Studying the Structure and Properties of Epoxy Composites Modified by Original and Functionalized with Hexamethylenediamine by Electrochemically Synthesized Graphene Oxide.

In this study, we used multilayer graphene oxide (GO) obtained by anodic oxidation of graphite powder in 83% sulfuric acid. The modification of GO was carried out by its interaction with hexamethylenediamine (HMDA) according to the mechanism of nucleophilic substitution between the amino group of HMDA (HMDA) and the epoxy groups of GO, accompanied by partial reduction of multilayer GO and an increase in the deformation of the carbon layers. The structure and properties of modified HMDA-GO were characterized using research methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy and Raman spectroscopy. The conducted studies show the effectiveness of using HMDA-OG for modifying epoxy composites. Functionalizing treatment of GO particles helps reduce the free surface energy at the polymer-nanofiller interface and increase adhesion, which leads to the improvement in physical and mechanical characteristics of the composite material. The results demonstrate an increase in the strength and elastic modulus in bending by 48% and 102%, respectively, an increase in the impact strength by 122%, and an increase in the strength and elastic modulus in tension by 82% and 47%, respectively, as compared to the pristine epoxy composite which did not contain GO-HMDA. It has been found that the addition of GO-HMDA into the epoxy composition initiates the polymerization process due to the participation of reactive amino groups in the polymerization reaction, and also provides an increase in the thermal stability of epoxy nanocomposites.

Investigating the Structure and Properties of Epoxy Nanocomposites Containing Nanodiamonds Modified with Aminoacetic Acid.

This paper presents a study on the prospects of functionalizing nanodiamonds (NDs) with aminoacetic acid to obtain high-strength composites based on an epoxy matrix. The impact of the functionalization of the ND surface with aminoacetic acid in various concentrations on the properties of the epoxy composite was assessed. The success of grafting amine onto the ND surface was confirmed by X-ray phase analysis and IR spectroscopy. The results show a significant decrease in the average size of ND particles, from 400 nm for the pristine ones to 35 nm, and the contact angle, from 27° to 22°, with an increase in the specific surface area after treatment with a 5% solution of aminoacetic acid. Reducing the average size of NDs allows them to be better distributed throughout the epoxy matrix, which, as a result of the formation of chemical interaction at the matrix-nanofiller phase interface, can significantly increase the strength of the obtained composite. The addition of NDs treated with aminoacetic acid ensures an increase in the deformation-strength properties of epoxy composites by 19-23% relative to an epoxy composite containing the pristine NDs. Moreover, the presence of functionalized NDs significantly influences the structure and thermal stability of the epoxy nanocomposite.

Mapping Asia Plants: The Threat Status and Influencing Factors of Rare and Endangered Vascular Plant Species in North Asia (Asian Russia).

In order to effectively protect rare and endangered plants, 27 provincial-level administrative regions in North Asia (the Asian part of Russia) have compiled and published local Red Data Books. In this study, the names (with synonyms) of vascular plants in the 27 provincial Red Books were digitalized and merged into a database of rare and endangered vascular plants in North Asia. The purpose is to reflect the species composition, geographic distribution pattern, and protection level of these plants and their inclusion in the national Russian Red Data Book and the IUCN Red List, and provide a reference for formulating conservation strategies. The dataset has a total of 2079 species, 160 subspecies, and 53 varieties belonging to 667 genera and 143 families. It contains data on 2292 taxa, including family name, genus name, species name and synonyms, protection level, and other information. We also analyzed the main influencing factors, existing problems of rare and endangered vascular plant species, and suggestions for addressing them. We conclude that, to date, the IUCN criteria have not been applied consistently in all regions, leading to an excessive number of species being recorded in the Red Data Books of Asian Russia; specifically, one-third of all floral species are in the regional Red Data Books.

Microwave Modification of an Epoxy Basalt-Filled Oligomer to Improve the Functional Properties of a Composite Based on It.

