40 research outputs found

    ADHESION OF BIOCOMPATIBLE TiNb COATING

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    Preparation of a coating with a high quality requires good adhesion of the film to the substrate. The paper deals with the adhesion of biocompatible TiNb coating with different base materials. Several materials such as titanium CP grade 2, titanium alloys Ti6Al4V and stainless steel AISI 316L were measured. Testing samples were made in the shape of small discs. Those samples were coated with a TiNb layer by using the PVD method (magnetron sputtering). Onto the measured layer of TiNb an assistant cylinder was stuck using a high strength epoxy adhesive E1100S. The sample with the assistant cylinder was fixed into a special fixture and the whole assembly underwent pull-off testing for adhesion. The main result of this experiment was determining the strength needed to peel the layer and morphology and size of the breakaway. As a result, we will be able to determine the best base material and conditions where the coating will be remain intact with the base material

    Interference of Field Evidence, Morphology, and DNA Analyses of Three Related Lysiphlebus Aphid Parasitoids (Hymenoptera: Braconidae: Aphidiinae)

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    This study provides evidence on integrating the morphological, field, and laboratory data, and application of the cytochrome oxidase subunit I (COI) barcoding gene to the three asexual or sexual Lysiphlebus spp., i.e., Lysiphlebus cardui (Marshall), Lysiphlebus confusus Tremblay and Eady and Lysiphlebus fabarum (Marshall) (Hymenoptera: Braconidae: Aphidiinae). New aphid-invasive plant association, Aphis fabae Scopoli (Hemipreta: Aphididae) on Impatiens glandulifera Royle, has been used in the same model area in the Czech Republic under the same sampling and rearing method for several consecutive years and throughout the season. For molecular identification of these three species, we used DNA sequences of the barcoding region of the mitochondrial COI gene. Although our results confirmed ecological and morphological differences among L. cardui, L. confusus, and L. fabarum, genetic analysis on the basis of COI mitochondrial barcoding gene does not support species status of the mentioned Lysiphlebus taxa. The level of morphological differentiation in these Lysiphlebus Forster species is in accordance with the usual species variability within subfamily Aphidiinae. However, it should be examined how appearance of asexual lineages affects the morphological or genetical variability

    Integrative taxonomy of root aphid parasitoids from the genus Paralipsis (Hymenoptera, Braconidae, Aphidiinae) with description of new species

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    Species from the genus Paralipsis are obligatory endoparasitoids of root aphids in the Palaearctic. It is known that these species are broadly distributed, parasitizing various aphid hosts and showing great biological and ecological diversity. On the other hand, this group of endoparasitoids is understudied and was thought to be represented by a single species in Europe, viz., Paralipsis enervis (Nees). However, recent description of two new species indicated the possibility of cryptic speciation and recognition of additional Paralipsis species in Europe. In this research, Paralipsis specimens collected during the last 60 years from eight European countries, as well as one sample from Morocco, were subjected to molecular and morphological characterization. Newly designed genus-specific degenerative primers successfully targeted short overlapping fragments of COI of the mitochondrial DNA. Molecular analyses showed clear separation of four independent lineages, two of which are the known species P. enervis and P. tibiator, while two new species are described here, viz., P. brachycaudi Tomanovic & Stary, sp. n. and P. rugosa Tomanovic & Stary, sp. n. No clear specialization of the taxa to a strict root aphid host has been determined. The recognized mitochondrial lineages were distinct one from another, but with a substantial within-lineage divergence rate, clearly indicating the complexity of this group of parasitoids, on which further research is required in order to clarify the factors triggering their genetic differentiation. We reviewed literature data and new records of Paralipsis enervis aphid host associations and distributions. A key for the identification of all known Paralipsis species is provided and illustrated

    APHIDIINAE (HYMENOPTERA: BRACONIDAE) OF SERBIA AND MONTENEGRO – TRITROPHIC INTERACTIONS

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    This study brings a list of original data of parasitic wasps from the subfamily Aphidiinae collected on the territory of Serbia and Montenegro associated with their aphid hosts and plants. Twenty-three genera and 122 species of Aphidiinae were identified from 204 aphid taxa occurring on 344 plant taxa. A total number of 794 parasitoid-aphid-plant associations is reported and presented alphabetically according to parasitoids classified in four tribes

    Genetic and morphological variation in sexual and asexual parasitoids of the genus Lysiphlebus - an apparent link between wing shape and reproductive mode

