Improved Dielectric Properties of Epoxy Nano Composites

Epoxy-based nanodielectrics with 2, 5 and 7 wt.% of organically modified montmorillonite clay (oMMT) were prepared using high shear melt mixing technique. The interface of oMMT and epoxy of the nanodielectrics play a very important role in improving electrical, mechanical, thermal and wear properties. Therefore detailed study on the interfacial effects of filler-matrix has been investigated for understanding the chemical bonding using Fourier transform infrared spectroscopy (FTIR) and the cross linking between polymer and filler was studied using glass transition temperature (Tg) through differential scanning calorimetry (DSC). Further, positron annihilation lifetime spectroscopy (PALS) was used to determine precise and accurate value of free volume of the nanodielectrics. The interaction between the nanoparticles and polymer chains has a direct bearing on dielectric strength characteristics of the epoxy-oMMT nanocomposite system and accordingly, the ac dielectric strength of the nanodielectrics increases with the addition of oMMT into epoxy up to 5 wt.% and further increase in filler loading (7 wt.%) causes decrease in ac dielectric strength

Mechanical and Tribological Properties of Epoxy Nano Composites for High Voltage Applications

The tribological and mechanical properties of organomodified montmorillonite (oMMT)-incorporated Epoxy (Epoxy-oMMT), vinyl ester (vinyl ester-oMMT) and titanium dioxide (TiO2)-filled Epoxy (Epoxy-TiO2) nanocomposites are discussed below. Implications of introducing oMMT and TiO2 nanoparticles on mechanical and dry sliding wear properties are presented using micrographs of cast samples and through observations of wear affected surface of nanocomposites. Distribution of nanoparticles and their influence on properties are being emphasized for understanding the wear properties. The data on mechanical and tribological properties determined experimentally are compared with published literature. The main focus is to highlight the importance of nanofillers in the design of wear-resistant thermoset polymer composites. A detailed study of strength and moduli of Epoxy-oMMT, Epoxy-TiO2 and vinyl ester-oMMT nanocomposites was taken up as a part of the investigation. A discussion on density, hardness, tensile, flexural test data, and friction and wear of nanocomposites and analysis of results by comparison with prevalent theoretical models and published results of experiments are presented

Editorial: Breeding Innovations in Underutilized Temperate Fruit Trees

The recent growing interest in minor species (i.e., fig, pomegranate, feijoa, etc.) has recently driven new research on breeding and genetics to address producer and consumer traits. Since these species have received little attention from the scientific community, they were less improved via conventional breeding, and lacked detailed genomic information on important traits. This lack of data, together with a general poor genetic knowledge of these species, has limited a wider cultivation of varieties with improved characteristics

Synteny analysis in Rosids with a walnut physical map reveals slow genome evolution in long-lived woody perennials.

BackgroundMutations often accompany DNA replication. Since there may be fewer cell cycles per year in the germlines of long-lived than short-lived angiosperms, the genomes of long-lived angiosperms may be diverging more slowly than those of short-lived angiosperms. Here we test this hypothesis.ResultsWe first constructed a genetic map for walnut, a woody perennial. All linkage groups were short, and recombination rates were greatly reduced in the centromeric regions. We then used the genetic map to construct a walnut bacterial artificial chromosome (BAC) clone-based physical map, which contained 15,203 exonic BAC-end sequences, and quantified with it synteny between the walnut genome and genomes of three long-lived woody perennials, Vitis vinifera, Populus trichocarpa, and Malus domestica, and three short-lived herbs, Cucumis sativus, Medicago truncatula, and Fragaria vesca. Each measure of synteny we used showed that the genomes of woody perennials were less diverged from the walnut genome than those of herbs. We also estimated the nucleotide substitution rate at silent codon positions in the walnut lineage. It was one-fifth and one-sixth of published nucleotide substitution rates in the Medicago and Arabidopsis lineages, respectively. We uncovered a whole-genome duplication in the walnut lineage, dated it to the neighborhood of the Cretaceous-Tertiary boundary, and allocated the 16 walnut chromosomes into eight homoeologous pairs. We pointed out that during polyploidy-dysploidy cycles, the dominant tendency is to reduce the chromosome number.ConclusionSlow rates of nucleotide substitution are accompanied by slow rates of synteny erosion during genome divergence in woody perennials

Citotoksičnost, inhibicija agregacije trombocita i antioksidativna aktivnost ekstrakata biljke Curcuma amada Roxb.

Mango ginger (Curcuma amada Roxb.) is a unique spice having morphological resemblance to ginger but imparts raw mango flavour. The sequential extraction of mango ginger rhizome powder was carried out using hexane, chloroform, ethyl acetate, acetone, methanol and water. The phenolic content was the highest in methanol extract, followed by acetone, ethyl acetate and water extracts. Among these, chloroform extract exhibited high lipid peroxidation inhibitory activity and metal chelating activity, whereas ethyl acetate extract showed high DPPH radical scavenging activity and superoxide radical scavenging activity. Mango ginger extracts also showed potential platelet aggregation inhibitory activity and cytotoxicity properties.Curcuma amada Roxb. jedinstveni je začin jer morfološki nalikuje đumbiru, a po okusu je sličan mangu. Provedena je sekvencijska ekstrakcija praha dobivenog od rizoma te biljke pomoću heksana, kloroforma, etilnog acetata, acetona, metanola i vode. Udjel fenola bio je najveći u ekstraktu dobivenom pomoću metanola, zatim acetona i etilnog acetata, a najmanji u vodenom ekstraktu. Ekstrakt dobiven pomoću kloroforma imao je najveću sposobnost inhibicije peroksidacije lipida i keliranja metala, a onaj dobiven pomoću etilnog acetata najbolje svojstvo uklanjanja DPPH i superoksidnih radikala. Ekstrakti biljke Curcuma amada Roxb. imali su i sposobnost inhibicije agregacije trombocita te citotoksična svojstva