The purpose of this work is to study the influence of the electric field strength of an electromagnetic wave with the maximum modifying effect on an epoxy basalt-filled oligomer, which is of great scientific and practical importance for the development of microwave oligomer modification technology. The optimal modes of microwave modification, under which the highest values of the mechanical properties of an epoxy basalt-filled polymer composite material are obtained, are identified: power of 400 W and an exposure time of 24 s. At the same time, the breaking stress in bending increases by 20%, the impact strength increases by 2 times, and hardness increases by 31%. A slight increase of 4.5% in heat resistance is noted compared to the composite obtained on the basis of an oligomer unmodified in the microwave electromagnetic field. The results of resistance to various aggressive environments are obtained, which show that the studied physical and mechanical characteristics of the epoxy basalt-filled material after exposure to an aggressive environment decrease by less than 14%, which corresponds to their good resistance to an aggressive environment. It is established that the effect of the microwave electromagnetic field on an epoxy basalt-filled oligomer is an effective modification method that improves physical and mechanical characteristics with a high level of temporal stability to climatic influences, with a coefficient of property retention of more than 90%.

Transcriptomic Analysis of Flowering Time Genes in Cultivated Chickpea and Wild Cicer.

Chickpea (Cicer arietinum L.) is a major grain legume and a good source of plant-based protein. However, comprehensive knowledge of flowering time control in Cicer is lacking. In this study, we acquire high-throughput transcriptome sequencing data and analyze changes in gene expression during floral transition in the early flowering cultivar ICCV 96029, later flowering C. arietinum accessions, and two wild species, C. reticulatum and C. echinospermum. We identify Cicer orthologs of A. thaliana flowering time genes and analyze differential expression of 278 genes between four species/accessions, three tissue types, and two conditions. Our results show that the differences in gene expression between ICCV 96029 and other cultivated chickpea accessions are vernalization-dependent. In addition, we highlight the role of FTa3, an ortholog of FLOWERING LOCUS T in Arabidopsis, in the vernalization response of cultivated chickpea. A common set of differentially expressed genes was found for all comparisons between wild species and cultivars. The direction of expression change for different copies of the FT-INTERACTING PROTEIN 1 gene was variable in different comparisons, which suggests complex mechanisms of FT protein transport. Our study makes a contribution to the understanding of flowering time control in Cicer, and can provide genetic strategies to further improve this important agronomic trait.

Effect of Microwave Irradiation at Different Stages of Manufacturing Unsaturated Polyester Nanocomposite.

The possibility of using microwave radiation at various stages of obtaining an unsaturated polyester composite modified with carbon nanotubes was studied. The optimal content of MWCNTs in the system was experimentally selected, having the best effect on the strength of the composite. The effect of the microwave field on the properties of a polyester composite during the microwave treatment of an oligomer, a polymerized composite, and MWCNTs before their addition into the oligomer was studied. The processes of the structure formation, the structure of the composite, the effect of the microwave radiation on MWCNTs, and the thermal stability of the resulting composites were considered.

Reinforced Epoxy Composites Modified with Functionalized Graphene Oxide.

The possibility of using graphene oxide as a modifying additive for polymer fiber-reinforced composites based on epoxy resin and basalt roving has been studied. The content of graphene oxide in the system has been experimentally selected, which has the best effect on the physico-mechanical properties of the obtained polymer composite material. The efficiency of the modification of the graphene oxide surface with APTES finishing additives and aminoacetic acid, which provides chemical interaction at the polymer matrix-filler interface, has been considered. The influence of graphene oxide and functionalizing additives on the polymer curing process was investigated using the thermometric method and differential scanning calorimetry.

A grid-based database on vascular plant distribution in the Meshchersky National Park, Ryazan Oblast, Russia.

