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Plants and cyanobacteria use the chlorophylls embedded in their photosystems to absorb photons and perform charge separation, the first step of converting solar energy to chemical energy. While oxygenic photosynthesis is primarily based on chlorophyll a photochemistry, which is powered by red light, a few cyanobacterial species can harness less energetic photons when growing in far-red light. Acclimatization to far-red light involves the incorporation of a small number of molecules of red-shifted chlorophyll f in the photosystems, whereas the most abundant pigment remains chlorophyll a. Due to its different energetics, chlorophyll f is expected to alter the excited-state dynamics of the photosynthetic units and, ultimately, their performances. Here we combined time-resolved fluorescence measurements on intact cells and isolated complexes to show that chlorophyll f insertion slows down the overall energy trapping in both photosystems. While this marginally affects the efficiency of photosystem I, it substantially decreases that of photosystem II. Nevertheless, we show that despite the lower energy output, the insertion of red-shifted chlorophylls in the photosystems remains advantageous in environments that are enriched in far-red light and therefore represents a viable strategy for extending the photosynthetically active spectrum in other organisms, including plants. However, careful design of the new photosynthetic units will be required to preserve their efficiency.

In this paper we present a methodology to measure the energy consumption of software. The methodology is based on detailed monitoring of power usage of hardware components. We explain our lab setup after which we apply the methodology to different pieces of DNS resolver software. Through this case study we demonstrate some of the uses of our methodology, as it can be used to determine which software performs the tasks at hand in the most energy efficient way, what the influence of software configuration can be, etcetera.

The influence of two strains of Trichoderma (T. harzianum strain T22 and T. atroviride strain P1) on the growth of lettuce plants (Lactuca sativa L.) irrigated with As-contaminated water, and their effect on the uptake and accumulation of the contaminant in the plant roots and leaves, were studied. Accumulation of this non-essential element occurred mainly into the root system and reduced both biomass development and net photosynthesis rate (while altering the plant P status). Plant growth-promoting fungi (PGPF) of both Trichoderma species alleviated, at least in part, the phytotoxicity of As, essentially by decreasing its accumulation in the tissues and enhancing plant growth, P status and net photosynthesis rate. Our results indicate that inoculation of lettuce with selected Trichoderma strains may be helpful, beside the classical biocontrol application, in alleviating abiotic stresses such as that caused by irrigation with As-contaminated water, and in reducing the concentration of this metalloid in the edible part of the plant.

AbstractAimBats are promising candidates for studying morphometric responses to anthropogenic climate or land‐use changes. We assessed whether the cranial size of a common bat (Pipistrellus kuhlii) had changed between 1875 and 2007. We formulated the following hypotheses: (1) if heat loss is an important reaction to climate change, body size will have decreased in response to the increased temperatures, because small bats have a larger surface‐to‐volume ratio and dissipate heat more effectively; (2) if water loss is the main driver, body size will have increased in response to the temperature increase, because larger bats will lose water more slowly through a reduced surface‐to‐volume ratio; (3) the energetic benefits provided by urbanization (food concentration at street lamps, warmer maternity roosts in buildings) will lead to a general body size increase in P. kuhlii; and (4) because street lamps impair moth antipredatory manoeuvres, cranial size may have selectively increased as an adaptive response to handle larger prey (moths) in artificially illuminated sites. Ours is the first study to assess temporal trends in bat body size over more than a century and to relate them to urbanization.LocationMainland Italy.MethodsWe used traditional morphometrics to compare seven variables of skull size in 117 museum specimens (75 female, 42 male).ResultsCranial size increased after 1950, but this change was not paralleled by an increase in body size, measured as forearm length. This selective increase matched a rapid increase in electric public illumination in Italy.Main conclusionsStreet lights are crucial foraging sites for P. kuhlii. The directional change that we found in cranial size might represent microevolutionary adaptive tracking of a sudden shift in food size, making more profitable prey available.

Using natural photosynthesis as a model, bio-inspired constructs for fuel generation from sunlight are being developed. Here we report the synthesis and time-resolved spectroscopic analysis of a molecular triad in which a porphyrin electron donor is covalently linked to both a cyanoporphyrin electron acceptor and a benzimidazole-phenol model for the TyrZ-D1His190 pair of PSII. A dual-laser setup enabled us to record the ultrafast kinetics and long-living species in a single experiment. From this data, the photophysical relaxation pathways were elucidated for the triad and reference compounds. For the triad, quenching of the cyanoporphyrin singlet excited state lifetime was interpreted as photoinduced electron transfer from the porphyrin to the excited cyanoporphyrin. In contrast to a previous study of a related molecule, we were unable to observe subsequent formation of a long-lived charge separated state involving the benzimidazole-phenol moiety. The lack of detection of a long-lived charge separated state is attributed to a change in energetic landscape for charge separation/recombination due to small differences in structure and solvation of the new triad.

