Autochthonous microorganisms a consortium of arbuscular-mycorrhizal (AM) fungi and Bacillus thuringiensis (Bt) were assayed and compared to Rhizophagus intraradices (Ri), Bacillus megaterium (Bm) or ...Pseudomonas putida (Psp) and non-inoculation on Trifolium repens in a natural arid soil under drought conditions. The autochthonous bacteria Bt and the allochthonous bacteria Psp increased nutrients and the relative water content and decreased stomatal conductance, electrolyte leakage, proline and APX activity, indicating their abilities to alleviate the drought stress. Mycorrhizal inoculation significantly enhanced plant growth, nutrient uptake and the relative water content, particularly when associated with specific bacteria minimizing drought stress-imposed effects. Specific combinations of autochthonous or allochthonous inoculants also contributed to plant drought tolerance by changing proline and antioxidative activities. However, non-inoculated plants had low relative water and nutrients contents, shoot proline accumulation and glutathione reductase activity, but the highest superoxide dismutase activity, stomatal conductance and electrolyte leakage. Microbial activities irrespective of the microbial origin seem to be coordinately functioning in the plant as an adaptive response to modulated water stress tolerance and minimizing the stress damage. The autochthonous AM fungi with Bt or Psp and those allochthonous Ri with Bm or Psp inoculants increased water stress alleviation. The autochthonous Bt showed the greatest ability to survive under high osmotic stress compared to the allochthonous strains, but when single inoculated or associated with Ri or AM fungi were similarly efficient in terms of physiological and nutritional status and in increasing plant drought tolerance, attenuating and compensating for the detrimental effect of water limitation.
Intensive agricultural practices are responsible for soil biological degradation. By stimulating indigenous arbuscular mycorrhizal fungi (AMF), cover cropping enhances soil health and promotes ...agroecosystem sustainability. Still, the legacy effects of cover crops (CCs) and the major factors driving the AM fungal community are not well known; neither is the influence of the specific CC. This work describes a field experiment established in Central Spain to test the effect of replacing winter fallow by barley (Hordeum vulgare L.) or vetch (Vicia sativa L.) during the intercropping of maize (Zea mays L.). We examined the community composition of the AMF in the roots and rhizosphere soil associated with the subsequent cash crop after 10 years of cover cropping, using Illumina technology. The multivariate analysis showed that the AMF communities under the barley treatment differed significantly from those under fallow, whereas no legacy effect of the vetch CC was detected. Soil organic carbon, electrical conductivity, pH, Ca and microbial biomass carbon were identified as major factors shaping soil AMF communities. Specific AMF taxa were found to play a role in plant uptake of P, Fe, Zn, Mn, and Cd, which may shed light on the functionality of these taxa. In our conditions, the use of barley as a winter CC appears to be an appropriate choice with respect to promotion of AMF populations and biological activity in agricultural soils with intercropping systems. However, more research on CC species and their legacy effect on the microbial community composition and functionality are needed to guide decisions in knowledge-based agriculture.
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•AMF communities under barley differed from those under fallow but not under vetch.•Cover crop and soil properties drive AMF community composition.•Barley was the most-suitable to promote the AMF populations and biological activity.
