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•Investigated materials are ferri- or antiferromagnetic materials.•Investigated materials present good ferroelectric properties.•Investigated materials present magneto-crystalline ...anisotropy and anisotropic ferroelectric response.•The effect of double magnetism on multiferroism of R3c structure was evaluated.•The PbFeO3 materials present half-metallic behavior as a consequence of spin contamination on Pb atoms.
Multiferroic materials, such as the BiFeO3, have been investigated as emergent material to technological purposes. Other multiferroic materials reported in literature are PbNiO3, NiTiO3 and FeTiO3. In this work, we decide to investigate a new series of multiferroic materials composed by Fe3+ in A and B sites of R3c structures, resulting in AlFeO3, FeAlO3, FeVO3, BiFeO3 and PbFeO3. Therefore, a DFT/B3LYP investigation was employed to evaluate the structural, electronic, topological analysis, ferroelectric and magnetic properties, as well as the magnetoelectric coupling. Our results indicates that the multiferroism were theoretically evidenced in these materials since a magnetic resultant is oriented along 1 1 1 direction of unit cell (as ferromagnetic as antiferromagnetic materials) while the ferroelectricity is oriented along z 0 0 1 direction. In all materials, it was observed a D3d distortion on clusters and its characteristic energy levels pattern for t2g and eg. In particular, the electronic structure of PbFeO3 material indicates that Pb atoms presents a spin contamination caused by unpaired electrons from Fe in the structure and also suggesting a half-metallic ferromagnetism pointing it as important alternatives to spintronic devices development. The results for energetic stability suggest that all materials are stable under high pressures and room conditions.
The crystal/electronic structure and vibrational properties of the Cu
x
TiSe
2
intercalation compounds were studied combining experimental and theoretical techniques. The Cu added into the TiSe
2
...matrix was characterized as an intercalant atom into van der Waals gaps from Raman spectroscopy analysis. Theoretical and experimental data indicate the Cu-intercalation effect on the crystalline structure as a local disorder affecting TiSe
6
clusters from Se Se layers, which results in a volume expansion. A significant charge transfer from Cu atoms to the host lattice results in a change from Ti
4+
to Ti
3+
species, narrowing the band-gap and increasing the superconductivity of the material.
The crystal/electronic structure and vibrational properties of the Cu
x
TiSe
2
intercalation compounds were studied combining experimental and theoretical techniques.
Electrochemical and photoelectrochemical techniques have been employed to investigate the electronic energy level modification of N-doped TiO
2
and to elucidate its properties and roles, particularly ...the electron transfer rate and influence on recombination, in a simple and facile manner. However, the results obtained cannot be easily interpreted and they need comparisons with theoretical calculations. In this study, photoelectrochemical measurements were conducted to investigate the effect of N-doping on TiO
2
nanomaterials, and the results obtained were compared with theoretical calculations. Band-gap values calculated by diffuse reflectance UV-vis spectroscopy were used together with photoelectrochemical measurements of TiO
2
and TiO
2
: N flat-band potentials to create a scheme of the energy-level band edges. In addition, this method confirmed the creation of energetic inter-levels by the N-doping process, as predicted by theoretical calculations. The replacement of an oxygen atom by nitrogen atom in the anatase structure shows a modification of the energetic levels, caused by a shift of the upper energy level; this shift was caused by local structural disorder. From the photoelectrochemical results, it is possible to confirm that the electron concentration in the TiO
2
photoelectrode is higher than that in the TiO
2
: N photoelectrode; due to an increase in the recombination of electrons and holes because of the creation of inter-levels in the TiO
2
: N band-gap. In addition, theoretical analysis indicated a possibility of direct transfer of electrons into the band-gap of TiO
2
: N. This combined approach was useful for interpreting many unclear results with respect to the photocatalytic activity of TiO
2
: N.
In N-doping on TiO
2
nanomaterial occurs a big decrease of band-gap (1 eV); however, its photocatalysis is low. We clarify such fact from effective mass,
i.e.
, the electron-hole recombination is more than creation of electron-hole pair.