The process of photosynthesis is initiated by the capture of sunlight by a network of light-absorbing molecules (chromophores), which are also responsible for the subsequent funneling of the excitation energy to the reaction centers. Through evolution, genetic drift, and speciation, photosynthetic organisms have discovered many solutions for light harvesting. In this review, we describe the underlying photophysical principles by which this energy is absorbed, as well as the mechanisms of electronic excitation energy transfer (EET). First, optical properties of the individual pigment chromophores present in light-harvesting antenna complexes are introduced, and then we examine the collective behavior of pigment-pigment and pigment-protein interactions. The description of energy transfer, in particular multichromophoric antenna structures, is shown to vary depending on the spatial and energetic landscape, which dictates the relative coupling strength between constituent pigment molecules. In the latter half of the article, we focus on the light-harvesting complexes of purple bacteria as a model to illustrate the present understanding of the synergetic effects leading to EET optimization of light-harvesting antenna systems while exploring the structure and function of the integral chromophores. We end this review with a brief overview of the energy-transfer dynamics and pathways in the light-harvesting antennas of various photosynthetic organisms.

------------------------------------------------------------------------------------------------------------------------------------------- This version has been superseded. The latest version is at https://doi.org/10.5281/zenodo.5517550 ------------------------------------------------------------------------------------------------------------------------------------------- Eddy covariance flux tower datasets of all Urban-PLUMBER sites, associated with the manuscript: "Harmonized, gap-filled dataset from 20 urban flux tower sites" Use of any data must give credit through citation of the above manuscript and other sources as appropriate. We recommend data users consult with site contributing authors and/or the coordination team in the project planning stage. Relevant contacts are included in timeseries metadata. For site information and timeseries plots see https://urban-plumber.github.io/sites. For processing code see https://github.com/matlipson/urban-plumber_pipeline. Within each site folder: - `index.html`: A summary page with site characteristics and timeseries plots. - `SITENAME_sitedata_vX.csv`: comma seperated file for numerical site characteristics e.g. location, surface cover fraction etc. - `timeseries/` (following files available as netCDF and txt) - `SITENAME_raw_observations_vX`: site observed timeseries before project-wide quality control. - `SITENAME_clean_observations_vX`: site observed timeseries after project-wide quality control. - `SITENAME_metforcing_vX`: site observed timeseries after project-wide quality control and gap filling. - `SITENAME_era5_corrected_vX`: site ERA5 surface data (1990-2020) with bias corrections as applied in the final dataset. - `log_processing_SITENAME_vX.txt`: a log of the print statements through running the create_dataset_SITENAME scripts. Authors Mathew Lipson, Sue Grimmond, Martin Best, Andreas Christen, Andrew Coutts, Ben Crawford, Bert Heusinkveld, Erik Velasco, Helen Claire Ward, Hirofumi Sugawara, Je-Woo Hong, Jinkyu Hong, Jonathan Evans, Joseph McFadden, Keunmin Lee, Krzysztof Fortuniak, Leena Järvi, Matthias Roth, Nektarios Chrysoulakis, Nigel Tapper, Oliver Michels, Simone Kotthaus, Stevan Earl, Sungsoo Jo, Valéry Masson, Winston Chow, Wlodzimierz Pawlak, Yeon-Hee Kim. Corresponding author: Mathew Lipson <m.lipson@unsw.edu.au>

Hybrid life cycle assessment (LCA), through combining input-output (IO) models and process-based LCA for a complete system boundary, is widely recognized as a more accurate approach than process-based LCA with an incomplete system boundary. Without a complete process model for verification, however, the performance of hybrid LCA remains unclear. Here, using a counterexample we show that hybrid LCA does not necessarily provide more accurate results than process-based LCA, simply because the aggregation of heterogeneous processes in IO models may introduce more errors. In so doing, we prove that only when IO-based LCA and process-based LCA have the same level of detail would they yield the same results. Whether hybrid LCA provides more accurate estimates depends on whether the IO model introduced serves as an adequate proxy for the missing products as opposed to if they were estimated by a complete process model. The use of a highly-aggregated IO model runs the risk of overestimation, and could result in a larger relative error than the truncation error resulting from an incomplete process model. Our study seeks to provide a balanced view of hybrid LCA, and our findings offer important insights for future hybrid LCA studies to improve the accuracy and realm of applicability of the approach.