scholarly journals Changes in species abundance after seven years of elevated atmospheric CO2 and warming in a Subarctic birch forest understorey, as modified by rodent and moth outbreaks

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4843 ◽  
Author(s):  
Brita M. Svensson ◽  
Bengt Å. Carlsson ◽  
Jerry M. Melillo
Keyword(s):  
Plant Community ◽  
Elevated Temperatures ◽  
Global Climate ◽  
Species Abundance ◽  
Additional Treatment ◽  
Permanent Plots ◽  
Epirrita Autumnata ◽  
Ambient Conditions ◽  
Clethrionomys Rufocanus ◽  
Long Term Study

A seven-year long, two-factorial experiment using elevated temperatures (5 °C) and CO2 (concentration doubled compared to ambient conditions) designed to test the effects of global climate change on plant community composition was set up in a Subarctic ecosystem in northernmost Sweden. Using point-frequency analyses in permanent plots, an increased abundance of the deciduous Vaccinium myrtillus, the evergreens V. vitis-idaea and Empetrum nigrum ssp. hermaphroditum and the grass Avenella flexuosa was found in plots with elevated temperatures. We also observed a possibly transient community shift in the warmed plots, from the vegetation being dominated by the deciduous V. myrtillus to the evergreen V. vitis-idaea. This happened as a combined effect of V. myrtillus being heavily grazed during two events of herbivore attack—one vole outbreak (Clethrionomys rufocanus) followed by a more severe moth (Epirrita autumnata) outbreak that lasted for two growing seasons—producing a window of opportunity for V. vitis-idaea to utilize the extra light available as the abundance of V. myrtillus decreased, while at the same time benefitting from the increased growth in the warmed plots. Even though the effect of the herbivore attacks did not differ between treatments they may have obscured any additional treatment effects. This long-term study highlights that also the effects of stochastic herbivory events need to be accounted for when predicting future plant community changes.

scholarly journals Shifts in soil and plant functional diversity along an altitudinal gradient in the French Alps

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Alexia Stokes ◽  
Guillermo Angeles ◽  
Fabien Anthelme ◽  
Eduardo Aranda-Delgado ◽  
Isabelle Barois ◽  
...  
Keyword(s):  
Plant Community ◽  
Functional Diversity ◽  
Plant Communities ◽  
Species Abundance ◽  
Chemical Properties ◽  
Water Infiltration ◽  
Temperate Climate ◽  
Biophysical Properties ◽  
Tropical Zone ◽  
Soil Microbial

Abstract Objectives Altitude integrates changes in environmental conditions that determine shifts in vegetation, including temperature, precipitation, solar radiation and edaphogenetic processes. In turn, vegetation alters soil biophysical properties through litter input, root growth, microbial and macrofaunal interactions. The belowground traits of plant communities modify soil processes in different ways, but it is not known how root traits influence soil biota at the community level. We collected data to investigate how elevation affects belowground community traits and soil microbial and faunal communities. This dataset comprises data from a temperate climate in France and a twin study was performed in a tropical zone in Mexico. Data description The paper describes soil physical and chemical properties, climatic variables, plant community composition and species abundance, plant community traits, soil microbial functional diversity and macrofaunal abundance and diversity. Data are provided for six elevations (1400–2400 m) ranging from montane forest to alpine prairie. We focused on soil biophysical properties beneath three dominant plant species that structure local vegetation. These data are useful for understanding how shifts in vegetation communities affect belowground processes, such as water infiltration, soil aggregation and carbon storage. Data will also help researchers understand how plant communities adjust to a changing climate/environment.

scholarly journals Recent advances in the electrochemical construction of heterocycles

2014 ◽  
Vol 10 ◽  
pp. 2858-2873 ◽  
Author(s):  
Robert Francke
Keyword(s):  
Heterocyclic Compounds ◽  
Elevated Temperatures ◽  
Ring Formation ◽  
Environmentally Benign ◽  
Heterocyclic Chemistry ◽  
Ambient Conditions ◽  
Recent Developments ◽  
Strong Acids ◽  
Selection Of ◽  
Made In