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    Background: Morphological divergence often increases with phylogenetic distance, thus making morphology taxonomically informative. However, transitions to asexual reproduction may complicate this relationship because asexual lineages capture and freeze parts of the phenotypic variation of the sexual populations from which they derive. Parasitoid wasps belonging to the genus Lysiphlebus Foerster (Hymenoptera: Braconidae: Aphidiinae) are composed of over 20 species that exploit over a hundred species of aphid hosts, including many important agricultural pests. Within Lysiphlebus, two genetically and morphologically well- defined species groups are recognised: the "fabarum" and the "testaceipes" groups. Yet within each group, sexual as well as asexual lineages occur, and in L. fabarum different morphs of unknown origin and status have been recognised. In this study, we selected a broad sample of specimens from the genus Lysiphlebus to explore the relationship between genetic divergence, reproductive mode and morphological variation in wing size and shape (quantified by geometric morphometrics). Results: The analyses of mitochondrial and nuclear gene sequences revealed a clear separation between the "testaceipes" and "fabarum" groups of Lysiphlebus, as well as three well-defined phylogenetic lineages within the "fabarum" species group and two lineages within the "testaceipes" group. Divergence in wing shape was concordant with the deep split between the "testaceipes" and "fabarum" species groups, but within groups no clear association between genetic divergence and wing shape variation was observed. On the other hand, we found significant and consistent differences in the shape of the wing between sexual and asexual lineages, even when they were closely related. Conclusions: Mapping wing shape data onto an independently derived molecular phylogeny of Lysiphlebus revealed an association between genetic and morphological divergence only for the deepest phylogenetic split. In more recently diverged taxa, much of the variation in wing shape was explained by differences between sexual and asexual lineages, suggesting a mechanistic link between wing shape and reproductive mode in these parasitoid wasps

    Analysis of arterial intimal hyperplasia: review and hypothesis

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    which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Despite a prodigious investment of funds, we cannot treat or prevent arteriosclerosis and restenosis, particularly its major pathology, arterial intimal hyperplasia. A cornerstone question lies behind all approaches to the disease: what causes the pathology? Hypothesis: I argue that the question itself is misplaced because it implies that intimal hyperplasia is a novel pathological phenomenon caused by new mechanisms. A simple inquiry into arterial morphology shows the opposite is true. The normal multi-layer cellular organization of the tunica intima is identical to that of diseased hyperplasia; it is the standard arterial system design in all placentals at least as large as rabbits, including humans. Formed initially as one-layer endothelium lining, this phenotype can either be maintained or differentiate into a normal multi-layer cellular lining, so striking in its resemblance to diseased hyperplasia that we have to name it "benign intimal hyperplasia". However, normal or "benign " intimal hyperplasia, although microscopically identical to pathology, is a controllable phenotype that rarely compromises blood supply. It is remarkable that each human heart has coronary arteries in which a single-layer endothelium differentiates earl

    ADHESION OF BIOCOMPATIBLE TiNb COATING

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    Preparation of a coating with a high quality requires good adhesion of the film to the substrate. The paper deals with the adhesion of biocompatible TiNb coating with different base materials. Several materials such as titanium CP grade 2, titanium alloys Ti6Al4V and stainless steel AISI 316L were measured. Testing samples were made in the shape of small discs. Those samples were coated with a TiNb layer by using the PVD method (magnetron sputtering). Onto the measured layer of TiNb an assistant cylinder was stuck using a high strength epoxy adhesive E1100S. The sample with the assistant cylinder was fixed into a special fixture and the whole assembly underwent pull-off testing for adhesion. The main result of this experiment was determining the strength needed to peel the layer and morphology and size of the breakaway. As a result, we will be able to determine the best base material and conditions where the coating will be remain intact with the base material

    Parasitoids (Hymenoptera: Braconidae: Aphidiinae) Attacking Aphids Feeding on Solanaceae and Cucurbitaceae Crops in Southeastern Europe: Aphidiine-Aphid-Plant Associations and Key

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    Original information oil aphidiine braconids attacking aphids feeding on Solanaceae (i.e., Capsicum annuum L., Lycium europaeum, L., Lycopersicon esculentum Miller, Solanum spp.) and Cucurbitaceae (i.e., Citrullus vulgaris Schrad., Cucumis spp., Cucurbita pepo L.) plants in southeastern Europe is presented. A total of 13 species are keyed and illustrated with scanning electron micrographs, microscope micrographs and line drawings. The aphidiines presented in this work have been identified from nine aphid taxa. Two hundred four aphidiine-aphid-plant associations are presented, 176 of which are new. The results are discussed in relation to over-all parasitoid-aphid-plant associations in the area

    Lysiphlebus orientalis (Hymenoptera, Braconidae), a new invasive aphid parasitoid in Europe - evidence from molecular markers

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    We report the occurrence of Lysiphlebus orientalis in Serbia, an aphid parasitoid from the Far East that is new to Europe and has the potential to become invasive. Our finding based on morphological characters is confirmed by analyses of mitochondrial cytochrome oxidase subunit I sequences. An increase in number and an expansion of the host range were observed during field studies over the past two years, and it is determined that the current host range encompasses nine aphid hosts on 12 different host plants, forming 13 tri-trophic associations. A host range determined for European populations of L. orientalis appears wider compared with that in its Far Eastern native habitats where Aphis glycines Mats. is the sole known host. Moreover, it overlaps considerably with the host ranges of European parasitoids that play an important role in the natural control of pest aphids
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