40 research outputs found

    Protective effect of ultrathin alumina film against diffusion of iron into carbon fiber during growth of carbon nanotubes for hierarchical composites investigated by ptychographic X-ray computed tomography

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    Composite materials based on carbon fiber (CF) are prone to failure at the fiber-matrix interface upon compression or stress transverse to the fiber axis. The direct growth of carbon nanotubes on CF constitutes a novel approach to enhance the mechanical properties of the interface. However, the challenge is that, during the growth, tensile properties of the fiber are altered due to the diffusion effect of iron nanoparticles used in the process, leading to CF surface defect formation. In this work, we deliver and discuss an analysis methodology on ptychographic X-ray computed tomography (PXCT) images in order to assess the iron nanoparticle abundance within CFs. PXCT provides 50 nm - resolved 3D electron density maps of the CFs. We evidence the protective effect of an ultrathin alumina film against iron infiltration into CF during the CNT growth. This method potentially allows to evaluate the efficiency of other diffusion-minimizing approaches. The conclusions of the PXCT examination are validated by energy-dispersive X-ray spectroscopy and scanning transmission electron microscopy carried out on thin sample slices cut with a focused ion beam. The results provide a new insight into the mechanical performance of CFs and therefore constitute valuable knowledge for the development of hierarchical composites

    Analysis of immunohistochemical expression of proinflammatory cytokines (IL-1α, IL-6, and TNF-α) in gallbladder mucosa: comparative study in acute and chronic calculous cholecystitis

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    Background: Several studies have shown increased serum levels of proinflammatory cytokines (IL-1α, IL-6, and TNF-α) in patients with cholelithiasis. The local expression of the proteins involved in pathogenesis of the disease is poorly recognised. Materials and methods: The authors examined immunohistochemically (IHC) the expression status of IL-1α, IL-6, and TNF-α in gallbladder mucosa of the patients with cholelithiasis as related to acute (ACC) and chronic (CCC) types of cholecystitis. Proinflammatory cytokines were quantitatively evaluated in gallbladder mucosa (epithelium and lamina propria) in ACC (n = 16) and CCC (n = 55) groups using modern spatial visualisation technique. Results: Quantitative analysis of IHC signals showed no significant differences in IL-1α and IL-6, and immunoexpression in patients with ACC and CCC. A significantly greater IHC expression of TNF-α was detected in CCC as compared with ACC group. In either of the patient groups immunoexpression of IL-1α and of TNF-α was significantly higher than that of IL-6. Immunoexpression of TNF-α was significantly higher than that of IL-1α only in CCC group. A positive correlation was disclosed between IHC expression of IL-1α and body mass index in CCC group. IHC expression of TNF-α correlated positively with expression of CD68 molecule (histiocytic marker), number of leukocytes in blood and higher grading of gallbladder wall in ACC group. Conclusions: A more pronounced IHC expression of TNF-α and IL-1α than IL-6 in both types of cholecystitis may suggest the role of these cytokines in pathogenesis of cholelithiasis. IHC expression of TNF- α shows better correlation with clinical/laboratory data in acute cholecystitis, and its quantitative prevalence over the remaining cytokines points to the role of the TNF-α in maintenance of inflammation in the course of cholelithiasis

    Pericentromeric location of the telomeric DNA sequences on the European grayling chromosomes

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    The chromosomal characteristics, locations and variations of the C-band positive heterochromatin and telomeric DNA sequences were studied in the European grayling karyotype (Thymallus thymallus, Salmonidae) using conventional C-banding, endonucleases digestion banding, silver nitrate (AgNO3), chromomycin A(3) and 4',6-diamidino-2-phenylindole staining techniques as well as fluorescence in situ hybridization (FISH) and primed in situ labelling. Original data on the chromosomal distribution of segments resistant to AluI restriction endonuclease and identification of the C-banded heterochromatin presented here have been used to characterize the grayling karyotype polymorphism. Structural and length polymorphism of the chromosome 21 showing a conspicuous heterochromatin block adjacent to the centromere seems to be the result of the deletion and inversion. Two pairs of nuclear organizer regions (NOR)-bearing chromosomes were found to be polymorphic in size and displaying several distinct forms. FISH with telomeric peptide nucleic acid probe enabled recognition of the conservative telomeric DNA sequences. The karyotype of the thymallid fish is thought to experienced numerous pericentric inversions and internal telomeric sites (ITSs) observed at the pericentromeric regions of the six European grayling metacentric chromosomes are likely relics of the these rearrangements. None of the ITS sites matched either chromosome 21 or NOR bearing chromosomes.University of Warmia and Mazury in Olsztyn, Poland (0804.0809)info:eu-repo/semantics/publishedVersio

    Population genomics of post-glacial western Eurasia.

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    Western Eurasia witnessed several large-scale human migrations during the Holocene <sup>1-5</sup> . Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations

    Publisher Correction: Population genomics of post-glacial western Eurasia.

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    Characteristics of biosorbent Trichoderma viride in Fe (III) biosorption process from water solution

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    Wykonano analizę widm FTIR (Fourier Transform Infrared Spectroscopy) złoża biosorbentu stosowanego w procesie biosorpcyjnego usuwania jonów żelaza z roztworu wodnego. Zastosowano złoże szczepu grzyba pleśniowego Trichoderma viride. Widma podczerwieni wykonano zarówno dla wodorowej jak i sodowej formy grzyba pleśniowego. Dodatkowo przeanalizowano zmiany struktury powierzchni grzyba pleśniowego po procesie biosorpcji żelaza z roztworów wodnych.The FTIR analysis (Fourier Transform Infrared Spectroscopy) of biosorbent bed used for iron removal from water solution in biosorption process was performed. Fungus Trichoderma viride was used as the biosorption bed. Infrared spectra for both hydrogen and sodium form are presented and analyzed. Additionally, a change of fungus surface structure after biosorption is described

    Hydrocarbons on sea water: steady-state spreading signatures determined by an optical method

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    The spreading properties of several hydrocarbons (vegetable, engine, gear and crude oils) on distilled and artificial sea water were determined under laboratory conditions using a novel optical method. With the aid of Langmuir’s equation, the geometrical signatures of a discrete lens of each hydrocarbon droplet floating on a water tank served to calculate the entering E (31.30–94.18 mN m−1) and spreading S (−3.50 to −57.49 mN m−1) coefficients, and equilibrium thicknesses t∞ (0.20–1.25 cm). They appeared to be in agreement with the values derived from direct interfacial tension measurements (Wilhelmy plate and stalagmometer methods). Empirical relations of the normalized lens radius rL/rdrop and S on the water surface tension γAW were postulated as being of significant value in oil spill assessment studies at sea. The parameters obtained together with the surface properties of a natural surfactant-containing water body represent the principal input data required for modelling the spreading of a surface-tension-gradient-driven oil spill at sea
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