Invasive reptilian predators can have substantial impacts on native species and ecosystems. Tegu lizards are widely distributed in South America east of the Andes, and are popular in the ...international live animal trade. Two species are established in Florida (U.S.A.) - Salvator merianae (Argentine black and white tegu) and Tupinambis teguixin sensu lato (gold tegu) - and a third has been recorded there- S. rufescens (red tegu). We built species distribution models (SDMs) using 5 approaches (logistic regression, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy) based on data from the native ranges. We then projected these models to North America to develop hypotheses for potential tegu distributions. Our results suggest that much of the southern United States and northern México probably contains suitable habitat for one or more of these tegu species. Salvator rufescens had higher habitat suitability in semi-arid areas, whereas S. merianae and T. teguixin had higher habitat suitability in more mesic areas. We propose that Florida is not the only state where these taxa could become established, and that early detection and rapid response programs targeting tegu lizards in potentially suitable habitat elsewhere in North America could help prevent establishment and abate negative impacts on native ecosystems.
The co-conversion of CO2 and CH4 into oxygenates with nonthermal plasma is attracting considerable interest, principally because this approach can overcome thermodynamic limitations and enables ...operation under mild conditions. However, plasma must be coupled with appropriate catalysts in order to achieve satisfactory oxygenate selectivities. In this article, the mechanisms underlying plasma-catalytic CO2 + CH4 conversion to three different types of oxygenates (CH3OH, HCHO, and CH3COOH) are discussed along the scales of reaction time (ns to ms) and dimension (nm to mm). Particular emphasis is given to the synergy between plasma-phase and surface reactions. In addition, typical materials (both catalytic and noncatalytic) and experimental setups that can affect the selectivities of oxygenated products are also highlighted.
The production of chemicals and fuels via chemical reduction of CO2 by green H2 represents a promising means of mitigating CO2 emissions. The heterogeneous catalytic reaction of CO2 and H2 under ...atmospheric pressure primarily produces CO and CH4, while CH3OH and C2+ hydrocarbons are obtained at high pressure. Improving the catalytic selectivity improves the energy efficiency for a given yield and greatly reduces the downstream separation costs. In this work, we review the recent progress in tuning the selectivity of CO2 hydrogenation over heterogeneous catalysts at atmospheric pressure. We describe fundamental insights into the relationships among the electronic properties of active metals, the binding strengths of key intermediates, and the CO2 hydrogenation selectivity. The manipulation of the electronic properties, and consequently the product selectivity, can be achieved mainly by controlling the particle size, bimetallic effects, and strong metal–support interactions. Finally, we discuss challenges and opportunities for the rational design of CO2 hydrogenation catalysts with high activity and desired selectivity.
Ammonia synthesis by plasma catalysis has emerged as an alternative process for decoupling nitrogen fixation from fossil fuels. Plasma activation can potentially circumvent the limitations of ...conventional thermocatalytic ammonia synthesis; however, the contribution of different reaction mechanisms to the production of ammonia at the catalyst surface remains unclear. Here, we identify the reaction intermediates adsorbed on γ-Al2O3-supported Ni and Fe catalysts during plasma-activated ammonia synthesis under various temperatures and reactor configurations using FTIR spectroscopy, steady-state flow reactor experiments, and computational kinetic modeling. Ammonia yield can be influenced by plasma-derived intermediates and their interactions with catalyst surfaces, which lead to different reaction pathways: Ni/γ-Al2O3 enhances plasma-promoted NH3 production and favors surface-adsorbed NH x species, while Fe/γ-Al2O3 shows the presence of N2H y and a lower overall concentration of N-containing adsorbates. Plasma–catalyst interactions are probed to reveal that elevated temperature and plasma irradiation of the surfaces promote NH3 desorption. The direct evidence of catalytic surface reactions occurring during a plasma-activated process provides mechanistic insight into plasma-activated ammonia synthesis.
Removal of organic micropollutants from water through advanced oxidation processes (AOPs) is hampered by the excessive input of energy and/or chemicals as well as the large amounts of residuals ...resulting from incomplete mineralization. Herein, we report a new water purification paradigm, the direct oxidative transfer process (DOTP), which enables complete, highly efficient decontamination at very low dosage of oxidants. DOTP differs fundamentally from AOPs and adsorption in its pollutant removal behavior and mechanisms. In DOTP, the nanocatalyst can interact with persulfate to activate the pollutants by lowering their reductive potential energy, which triggers a non-decomposing oxidative transfer of pollutants from the bulk solution to the nanocatalyst surface. By leveraging the activation, stabilization, and accumulation functions of the heterogeneous catalyst, the DOTP can occur spontaneously on the nanocatalyst surface to enable complete removal of pollutants. The process is found to occur for diverse pollutants, oxidants, and nanocatalysts, including various low-cost catalysts. Significantly, DOTP requires no external energy input, has low oxidant consumption, produces no residual byproducts, and performs robustly in real environmental matrices. These favorable features render DOTP an extremely promising nanotechnology platform for water purification.
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•Loops and channels are both promising dynamic engineering targets for altered enzymatic properties.•The relevance of loop dynamics in engineering studies highlights to address this ...property consciously.•Inspiring studies on channel engineering motivate to expand this approach to more enzymes.•The integrative use of simulation and experiment for prediction and elucidation is crucial to unlock the potential of loop and channel engineering.