Abstract Background The comparison of the performance of two binary diagnostic tests is an important topic in Clinical Medicine. The most frequent type of sample design to compare two binary ...diagnostic tests is the paired design. This design consists of applying the two binary diagnostic tests to all of the individuals in a random sample, where the disease status of each individual is known through the application of a gold standard . This article presents an R program to compare parameters of two binary tests subject to a paired design. Results The “compbdt” program estimates the sensitivity and the specificity, the likelihood ratios and the predictive values of each diagnostic test applying the confidence intervals with the best asymptotic performance. The program compares the sensitivities and specificities of the two diagnostic tests simultaneously, as well as the likelihood ratios and the predictive values, applying the global hypothesis tests with the best performance in terms of type I error and power. When the global hypothesis test is significant, the causes of the significance are investigated solving the individual hypothesis tests and applying the multiple comparison method of Holm. The most optimal confidence intervals are also calculated for the difference or ratio between the respective parameters. Based on the data observed in the sample, the program also estimates the probability of making a type II error if the null hypothesis is not rejected, or estimates the power if the if the alternative hypothesis is accepted. The “compbdt” program provides all the necessary results so that the researcher can easily interpret them. The estimation of the probability of making a type II error allows the researcher to decide about the reliability of the null hypothesis when this hypothesis is not rejected. The “compbdt” program has been applied to a real example on the diagnosis of coronary artery disease. Conclusions The “compbdt” program is one which is easy to use and allows the researcher to compare the most important parameters of two binary tests subject to a paired design. The “compbdt” program is available as supplementary material.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The development of highly active and long‐term stable electrocatalysts for the cathode of proton‐exchange membrane fuel cells (PEMFC) is a paramount requirement for high performance and durable PEMFC ...stacks. In this regard, alloying Pt with rare earth metals (REM) has emerged as a promising approach. This short review summarizes and discusses the most relevant advances on Pt‐REM alloy electrocatalysts, from bulk polycrystalline surfaces to carbon supported nanostructures, for the oxygen reduction reaction (ORR), and their implementation in PEMFCs, and is a starting point to establish the challenges in synthesis and design and properties goals for novel Pt‐REM alloys.
Fuel cells: The recent progress on platinum‐rare earth alloys for the oxygen reduction reaction, from bulk polycrystalline surfaces to carbon supported nanostructures, is briefly discussed, identifying and establishing the challenges in synthesis and properties design for advanced electrocatalysts for fuel cells.
Biometrical sciences and disease diagnosis in particular, are often concerned with the analysis of associations for cross-classified data, for which distance association models give us a graphical ...interpretation for non-sparse matrices with a low number of categories. In this framework, usually binary exploratory and response variables are present, with analysis based on individual profiles being of great interest. For saturated models, we show the usual linear relationship for log-linear models is preserved in full dimension for the distance association parameterization. This enables a two-step procedure to facilitate the analysis and the interpretation of associations in terms of unfolding after the overall and main effects are removed. The proposed procedure can deal with cross-classified data for profiles by binary variables, and it is easy to implement using traditional statistical software. For disease diagnosis, the problems of a degenerate solution in the unfolding representation, and that of determining significant differences between the profile locations are addressed. A hypothesis test of independence based on odds ratio is considered. Furthermore, a procedure is proposed to determine the causes of the significance of the test, avoiding the problem of error propagation. The equivalence between a test for equality of odds ratio pairs and the test for equality of location for two profiles in the unfolding representation in the disease diagnosis is shown. The results have been applied to a real example on the diagnosis of coronary disease, relating the odds ratios with performance parameters of the diagnostic test.
The global rise in urbanization and industrial activity has led to the production and incorporation of foreign contaminant molecules into ecosystems, distorting them and impacting human and animal ...health. Physical, chemical, and biological strategies have been adopted to eliminate these contaminants from water bodies under anthropogenic stress. Biotechnological processes involving microorganisms and enzymes have been used for this purpose; specifically, laccases, which are broad spectrum biocatalysts, have been used to degrade several compounds, such as those that can be found in the effluents from industries and hospitals. Laccases have shown high potential in the biotransformation of diverse pollutants using crude enzyme extracts or free enzymes. However, their application in bioremediation and water treatment at a large scale is limited by the complex composition and high salt concentration and pH values of contaminated media that affect protein stability, recovery and recycling. These issues are also associated with operational problems and the necessity of large-scale production of laccase. Hence, more knowledge on the molecular characteristics of water bodies is required to identify and develop new laccases that can be used under complex conditions and to develop novel strategies and processes to achieve their efficient application in treating contaminated water. Recently, stability, efficiency, separation and reuse issues have been overcome by the immobilization of enzymes and development of novel biocatalytic materials. This review provides recent information on laccases from different sources, their structures and biochemical properties, mechanisms of action, and application in the bioremediation and biotransformation of contaminant molecules in water. Moreover, we discuss a series of improvements that have been attempted for better organic solvent tolerance, thermo-tolerance, and operational stability of laccases, as per process requirements.
