synechococcus and Prochlorococcus under present‐day (380 ppm) or predicted year‐2100 CO2 levels (750 ppm), and under normal versus elevated temperatures (+4°C) in semicontinuous cultures. Increased temperature stimulated the cell division rates of Synechococcus but not Prochlorococcus. Doubled CO2 combined with elevated temperature increased maximum chl a–normalized photosynthetic rates of Synechococcus four times relative to controls. Temperature also altered other photosynthetic parameters (α, Φmax, Ek, and ) in Synechococcus, but these changes were not observed for Prochlorococcus. Both increased CO2 and temperature raised the phycobilin and chl a content of Synechococcus, while only elevated temperature increased divinyl chl a in Prochlorococcus. Cellular carbon (C) and nitrogen (N) quotas, but not phosphorus (P) quotas, increased with elevated CO2 in Synechococcus, leading to ~20% higher C:P and N:P ratios. In contrast, Prochlorococcus elemental composition remained unaffected by CO2, but cell volume and elemental quotas doubled with increasing temperature while maintaining constant stoichiometry. Synechococcus showed a much greater response to CO2 and temperature increases for most parameters measured, compared with Prochlorococcus. Our results suggest that global change could influence the dominance of Synechococcus and Prochlorococcus ecotypes, with likely effects on oligotrophic food‐web structure. However, individual picocyanobacteria strains may respond quite differently to future CO2 and temperature increases, and caution is needed when generalizing their responses to global change in the ocean. 相似文献
A connection between vitamin D deficiency and severe health problems including various types of cancer has been demonstrated. We have shown that patients that have to protect themselves against solar UV radiation for medical reasons, including patients with xeroderma pigmentosum (XP), basal cell nevus syndrome (BCNS), lupus erythematodes (LE) or transplant recipients, are at risk to develop vitamin D deficiency. We conclude that 25-hydroxyvitamin D serum levels as a measure of vitamin D status have to be analyzed in patients that have to protect themselves against solar UV radiation for medical reasons. Suboptimal vitamin D status has to be substituted (e.g. via oral treatment) to protect against serious vitamin D deficiency-related health problems without increasing the risk to develop solar UV-induced skin cancer. Our finding that protection against solar UV radiation causes vitamin D deficiency underlines the need for re-defining dermatological recommendations for solar UV protection in skin cancer prevention programs. 相似文献
In late summer 2004 stem discs were collected from about 40 juniper trees (Juniperus Siberica Burgsd) growing at the remote central part of Kola Peninsula behind the polar circle at the northern timberline. Up to now these juniper trees are oldest ones found at Kola Peninsula. Data processing was difficult due to extremely small tree rings as well as the occurrence of missing and false rings. However, finally it was possible to build up a 676-year long chronology and retrieve information on the past climatic variations at Kola Peninsula that could partly be linked to extraterrestrial factors such as changes in solar activity and galactic cosmic ray activity. It was obtained that:
(1) There is a rather good agreement between long-term climatic variation in Europe and at Kola Peninsula.
(2) The minima of solar activity Sporer (1416–1534 AD), Maunder (1645–1715 AD) and Dalton (1801–1816 AD) were accompanied by temperature decreases. Cooling during the end of the Wolf minimum (until 1350) is reflected in the juniper tree-ring series from Kola Peninsula whereas it is not reflected in the European temperature reconstructions.
(3) Some recent decreases in solar activity around 1900 and 1960 are linked to phases of reduced growth in juniper.
(4) The juniper chronologies from Kola Peninsula do not indicate a temperature rise at the end of the XX century.
(5) MTM spectral and wavelet analysis of juniper tree-ring records showed:
(a) more pronounced 22- and 80–100-year periodicities;
(b) the main cycle of solar activity, the 11-year Schwabe cycle, was not present;
(c) 20–22-year periodicity was not significant throughout the entire ca.700-year period, but during certain time intervals: 1328–1550, 1710–1800, 1985 to present.
Keywords: Juniperus Siberica Burgsd; 676-year chronology; Kola Peninsula; Solar cycles 相似文献
Because seedlings and mature trees do not necessarily respond similarly to O(3) stress, it is critically important that exposure systems be developed that allow exposure of seedlings through to mature trees. Here we describe three different O(3) Free-Air Exposure Systems that have been used successfully for exposure at all growth stages. These systems of spatially uniform O(3) release have been shown to provide reliable O(3) exposure with minimal, if any, impact on the microclimate. This methodology offers a welcome alternative to chamber studies which had severe space constraints precluding stand or community-level studies and substantial chamber effects on the microclimate and, hence physiological tree performance. 相似文献
Pathogenicity of nematophagous fungus Paecilomyces lilacinus (Thom) Samson in control of the most destructive greenhouse pests such as: greenhouse whitefly, Trialeurodes vaporariorum, glasshouse red spider mite, Tetranychus urticae, the cotton aphid, Aphis gossypii and western flower thrips, Frankliniella occidentalis was examined in laboratory and pot experiments. The fungus showed the greatest efficacy in controlling winged and wingless
forms of the cotton aphid. The cotton aphid’s population was almost totally eliminated. In controlling the greenhouse whitefly,
P. lilacinus was most successful when applied against nymphal growth stages (L3-L4). Control of the western flower thrips was most efficient against prepupal and pupal stages when the fungus was applied as
a water spore suspension to the soil. When the fungus was applied at temperatures below 10 °C, it was able to reduce a glasshouse
red spider mite population by 60%. 相似文献
Temperature in agricultural production has a direct impact on the growth of crops. The emergence of greenhouses has improved the impact of the original unpredictable changes in temperature, but the temperature modeling of greenhouses is still the main direction at present. Neural network modeling relies on sufficient actual data
to model greenhouses, but there is a widening gap in the application of different neural networks. This paper
proposes a greenhouse temperature prediction model based on wavelet neural network with genetic algorithm
(GA-WNN). With the simple network structure and the nonlinear adaptability of the wavelet basis function,
wavelet neural network (WNN) improved model training speed and accuracy of prediction results compared with
back propagation neural networks (BPNN), which was conducive to the prediction and control of short-term
greenhouse temperature fluctuations. At the same time, the genetic algorithm (GA) was introduced to globally
optimize the initial weights of the original model, which improved the insensitivity of the model to the initial
weights and thresholds, and improved the training speed and stability of the model. Finally, simulation results
for the greenhouse showed that the model training speed, prediction results accuracy and model stability of
the GA-WNN in the greenhouse were improved in comparison to results obtained by the WNN and BPNN
in the greenhouse. 相似文献