Edwards et al. (2022, https://doi.org/10.1029/2021pa004386) take tree ring samples from Scots pine trees in Sämtland, Sweden, and analyze them to reconstruct the summer temperatures for 1783. The ...maximum latewood density data for 1783 are low, suggesting cooler temperatures. The authors conclude that anatomical anomalies in their samples resulted from acidic damage caused by the Laki haze, a dry and sulfuric smelling fog emitted by the Laki fissure in Iceland during its eruption, which lasted from 8 June 1783 to 7 February 1784. This finding resolves a long‐standing discrepancy between historical documents that indicate an unusually warm summer in 1783 and temperature reconstructions based on tree rings that often suggested a cooler summer. The paper by Edwards et al. (2022, https://doi.org/10.1029/2021pa004386) thereby shows the potential of interdisciplinary collaborations: Only by studying historical records does it becomes apparent that the summer was not cold but warm. Historical records indicate further that the Laki haze also affected the vegetation in other parts of Europe, such as England, the Low Countries, and Germany. Further study of tree rings to reconstruct the temperature of other regions is desirable.
Plain Language Summary
Edwards et al. (2022, https://doi.org/10.1029/2021pa004386) collected tree samples from Sämtland in Sweden to study their rings, specifically those rings pertaining to their maximum latewood density. The analysis, focusing on the period from 1768 to 1798, has shown that the anatomy of the latewood of these trees was anomalous for the year 1783. The authors propose that this was caused by the acidic, dry fog produced by the Laki eruption in Iceland. This eruption released very large volumes of sulfur dioxide and other volcanic gases into the atmosphere, which traveled widely across the northern hemisphere. Because the acidic fog changed the anatomy of the trees, their rings were no longer suitable to read the temperature for the summer of 1783 accurately. These tree rings seemed to indicate that it was cold, but historical records strongly suggest that the summer was, in fact, very warm. Natural scientists and historians can only reach such conclusions when they work together.
Key Points
The findings by Edwards et al. (2022) resolve a discrepancy between historical documents and tree ring‐based temperature reconstructions
Without an analysis of the historical records that show a warm summer, this discrepancy would not have become apparent
Historical records reveal other areas (Low Countries, Germany) also experienced vegetation damage and have potential for further studies
The catalyzed semihydrogenation of dibromomethane (CH2Br2) to methyl bromide (CH3Br) is a key step in the bromine-mediated upgradation of methane. This study presents a cutting-edge strategy ...combining density functional theory (DFT), catalytic tests complemented with the extensive characterization of a wide range of metal catalysts (Fe, Co, Ni, Cu, Ru, Rh, Ag, Ir, and Pt), and statistical tools for a computer-assisted investigation of this reaction. The steady-state catalytic tests identified four classes of materials comprising (i) poorly active (<8%) Fe/SiO2, Co/SiO2, Cu/SiO2, and Ag/SiO2; (ii) Rh/SiO2 and Ni/SiO2, which exhibit intermediate CH3Br selectivity (<60%); (iii) Ir/SiO2 and Pt/SiO2, which display great propensity to CH4 (>50%); and (iv) Ru/SiO2, which exhibits the highest selectivity to CH3Br (up to 96%). In-depth characterization of representative catalysts in fresh and used forms was done by X-ray diffraction, inductively coupled plasma optical emission spectroscopy, N2 sorption, temperature-programmed reduction, Raman spectroscopy, electron microscopy, and X-ray photoelectron spectroscopy. The dimensionality reduction performed on the 272 DFT intermediate adsorption energies using principal component analysis identified two descriptors that, when employed together with the experimental data in a random forest regressor, enabled the understanding of activity and selectivity trends by connecting them to the energy intervals of the descriptors. In addition, a representative analytic model was found using the Bayesian inference. These findings illustrate the exciting opportunities presented by integrated experimental/computational screening and set the fundamental basis for the accelerated discovery of superior hydrodebromination catalysts and beyond.
Bark and leaves of Ailanthus altissima (Mill.) Swingle are widely used in European folk medicine to treat intestinal worm infections. The study aimed to rationalize a potential anthelmintic effect of ...A. altissima extract against the model organism Caenorhabditis elegans. A methanol-water (7:3, v/v) extract of the primary stem bark was tested on L4 larvae of C. elegans for induction of mortality and influence on reproduction. Bioactivity-guided fractionation was performed by chromatography on MCI-gel, preparative HPLC on RP18 stationary phase and fast-centrifugal-partition-chromatography. Structural elucidation of isolated quassinoids was performed by NMR and HR-ESI-MS. The sterilizing effect on C. elegans was investigated by light microscopy and atomic force microscopy of ultra-sections. Different GFP-tagged reporter strains were used to identify involved signaling pathways. A. altissima extract (1 mg/mL) irreversibly inhibited the reproduction of C. elegans L4 larvae. This effect was dependent on the larval stage since L3 larvae and adults were less affected. Bioactivity-guided fractionation revealed the quassinoid ailanthone 1 as the major active compound (IC50 2.47 μM). The extract caused severe damages to germ cells and rachis, which led to none or only poorly developed oocytes. These damages led to activation of the transcription factor DAF-16, which plays a major role in the nematode's response to stress. A regulation via the respective DAF-2/insulin-like signaling pathway was not observed. The current findings support the traditional use of A. altissma in phytotherapy to treat helminth infections and provide a base for standardization of the herbal material.