Due to the fact that the major portion of pharmaceuticals and agrochemicals contains heterocyclic units and since the overall number of commercially used heterocyclic compounds is steadily growing, heterocyclic chemistry remains in the focus of the synthetic community. Enormous efforts have been made in the last decades in order to render the production of such compounds more selective and efficient. However, most of the conventional methods for the construction of heterocyclic cores still involve the use of strong acids or bases, the operation at elevated temperatures and/or the use of expensive catalysts and reagents. In this regard, electrosynthesis can provide a milder and more environmentally benign alternative. In fact, numerous examples for the electrochemical construction of heterocycles have been reported in recent years. These cases demonstrate that ring formation can be achieved efficiently under ambient conditions without the use of additional reagents. In order to account for the recent developments in this field, a selection of representative reactions is presented and discussed in this review.

scholarly journals Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
High Performance ◽  
Density Functional ◽  
High Stability ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Proton Exchange ◽  
Efficient Production ◽  
Ambient Conditions

Proton-exchange membrane water electrolysers provide many advantages for the energy-efficient production of H<sub>2</sub>, but the current technology relies on high loadings of expensive iridium at the anodes, which are often unstable in operation. To address this, the present work scrutinises the properties of antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as flat thin films by a solution-based method for the oxygen evolution reaction in 0.5 M H<sub>2</sub>SO<sub>4</sub>. Among the non-noble-metal catalysts, only cobalt-antimony and manganese-antimony oxides demonstrate high stability and reasonable activity under ambient conditions, but slowly lose activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm<sup>-2</sup> at 24 ± 2 and 80 °C, respectively, and remaining remarkably stable during one-week tests at 80 °C. The <i>S</i>-number for this catalyst is higher than that for the high-performance benchmark Ir-based systems. Density functional theory analysis and physical characterisation reveal that this high stability is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by antimony, and can arise from two distinct structural scenarios: either formation of an antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites.

The Vibrational Spectra of NH4VO3 at Elevated Temperatures and Pressures

1987 ◽  
Vol 42 (7) ◽  
pp. 843-852 ◽  
Author(s):  
A . M. Heyns ◽  
M. W. Venter ◽  
K.-J. Range
Keyword(s):  
Hydrogen Bonds ◽  
Temperature Dependence ◽  
Vibrational Spectra ◽  
Elevated Temperatures ◽  
Structural Data ◽  
Volume Effect ◽  
Ambient Conditions ◽  
Hydrogen Bond Interactions ◽  
Diamond Anvil ◽  
Pressure Changes

Abstract Results obtained from the vibrational spectra of NH4VO3 and its deuterated analogues show that at least two types of hydrogen bond interactions can be identified at am bient conditions. In accordance with the structural data on NH4VO3 (F. C. Hawthorne and C. Calvo, J. Solid State Chem. 22, 157 (1977)) these interactions are assigned to normal, strong hydrogen bonds and weaker bifurcated ones, respectively. The temperature dependence of some of the N -H bands indicates that the normal hydrogen bonds decrease in strength with increasing temperatures, while the bifurcated ones tend to increase in strength. The NH4+ ions do not show fluxional behaviour at ambient conditions and even the bifurcated hydrogen bonds are of the type that is dominated by acceptor strength of the anions and not by a volume effect. The Ram an active NH4+ vibrations are very weak compared to the V - O modes and could not all be observed in the highpressure diamond anvil cell. The temperature dependence of the V - O Ram an active modes suggests that changes in the crystals of NH4VO3 brought about by the application of heat mainly involve the O -V -O angles, while pressure changes are mostly accommodated by changes in the V -O bridging bonds and O -V -O bridging angles.