Restoring the ecosystems of the Cerrado biome is challenging considering the diversity of phytophysiognomies present in the biome, some of which are composed of species from different strata ...(herbaceous, shrubby, and arboreal), which increases the complexity of restructuring the floristic composition. Other factors was involved, such as soil quality, which directly influences the success of restoration, water storage, and nutrients, the financial costs, and a slow ecological process, due to the adverse circumstances found in the area. be restored. The strong anthropogenic interventions by mining processes reduce dramatically the physical and nutritional composition of the soil. We studied two restoration areas in Paracatu, Brazil, to examine their edaphic conditions six years after mining activities ceased and relate them to the status of the restoration process. In 2009, a Cerrado restoration were established in an area previously explored for gravel extraction. Plants were sampled and identified in 11 transects along the planting lines. The diameter base (DB) and total height (HT) were measured. The physical/chemical quality of the soil substrate was determined using a collection of samples in open trenches at four types of points: Cerrado (TC); dead plant pits (TM); seedling pits having living individuals of the most abundant species (TT); and those of the second-most abundant species (TE). Cecropia pachystachya Trécul and Tapirira guianensis Aubl. were most abundant and demonstrated the potential to thrive in areas degraded by mining having low mortality rates and growth at relatively DB and HT. The physical quality indicators in the gravel pits were not limiting, indicating that substrate preparation was efficient in this regard. The organic matter content in TM, TT, and TE was low in comparison to that of TC, and the chemical conditions in the TE pit substrates were similar to those in TM pits, suggesting C. pachystachya is a species with good plasticity, whereas T. guianensis is present in pits with higher levels of phosphorus.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The development of biocatalysts capable of fermenting xylose, a five-carbon sugar abundant in lignocellulosic biomass, is a key step to achieve a viable production of second-generation ethanol. In ...this work, a robust industrial strain of Saccharomyces cerevisiae was modified by the addition of essential genes for pentose metabolism. Subsequently, taken through cycles of adaptive evolution with selection for optimal xylose utilization, strains could efficiently convert xylose to ethanol with a yield of about 0.46 g ethanol/g xylose. Though evolved independently, two strains carried shared mutations: amplification of the xylose isomerase gene and inactivation of ISU1, a gene encoding a scaffold protein involved in the assembly of iron-sulfur clusters. In addition, one of evolved strains carried a mutation in SSK2, a member of MAPKKK signaling pathway. In validation experiments, mutating ISU1 or SSK2 improved the ability to metabolize xylose of yeast cells without adaptive evolution, suggesting that these genes are key players in a regulatory network for xylose fermentation. Furthermore, addition of iron ion to the growth media improved xylose fermentation even by non-evolved cells. Our results provide promising new targets for metabolic engineering of C5-yeasts and point to iron as a potential new additive for improvement of second-generation ethanol production.
Biological nitrogen fixation (BNF) is a key process for the N input in agriculture, with outstanding economic and environmental benefits from the replacement of chemical fertilizers. However, not all ...symbioses are equally effective in fixing N
, and a major example relies on the high contribution associated with the soybean (
, contrasting with the low rates reported with the common bean (
) crop worldwide. Understanding these differences represents a major challenge that can help to design strategies to increase the contribution of BNF, and next-generation sequencing (NGS) analyses of the nodule and root microbiomes may bring new insights to explain differential symbiotic performances. In this study, three treatments evaluated in non-sterile soil conditions were investigated in both legumes: (i) non-inoculated control; (ii) inoculated with host-compatible rhizobia; and (iii) co-inoculated with host-compatible rhizobia and
. In the more efficient and specific symbiosis with soybean,
presented a high abundance in nodules, with further increases with inoculation. Contrarily, the abundance of the main
symbiont was lower in common bean nodules and did not increase with inoculation, which may explain the often-reported lack of response of this legume to inoculation with elite strains. Co-inoculation with
decreased the abundance of the host-compatible rhizobia in nodules, probably because of competitiveness among the species at the rhizosphere, but increased in root microbiomes. The results showed that several other bacteria compose the nodule microbiomes of both legumes, including nitrogen-fixing, growth-promoters, and biocontrol agents, whose contribution to plant growth deserves further investigation. Several genera of bacteria were detected in root microbiomes, and this microbial community might contribute to plant growth through a variety of microbial processes. However, massive inoculation with elite strains should be better investigated, as it may affect the root microbiome, verified by both relative abundance and diversity indices, that might impact the contribution of microbial processes to plant growth.
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•D3 Grimme’s dispersion showed low correction for all evaluated properties.•HSE06 functional presented more deviation because of Hartree-Fock exchange term.•Low vibrations were poorly ...described.•PBE0 functional described better the properties.
Superconductivity is one of the most interesting electrical phenomena found in Physical Science. The null electrical resistance provides a unique free displacement for the electrons into the material. TiSe2 is a superconductor material below 4K, creating a charge density wave as electrical propagation. Gaussian basis sets or exchange–correlation functionals poorly described the high interaction distance as van der Waals force because of low exchange–correlation energy. One physical–mathematical tool to indicate long-range distance is the Grimme's or D3 dispersion. In this work, quantum simulations based on DFT using periodic models depicted in CRYSTAL17 code investigated the TiSe2 material regarding PBE0, HSE06, and B3LYP functionals and Grimme's dispersion. In particular, the high covalent feature on the Ti–Se chemical bond is challenging for DFT functionals, while van der Waals interaction between lamellas is essential for crystalline structure. Then, relative errors quantified the functional descriptions to evaluate the influence of hybrid and parameterized hybrid functionals on this critical material's structural, electronic, and vibrational properties.