Enzymes are nature’s powerful catalytic proteins to perform reactions with often outstanding activity, selectivity and specificity. Moreover, the access to non-natural functions of biocatalysts can be facilitated by enzyme engineering. While rational approaches are often focused on an enzyme’s active site, from random directed evolution we know that further functional hotspots must exist beyond the active site. Addressing flexible structural elements of these biocatalysts like loops and channels in enzyme engineering has the potential to fill this knowledge gap. The structural dynamics of enzyme catalysts are vital to promote their remarkable functions. This influences for example the access, recognition and orientation of substrates. Herein, we review recent examples of loop and channel engineering and classify them according to their use of simulation methodologies, predictions prior to engineering, the engineering methodologies themselves and discoveries found after the engineering. Thereby we highlight current possibilities and make suggestions to further unlock the potential of this yet underexplored strategy.
The implementation and popularity of next generation sequencing (NGS) has led to the development of various rapid whole mitochondrial genome sequencing techniques. We summarise an efficient and ...cost-effective NGS approach for mitochondrial genomic DNA in humans using the Ion Torrent platform, and further discuss our bioinformatics pipeline for streamlined variant calling. Ion 316 chips were utilised with the Ion Torrent semi-conductor platform Personal Genome Machine (PGM) to perform tandem sequencing of mitochondrial genomes from the core pedigree (n = 315) of the Norfolk Island Health Study. Key improvements from commercial methods focus on the initial PCR step, which currently requires extensive optimisation to ensure the accurate and reproducible elongation of each section of the complete mitochondrial genome. Dual-platform barcodes were incorporated into our protocol thereby extending its potential application onto Illumina-based systems. Our bioinformatics pipeline consists of a modified version of GATK best practices tailored for mitochondrial genomic data. When compared with current commercial methods, our method, termed high throughput mitochondrial genome sequencing (HTMGS), allows high multiplexing of samples and the use of alternate library preparation reagents at a lower cost per sample (~1.7 times) when compared to current commercial methodologies. Our HTMGS methodology also provides robust mitochondrial sequencing data (>450X average coverage) that can be applied and modified to suit various study designs. On average, we were able to identify ~30 variants per sample with 572 variants observed across 315 samples. We have developed a high throughput sequencing and analysis method targeting complete mitochondrial genomes; with the potential to be platform agnostic with analysis options that adhere to current best practices.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Many drugs and other xenobiotics may reach systemic concentrations where they interact not only with the proteins that are their therapeutic targets but also modify the physicochemical properties of ...the cell membrane, which may lead to altered function of many transmembrane proteins beyond the intended targets. These changes in bilayer properties may contribute to nonspecific, promiscuous changes in membrane protein and cell function because membrane proteins are energetically coupled to their host lipid bilayer. It is thus important, for both pharmaceutical and biophysical reasons, to understand the bilayer-modifying effect of amphiphiles (including therapeutic agents). Here we use atomic force microscopy topography imaging and nanomechanical mapping to monitor the effect of statins, a family of hypolipidemic drugs, on synthetic lipid membranes. Our results reveal that statins alter the nanomechanical stability of the bilayers and increase their elastic moduli depending on the lipid bilayer order. Our results also suggest that statins increase bilayer heterogeneity, which may indicate that statins form nanometer-sized aggregates in the membrane. This is further evidence that changes in bilayer nanoscale mechanical properties may be a signature of lipid bilayer-mediated effects of amphiphilic drugs.
Municipalities are turning to ecological restoration of urban forests as a measure to imporve air quality, ameliorate urban heat island effects, improve storm water infiltration, and provide other ...social and ecological benefits. However, community dynamics following urban forest restoration treatments are poorly documented. This study examines the long-term effects of ecological restoration undertaken in New York City, New York, USA, to restore native forest in urban park natural areas invaded by woody non-native plants that are regional problems. In 2009 and 2010, we sampled vegetation in 30 invaded sites in three large public parks that were restored 1988–1993, and 30 sites in three large parks that were similarly invaded but had not been restored. Data from these matched plots reveal that the restoration treatment achieved its central goals. After 15–20 years, invasive species removal followed by native tree planting resulted in persistent structural and compositional shifts, significantly lower invasive species abundance, a more complex forest structure, and greater native tree recruitment. Together, these findings indicate that successional trajectories of vegetation dynamics have diverged between restored forests and invaded forests that were not restored. In addition, the data suggest that future composition of these urban forest patches will be novel assemblages. Restored and untreated sites shared a suite of shade-intolerant, quickly-growing tree species that colonize disturbed sites, indicating that restoration treatments created sites hospitable for germination and growth of species adapted to high light conditions and disturbed soils. These findings yield an urban perspective on the use of succession theory in ecological restoration. Models of ecological restoratin developed in more pristine environments must be modified for use in cities. By anticipating both urban disturbances and ecological succession, management of urban forest patches can be adjusted to better predict and direct long-term outcomes. An urban approach to ecological restoration must use realistic, flexible targets to perserve and enhance urban biodiversity for both short-term benefits and long-term sustainability.
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