scholarly journals Anaerobic Methane Oxidation in High-Arctic Alaskan Peatlands as a Significant Control on Net CH4 Fluxes

Soil Systems ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 7 ◽  
Author(s):  
Kimberley Miller ◽  
Chun-Ta Lai ◽  
Randy Dahlgren ◽  
David Lipson
Keyword(s):  
Global Climate ◽  
Average Rate ◽  
High Arctic ◽  
Reaction Rate Constant ◽  
Anaerobic Oxidation Of Methane ◽  
Ambient Conditions ◽  
Oxidation Of Methane ◽  
Ch4 Production ◽  
Shallow Soils

Terrestrial consumption of the potent greenhouse gas methane (CH4) is a critical aspect of the future climate, as CH4 concentrations in the atmosphere are projected to play an increasingly important role in global climate forcing. Anaerobic oxidation of methane (AOM) has only recently been considered a relevant control on methane fluxes from terrestrial systems. We performed in vitro anoxic incubations of intact peat from Utqiaġvik (Barrow), Alaska using stable isotope tracers. Our results showed an average potential AOM rate of 15.0 nmol cm3 h−1, surpassing the average rate of gross CH4 production (6.0 nmol cm3 h−1). AOM and CH4 production rates were positively correlated. While CH4 production was insensitive to additions of Fe(III), there was a depth:Fe(III) interaction in the kinetic reaction rate constant for AOM, suggestive of stimulation by Fe(III), particularly in shallow soils (<10 cm). We estimate AOM would consume 25–34% of CH4 produced under ambient conditions. Soil genetic surveys showed phylogenetic links between soil microbes and known anaerobic methanotrophs in ANME groups 2 and 3. These results suggest a prevalent role of AOM to net CH4 fluxes from Arctic peatland ecosystems, and a probable link with Fe(III)-reduction.

scholarly journals Shape-changing tensegrity-membrane building skin

2020 ◽  
Vol 310 ◽  
pp. 00046
Author(s):  
Lenka Kabošová ◽  
Eva Kormaníková ◽  
Stanislav Kmeť ◽  
Dušan Katunský
Keyword(s):  
Design Method ◽  
Global Climate ◽  
Weather Conditions ◽  
Building Envelope ◽  
Digital Design ◽  
Design Stage ◽  
Design Tools ◽  
Ambient Conditions ◽  
Weather Extremes ◽  
The Impact

Building skins are persistently exposed to changes in the weather, including the cases of weather extremes, increasing in frequency due to global climate change. As a consequence of the advancements of digital design tools, the integration of the weather conditions into the design process is much smoother. The impact of the ambient conditions on buildings and their structures can be digitally analyzed as early as in the conceptual design stage. These new design tools stimulate original ideas for shape-changing building skins, actively reacting to the dynamic weather conditions. In the paper, a digital design method is introduced, leading towards the design of a building skin, able of the passive shape adaptation when subjected to the wind. The designed building skin consists of a tensegrity structure where the tensioned elements are substituted by a tensile membrane, creating a self-equilibrated building skin element. In the previous research, a small prototype of this wind-adaptive element was created. The computer simulations are employed to predict the adaptive behavior of a bigger, full-scale building skin element. The before-mentioned building envelope becomes an active player in its surrounding environment, passively reacting to the wind in real-time, thanks to the geometric and material properties. Due to the local shape changes caused by the wind force, the wind can be perceived unconventionally through the adaptive building structure.

scholarly journals The Algal Symbiont Modifies the Transcriptome of the Scleractinian Coral Euphyllia paradivisa During Heat Stress

2019 ◽  
Vol 7 (8) ◽  
pp. 256 ◽  
Author(s):  
Dalit ◽  
Keren ◽  
Eviatar ◽  
Hiba ◽  
Gal ◽  
...  
Keyword(s):  
Heat Stress ◽  
Differentially Expressed Genes ◽  
Elevated Temperatures ◽  
Negative Impact ◽  
Global Climate ◽  
Differentially Expressed ◽  
Heat Stress Response ◽  
Stress Genes ◽  
Mutualistic Symbiosis ◽  
Algal Symbiont