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In the northern Red Sea, the nestling and facultatively boring pectinid bivalve Pedum spondyloideum lives embedded in various scleractinian host corals of seven families, including the previously ...unrecorded hosts Astreopora, Leptastrea and Hydnophora. Pedum density varied according to host species, locality and depth. The bivalve-occupied coral surface (OCS) was measured on samples and from close-up photos taken in the field. Based on the 9x6 cm photo frames, Pedum density ranged from 1.9-18.6/100 cm super(2). In 14 Montipora, apparently the favourite host genus, mean density was 6.5/100 cm super(2) and mean OCS 3.4 %, but maximum OCS amounted to 12.5 %. In 19x13 cm frames, Pedum density ranged from 0.4-10.7/100 cm super(2). The maximum density occurred again in Montipora, followed by Porites 6.7/100 cm super(2) and Cyphastrea (6.0/100 cm super(2)). The OCS ranged from 0.2-7.0 %. The latter was found in Goniastrea, and 6.6 % OCS in Montipora. The mean density of Pedum in 13 Montipora was 3.6/100 cm super(2) and mean OCS 2.2 %. Heavy infestation does not appear to impact the corals, except in growth form. Shell size and dwelling volume are highly correlated. From the opening length on the coral surface, the expected volume can be calculated using the regression y=0.2127 x super(2.7447). A high Pedum density indicates a southerly reef site or near-shore locality with ample suspended nutrients in the water. Successions of Pedum generations in the same host demonstrate that corals usually outlive their inhabitants by many years. The embedded traces are less distinct than in the coral-associated mytilid Lithophaga. Compared with the latter, Pedum dwellings have a less regular shape and a much wider opening. Coral overgrowth partly fills and camouflages dwellings. Although no fossil record is known, Pedum traces have a fossilisation potential.
Hundreds of natural recruits were observed on coral slabs exposed for five to six months at Uraba Island (Taboga Islands, Eastern Pacific) in the course of experiments with chemically boring ...bivalves. Based on the size range of the specimens, the recruitment was a very fast phenomenon where many settled probably within days, many more during the following weeks. Recruits of the most common species, the mytilid Lithophaga (Leiosolenus) aristata (Dillwyn, 1817), reached up to 16.3 mm in length after 165 days during 'winter' experiments. Densities of up to 5 borehole orifices per cm super(2) were found. Differences in recruitment on experimentally exposed substrates and possible reasons for the fast and intense settlement of boring bivalves at Uraba Island are discussed.Original Abstract: Centinaia di colonizzazioni sono state osservate su lastre ottenute da colonie di coralli esposte per un periodo compreso tra 5 e 6 mesi nelle acque dell'Isola di Uraba, presso le Isole Taboga (Pacifico orientale), nel corso di esperimenti su bivalvi perforanti con modalita chimica. Sulla base delle dimensioni degli esemplari, la colonizzazione risulta essere stata molto veloce, con molte larve che si sono impiantate entro pochi giorni, e molte di piu durante le settimane successive. La specie piu comune, il mitilide Lithophaga (Leiosolenus) aristata (Dillwyn, 1817), ha raggiunto una dimensione massima di 16.3 mm di lunghezza dopo 165 giorni, durante la fase sperimentale 'invernale'. Per i bivalvi perforanti, e stata riscontrata una densita massima pari a 5 perforazioni per cm super(2). Vengono discusse le differenze nella colonizzazione di substrati esposti sperimentalmente e i possibili motivi della veloce ed intensa colonizzazione da parte di bivalvi perforanti nelle acque dell'Isola di Uraba.
Pacific specimens of Lithophaga and its subgenus Leiosolenus, collected during recent French expeditions to New Caledonia, Vanuatu, the Philippines and French Polynesia, were determined and ...described, including two new species, Lithophaga (Leiosolenus) paraplumula n. sp. and Lithophaga (Leiosolenus) subattenuata n. sp. From the twenty species, three belong to Lithophaga s.s. and seventeen to the subgenus Leiosolenus. In order to help identification of the two new species and some others, selected specimens are figured in left lateral, right lateral and dorsal view. A taxonomic key is provided for determination.Original Abstract: Il presente lavoro presenta lo studio di esemplari Lithophaga e del suo sottogenere Leiosolenus, raccolti in Nuova Caledonia, Vanuatu, Filippine e nella Polinesia Francese, in occasione di spedizioni francesi. Tutti gli esemplari vengono identificati a livello specifico, e descritti. Vengono introdotte due nuove specie: Lithophaga (Leiosolenus) paraplumula n. sp. e Lithophaga (Leiosolenus) subattenuata n. sp. Su venti specie esaminate, tre appartengono a Lithophaga s.s. e diciassette al sottogenere Leiosolenus. Al fine di favorire l'identificazione delle due nuove specie e di altre, vengono fornite le illustrazione di alcuni esemplari in vista laterale sinistra, laterale destra e dorsale. Inoltre, viene proposta una chiave di identificazione.