We study the spin waves of the triangular skyrmion crystal that emerges in a two-dimensional spin lattice model as a result of the competition between Heisenberg exchange, Dzyalonshinkii-Moriya ...interactions, Zeeman coupling and uniaxial anisotropy. The calculated spin wave bands have a finite Berry curvature that, in some cases, leads to non-zero Chern numbers, making this system topologically distinct from conventional magnonic systems. We compute the edge spin-waves, expected from the bulk-boundary correspondence principle, and show that they are chiral, which makes them immune to elastic backscattering. Our results illustrate how topological phases can occur in self-generated emergent superlattices at the mesoscale.
Aims Our study was intended to elucidate the involvement of three species of arbuscular mycorrhizal fungi (AMF) in the formation and stabilization of aggregates in semiarid soils with different ...textures and calcium carbonate contents. Methods We used a root-hyphae compartment approach to compare the effect of three AMF (Rhizophagus irregularis, Septoglomus deserticola, and Gigaspora gigantea) on the structural stability of the hyphosphere (root-free hyphae) and mycorrhizosphere (hyphae + root) soil of Olea europaea plants grown in two soils differing in their texture (sandy loam and silty loam) and calcium carbonate content. Results Only the R. irregularis strain significantly increased the percentage of stable aggregates in both types of soil, being the increases higher in the hyphosphere compartment (on average, about 30 % compared to noninoculated soil). In the hyphosphere compartment of both soils, the hyphal length developed by plants inoculated with R. irregularis was 81 % greater than that of non-inoculated plants. The effect of the AMF on soil aggregation was mediated by mechanical entanglement of mycorrhizal fungal hyphae but without a contribution of labile carbohydrates. Conclusion The ability of extraradical hyphae to improve soil structure was independent of the soil texture and content of carbonates.
The rhizosphere microbiome plays a crucial role in the ability of plants to colonize and thrive in stressful conditions such as drought, which could be decisive for the success of exotic plant ...invasion in the context of global climate change. The aim of this investigation was to examine differences in the composition, structure, and functional traits of the microbial community of the invader Nicotiana glauca R.C. Graham and native species growing at seven different Mediterranean semiarid locations under two distinct levels of water availability, corresponding to the wet and dry seasons. The results show that the phylum Actinobacteriota was an indicator phylum of the dry season as well as for the community of N. glauca. The dominant indicator bacterial families of the dry season were 67–14 (unclassified family), Pseudonocardiaceae, and Sphingomonadaceae, being relatively more abundant in the invasive rhizosphere. The relative abundances of the indicator fungal families Aspergillaceae (particularly the indicator genus Aspergillus), Glomeraceae, and Claroideoglomeraceae were higher in the invasive rhizosphere. The relative abundance of mycorrhizal fungi was higher in the invasive rhizosphere in the dry season (by about 40 % in comparison to that of native plants), without significant differences between invasive and native plants in the wet season. Bacterial potential functional traits related to energy and precursor metabolites production and also biosynthesis of cell wall, cofactors, vitamins, and amino acids as well as catabolic enzymes involved in the P cycle prevailed in the invasive rhizosphere under drought conditions. This study shows that the pronounced and beneficial shifts in the microbiome assembly and functions in the rhizosphere of N. glauca under conditions of low soil water availability can represent a clear advantage for its establishment.
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•Drought resistant bacteria were prevalent in the invader rhizosphere.•Actinobacteriota was an indicator phylum of the dry season and invader microbiome.•Relative abundance of AMF was higher in invasive rhizosphere in dry season.•Invader promoted specific bacterial functionality in response to drought.
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