BACKGROUND: Ryazan Oblast, situated in the central part of European Russia, has a long tradition of biodiversity research. Large distributional, ecological and phenological data on various taxonomic groups are available from this territory, mainly in the form of paper publications items, undigitised museum collections and archival sources. The purpose of this dataset is to deliver floristic materials, collected by the authors in the Meshchera Lowlands in the form of GBIF-mediated electronic data, to a wider audience. The dataset covers wild tracheophytes (native species, naturalised aliens and casuals) of the Meshchersky National Park. In 2020, it was used for the production of grid maps in "Flora of the Meschchersky National Park: checklist and atlas". NEW INFORMATION: The dataset contains 14,476 grid records of 817 taxa (806 species and hybrids, ten species aggregates and one genus). Most of the records (82.4%) were made in the field by A.V. Shcherbakov, M.V. Kazakova, N.V. Lyubeznova and A.D. Pastushenko in 2017 and 2018. The dataset includes only one occurrence per species per grid square. Georeferences are based on the WGS84 grid scheme with 55 squares measuring ca. 25 km2 (2.5' lat. × 5' long.). Each occurrence is linked to the corresponding grid square centroid; therefore, actual coordinates, habitat details and voucher information are unavailable. As of September 2021, the dataset on the flora of the Meshchersky National Park represents the second largest dataset on the biodiversity of Ryazan Oblast, Russia, published in GBIF.

Sphagnum mosses harbour highly specific bacterial diversity during their whole lifecycle.

Knowledge about Sphagnum-associated microbial communities, their structure and their origin is important to understand and maintain climate-relevant Sphagnum-dominated bog ecosystems. We studied bacterial communities of two cosmopolitan Sphagnum species, which are well adapted to different abiotic parameters (Sphagnum magellanicum, which are strongly acidic and ombrotrophic, and Sphagnum fallax, which are weakly acidic and mesotrophic), in three Alpine bogs in Austria by a multifaceted approach. Great differences between bacterial fingerprints of both Sphagna were found independently from the site. This remarkable specificity was confirmed by a cloning and a deep sequencing approach. Besides the common Alphaproteobacteria, we found a discriminative spectrum of bacteria; although Gammaproteobacteria dominated S. magellanicum, S. fallax was mainly colonised by Verrucomicrobia and Planctomycetes. Using this information for fluorescent in situ hybridisation analyses, corresponding colonisation patterns for Alphaproteobacteria and Planctomycetes were detected. Bacterial colonies were found in high abundances inside the dead big hyalocytes, but they were always connected with the living chlorocytes. Using multivariate statistical analysis, the abiotic factors nutrient richness and pH were identified to modulate the composition of Sphagnum-specific bacterial communities. Interestingly, we found that the immense bacterial diversity was transferred via the sporophyte to the gametophyte, which can explain the high specificity of Sphagnum-associated bacteria over long distances. In contrast to higher plants, which acquire their bacteria mainly from the environment, mosses as the phylogenetically oldest land plants maintain their bacterial diversity within the whole lifecycle.

Characterization of Bacillus subtilis HC8, a novel plant-beneficial endophytic strain from giant hogweed.

Thirty endophytic bacteria were isolated from various plant species growing near Saint-Petersburg, Russia. Based on a screening for various traits, including plant-beneficial properties and DNA fragment patterns, potential siblings were removed. The remaining isolates were taxonomically identified using 16S rDNA sequences and potential human and plant pathogens were removed. The remaining strains were tested for their ability to promote radish root growth and to protect tomato plants against tomato foot and root rot. One strain, Bacillus subtilis HC8, isolated from the giant hogweed Heracleum sosnowskyi Manden, significantly promoted plant growth and protected tomato against tomato foot and root rot. Metabolites possibly responsible for these plant-beneficial properties were identified as the hormone gibberellin and (lipo)peptide antibiotics respectively. The antibiotic properties of strain HC8 are similar to those of the commercially available plant-beneficial strain Bacillus amyloliquefaciens FZB42. However, thin layer chromatography profiles of the two strains differ. It is speculated that endophytes such as B. subtilis HC8 contribute to the fast growth of giant hogweed.