The main objective of this study was to evaluate
strain CMRP 4490 regarding its ability to inhibit soil-borne plant pathogens and to increase plant growth. The study included evaluation of
antifungal ...control, sequencing the bacterial genome, mining genes responsible for the synthesis of secondary metabolites, root colonization ability, and greenhouse studies for the assessment of plant growth-promoting ability. The strain was obtained from soil samples in the north of Paraná in Brazil and was classified as a
, which is considered a promising biological control agent.
assay showed that
CMRP 4490 presented antagonistic activity against
,
,
, and
with a mycelial growth inhibition of approximately 60%, without any significant difference among them. To well understand this strain and to validate its effect on growth-promoting rhizobacteria, it was decided to explore its genetic content through genome sequencing,
, and greenhouse studies. The genome of CMRP 4490 was estimated at 3,996,396 bp with a GC content of 46.4% and presents 4,042 coding DNA sequences. Biosynthetic gene clusters related to the synthesis of molecules with antifungal activity were found in the genome. Genes linked to the regulation/formation of biofilms, motility, and important properties for rhizospheric colonization were also found in the genome. Application of CMRP 4490 as a coating film on soybean increased from 55.5 to 64% on germination rates when compared to the control; no differences were observed among treatments for the maize germination. The results indicated that
CMRP 4490 could be a potential biocontrol agent with plant growth-promoting ability.
Biological nitrogen fixation is a key process for agricultural production and environmental sustainability, but there are comparatively few studies of symbionts of tropical pasture legumes, as well ...as few described species of the genus Bradyrhizobium, although it is the predominant rhizobial genus in the tropics. A detailed polyphasic study was conducted with two strains of the genus Bradyrhizobium used in commercial inoculants for tropical pastures in Brazil, CNPSo 1112T, isolated from perennial soybean (Neonotonia wightii), and CNPSo 2833T, from desmodium (Desmodium heterocarpon). Based on 16S-rRNA gene phylogeny, both strains were grouped in the Bradyrhizobium elkanii superclade, but were not clearly clustered with any known species. Multilocus sequence analysis of three (glnII, gyrB and recA) and five (plus atpD and dnaK) housekeeping genes confirmed that the strains are positioned in two distinct clades. Comparison with intergenic transcribed spacer sequences of type strains of described species of the genus Bradyrhizobium showed similarity lower than 93.1 %, and differences were confirmed by BOX-PCR analysis. Nucleotide identity of three housekeeping genes with type strains of described species ranged from 88.1 to 96.2 %. Average nucleotide identity of genome sequences showed values below the threshold for distinct species of the genus Bradyrhizobium ( < 90.6 %), and the value between the two strains was also below this threshold (91.2 %). Analysis of nifH and nodC gene sequences positioned the two strains in a clade distinct from other species of the genus Bradyrhizobium. Morphophysiological, genotypic and genomic data supported the description of two novel species in the genus Bradyrhizobium, Bradyrhizobium tropiciagri sp. nov. (type strain CNPSo 1112T = SMS 303T = BR 1009T = SEMIA 6148T = LMG 28867T) and Bradyrhizobium embrapense sp. nov. (type strain CNPSo 2833T = CIAT 2372T = BR 2212T = SEMIA 6208T = U674T = LMG 2987).
In this study, ab initio density functional theory calculations were performed on ATiO3 (A = Mn, Fe, Ni) materials for multiferroic applications. Structural, magnetic, electronic and topological ...analysis were investigated as regard the A-site cation effect. Concerning the prediction of new multiferroic candidates in silico, the role of different exchange-correlation functionals was reviewed. From such properties was verified that PBE0 functional performs the best for ATiO3 compounds overcoming the deficiency of standard LDA and PBESol functionals and get the better of B3LYP, PBE0+D and B3LYP+D. Regarding the A-site cation effect, calculated structural parameters follow the ionic radii trend moving from Mn to Ni, resulting in more ordered AO6 clusters; while, the TiO6 distortion increases. Using magneto-structural and magneto-electronic parameters, the antiferromagnetic exchange coupling constant was rationalized from GKA rules. The increase of the antiferromagnetic order along the transition metal series was explained from the 3d orbital occupancy and A-O bond interactions. DOS and band structure profiles clarify the semiconductor behavior as regard the 3d crystal field splitting for both A-site and Ti cations. Further, electronic results suggest the existence of intermetallic connection (A-O-Ti-O-A); whereas, topological analysis in the framework of quantum theory of atom in molecules was carried out to evaluate the A-O and Ti-O bond interaction through the analyses of (grad)2 rho sign at bond critical point and of the charge-transfer parameter obtained from net charges.
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