The profound mutualistic symbiosis between corals and their endosymbiotic counterparts, Symbiodiniaceae algae, has been threatened by the increase in seawater temperatures, leading to breakdown of the symbiotic relationship—coral bleaching. To characterize the heat-stress response of the holobiont, we generated vital apo-symbiotic Euphyllia paradivisa corals that lacked the endosymbiotic algae. Using RNA sequencing, we analyzed the gene expression of these apo-symbionts vs. symbiotic ones, to test the effect of the algal presence on the tolerance of the coral. We utilized literature-derived lists of “symbiosis differentially expressed genes” and “coral heat-stress genes” in order to compare between the treatments. The symbiotic and apo-symbiotic samples were segregated into two separate groups with several different enriched gene ontologies. Our findings suggest that the presence of endosymbionts has a greater negative impact on the host than the environmental temperature conditions experienced by the holobiont. The peak of the stress reaction was identified as 28 °C, with the highest number of differentially expressed genes. We suggest that the algal symbionts increase coral holobiont susceptibility to elevated temperatures. Currently, we can only speculate whether coral species, such as E. paradivisa, with the plasticity to also flourish as apo-symbionts, may have a greater chance to withstand the upcoming global climate change challenge.

Continuous hydrothermal synthesis and crystallization of magnetic oxide nanoparticles

2002 ◽  
Vol 17 (9) ◽  
pp. 2410-2416 ◽  
Author(s):  
Linda J. Cote ◽  
Amyn S. Teja ◽  
Angus P. Wilkinson ◽  
Z. John Zhang
Keyword(s):  
Hydrothermal Synthesis ◽  
Elevated Temperatures ◽  
Metal Salt ◽  
Oxide Nanoparticles ◽  
Precipitation Reaction ◽  
Ambient Conditions ◽  
Magnetic Oxide ◽  
Synthesis Of Nanoparticles ◽  
Uniform Particles ◽  
Metal Salt Solution

The continuous hydrothermal synthesis of nanoparticles of two metal oxides (α–Fe2O3 and Co3O4) is described. Two variations of the technique were investigated, involving the precipitation reaction between a metal salt solution and a hydroxide solution at ambient conditions and at elevated temperatures. Elevated temperatures resulted in more uniform particles of α–Fe2O3 and Co3O4, although the actual sizes of the particles were apparently unaffected by the temperature. This behavior was attributed to the species present in solution and the solubilities of the cation(s), both of which were calculated via a thermodynamic model for the systems under study.

scholarly journals Thermal stability of retained austenite in bainitic steel: an  in situ study

2011 ◽  
Vol 467 (2135) ◽  
pp. 3141-3156 ◽  
Author(s):  
A. Saha Podder ◽  
I. Lonardelli ◽  
A. Molinari ◽  
H. K. D. H. Bhadeshia
Keyword(s):  
Martensitic Transformation ◽  
Retained Austenite ◽  
Elevated Temperatures ◽  
Bainitic Ferrite ◽  
Ambient Conditions ◽  
Two Phase ◽  
Tempering Temperature ◽  
Thermal Stability Of ◽  
Lower Carbon

The tempering of two-phase mixtures of bainitic ferrite and carbon-enriched retained austenite has been investigated in an effort to separate the reactions that occur at elevated temperatures from any transformation during cooling to ambient conditions. It is demonstrated using synchrotron X-radiation measurements that the residue of austenite left at the tempering temperature partly decomposes by martensitic transformation when the sample is cooled. It is well established in the published literature that films of retained austenite are better able to resist stress or strain-induced martensitic transformation than any coarser particles of austenite. In contrast, the coarser austenite is more resistant to the precipitation of cementite during tempering than the film form because of its lower carbon concentration.

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