Genetic diversity and differentiation within and between cultivated (Vitis vinifera L. ssp. sativa) and wild (Vitis vinifera L. ssp. sylvestris) grapes

Genetic characterization of 502 diverse grape accessions including 342 cultivated (V. vinifera ssp. sativa) and 160 wild (V. vinifera ssp. sylvestris) grapes showed considerable genetic diversity among accessions. A total of 117 alleles were detected across eight SSR loci with the average of 14 alleles per locus. The genetic diversity of wild grapes was slightly lower than that observed in the cultivated grapes probably due to small populations and severe natural selection leading to drift and loss of alleles and heterozygosity in wild grapes. The distance cluster analysis (CA) supported the classical ecogeographic groups with moderate genetic differentiation among them. There was a greater affinity of Occidentalis grape to wild grape from the Caucasus than other groups. However, a number of low to moderate frequency alleles that are present in the cultivated grape are not represented in the wild grape.

Patterns of genomic and phenomic diversity in wine and table grapes.

Grapes are one of the most economically and culturally important crops worldwide, and they have been bred for both winemaking and fresh consumption. Here we evaluate patterns of diversity across 33 phenotypes collected over a 17-year period from 580 table and wine grape accessions that belong to one of the world's largest grape gene banks, the grape germplasm collection of the United States Department of Agriculture. We find that phenological events throughout the growing season are correlated, and quantify the marked difference in size between table and wine grapes. By pairing publicly available historical phenotype data with genome-wide polymorphism data, we identify large effect loci controlling traits that have been targeted during domestication and breeding, including hermaphroditism, lighter skin pigmentation and muscat aroma. Breeding for larger berries in table grapes was traditionally concentrated in geographic regions where Islam predominates and alcohol was prohibited, whereas wine grapes retained the ancestral smaller size that is more desirable for winemaking in predominantly Christian regions. We uncover a novel locus with a suggestive association with berry size that harbors a signature of positive selection for larger berries. Our results suggest that religious rules concerning alcohol consumption have had a marked impact on patterns of phenomic and genomic diversity in grapes

Fabrication, Mechanical and Wear Properties of Aluminum (Al6061)-Silicon Carbide-Graphite Hybrid Metal Matrix Composites

In recent times, the use of aluminum alloy-based Hybrid Metal Matrix Composites (HMMCs) is being increased in aerospace and automotive applications. HMMCs compensate for the low desirable properties of each filler used. However, the mechanical properties of HMMCs are not well understood. In particular, microstructural investigations and wear optimization studies of HMMCs are not clear. Therefore, further studies are required. The present study is aimed at fabricating and mechanical and wear characterizing and microstructure investigating of Silicon Carbide (SiC) and Graphite (Gr) added in Aluminum (Al) alloy Al6061 HMMCs. The addition of SiC particles was in the range from 0 to 9 weight percentage (wt.%) in steps of 3, along with the addition of 1 wt.% Gr in powder form. The presence of alloying elements in the Al6061 alloy was identified using the Energy Dispersive X-Ray Analysis (EDX). The dispersion of SiC and Gr particles in the alloy was investigated using metallurgical microscope and Scanning Electron Microscopy (SEM). The gain in strength can be attributed to the growth in dislocation density. The nature of fracture was quasi-cleavage. The microstructure examination reveals the uniform dispersion of the reinforcement. Density, hardness, and Ultimate Tensile Strength values observed to be increased with increased contents of SiC reinforcement. Besides, wear studies were performed in dry sliding conditions. Optimization studies were performed to investigate the effect of parameters that affecting the wear. The sliding wear resistance was noticed to be improved concerning higher amounts of reinforcement leading to a decrease in delamination and adhesive wear. The predicted values for the wear rate have also been compared with the experimental results and good correlation is obtained

One-shot cluster-based approach for the detection of COVID–19 from chest X–ray images

Coronavirus disease (COVID-19) has infected over more than 28.3 million people around the globe and killed 913K people worldwide as of 11 September 2020. With this pandemic, to combat the spreading of COVID-19, effective testing methodologies and immediate medical treatments are much required. Chest X-rays are the widely available modalities for immediate diagnosis of COVID-19. Hence, automation of detection of COVID-19 from chest X-ray images using machine learning approaches is of greater demand. A model for detecting COVID-19 from chest X-ray images is proposed in this paper. A novel concept of cluster-based one-shot learning is introduced in this work. The introduced concept has an advantage of learning from a few samples against learning from many samples in case of deep leaning architectures. The proposed model is a multi-class classification model as it classifies images of four classes, viz., pneumonia bacterial, pneumonia virus, normal, and COVID-19. The proposed model is based on ensemble of Generalized Regression Neural Network (GRNN) and Probabilistic Neural Network (PNN) classifiers at decision level. The effectiveness of the proposed model has been demonstrated through extensive experimentation on a publicly available dataset consisting of 306 images. The proposed cluster-based one-shot learning has been found to be more effective on GRNN and PNN ensembled model to distinguish COVID-19 images from that of the other three classes. It has also been experimentally observed that the model has a superior performance over contemporary deep learning architectures. The concept of one-shot cluster-based learning is being first of its kind in literature, expected to open up several new dimensions in the field of machine learning which require further researching for various applications