323,000 research outputs found
DEVELOPMENT OF METAL-DIAMOND COMPOSITES FOR LIGHT-WEIGHT ARMOUR
No full textMetal Diamond Composites (Me-CD) are a new class of metal matrix composites that are exciting the interest of designers and engineers because of their unique combination of physical, thermal, electrical and mechanical properties. In general, due to the high volume fraction of diamonds inside the matrix, the mechanical behavior of such materials is always brittle with low level of fracture stress and strain. However, with advanced innovations in the sintering processes, it is possible to obtain composite materials with a good level of strength and toughness even in high strain-rate conditions. The great advantage of these materials is the possibility to combine the high hardness and low density of diamonds with the strength and toughness of metals. This class of materials could be used in every case in which the material requirements are hardness combined with ductility and lightness: military protection devices instead of synthetic alumina or carbides are potential applications. Due to the composite nature, the strain and stress distribution in the material is quite complex and, as a consequence, the mechanical behavior is different from a homogeneous one. The elastic properties, which are fundamental in case of wave propagation, were calculated using the mixture law and then compared with that of other ceramic materials usually used in military protection. Preliminary impact tests were conducted using a single bar SHPB setup in order to qualitatively investigate the fracture mechanism. SEM analyses were also performed to examine the interface between diamond and aluminiu
Cytogenetic analysis of the holocentric chromosomes of the aphid Schizaphis graminum
No full textChromatin organization in the holocentric chromosomes of the aphid Schizaphis graminum has been investigated at a cytological level after C-banding, NOR, Giemsa, DAPI and CMA(3) staining. C-banding technique showed the presence of numerous C bands on the two X chromosomes both in telomeric and intercalary regions, whereas autosomes show a small number of heterochromatic bands. Contrary to the results with other aphid species, in S. graminum the C-banding pattern is peculiar to each chromosome pair, thus allowing the identification of homologues and the reliable reconstruction of a karyotype. These cytogenetic data could be useful for the identification of chromosomal rearrangement eventually occurred between different S. graminum biotypes. Moreover, silver staining and fluorescent in situ hybridization (FISH) with a 28S rDNA probe localized rDNA genes on one telomere of each X chromosome; these are the only brightly fluorescent C-positive regions revealed after CMA(3) staining, whereas all other heterochromatic bands are DAPI positive
Proof of Evolution: Leveraging blockchain mining for a cooperative execution of Genetic Algorithms
No full textProof of Work (PoW) is the consensus protocol introduced with Bitcoin, and is still one of the most used protocols, thanks to its security properties. However, it is very expensive in terms of energy consumption. For this reason, many other protocols have been designed in order to earmark part of the computations for useful tasks, or to reduce them, but few of these have the same properties of PoW.With this paper we propose a new consensus protocol for blockchains, called Proof of Evolution (PoE), that keeps the security features of PoW, and uses part of the mining computations for the execution of genetic algorithms (GAs) that some clients can submit. Moreover, PoE enables a form of cooperation among miners. During the mining process, in fact, miners have to maintain and evolve a population of solution candidates; PoE offers them the possibility of sharing their current best found solutions, that they can add to their population. This exchange seems to enhance the quality of the solutions they can achieve with the GAs in use. PoE is close to Proof of Search (PoS), which in turn extends PoW in order to solve optimization problems while mining. While PoS stimulates miners in submitting solutions for a problem of interest, the contribution of PoE is to encourage them to share their current best found solutions, allowing cooperation
Development and testing of novel advanced materials with very high thermal shock resistance
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A novel in vitro sperm head decondensation protocol for a rapid flow cytometric measurement of DNA content
No full textObjective: To set up a novel protocol of sperm head in vitro decondensation that obviates the problematic effect of the variable degree
of sperm chromatin packaging on DNA staining needed for flow cytometric analysis.
Design: Development of a new cytofluorimetric assay.
Setting: University laboratory.
Patient(s): Semen specimens were obtained from normospermic healthy volunteers at the Department of Life and Environmental Sciences,
Universita Politecnica delle Marche.
Intervention(s): Setup of the novel in vitro sperm head decondensation protocol; sperm were then stained and analyzed by flow cytometry
to measure DNA content.
Main Outcome Measure(s): Mean fluorescent channel, DNA content, percentage diploid sperm.
Result(s): Native nondecondensed fluorochrome-labeled sperm show significant under-staining, resulting in an underestimated Cvalue
(approximately 1.4 pg). This protocol ensures stoichiometric staining of sperm DNA, which becomes fully reachable by
fluorescent probes and makes the diploid (7.12 pg) over haploid (3.56 pg) sperm frequency quantification easier.
Conclusion(s): This study establishes a simple method for in vitro sperm head decondensation,
which allows accurate detection of the real sperm DNA conten
Cytogenetic analysis on the holocentric chromosomes of the cabbage aphid Brevicoryne brassicae.
No full textHeterochromatin and rDNA localization on the holocentric chromosomes of black bean aphid, Aphis fabae Scop. (Hemiptera: Aphididae)
No full textSex disparity and drug-induced liver injury
No full textDrug-induced liver injury (DILI) is a potentially serious clinical condition that remains a major problem for patients, physicians and those involved in the development of new drugs. Population and hospital-based studies have reported incidences of DILI varying from 1.4 to 19.1/100.000. Overall, females have a 1.5- to 1.7-fold greater risk of developing adverse drug reactions and the female/male ratio increases after the age of 49 years, suggesting a clear susceptibility of DILI after menopause. Sex differences in pharmacokinetics and pharmacodynamic, sex-specific hormonal effects or interaction with signalling molecules that can influence drug efficacy and safety and differences in abnormal immune response following drug exposure are the main probable causes of the higher vulnerability observed among female patients. A novel phenotype of autoimmune-mediated DILI following the use of check-point inhibitors in oncology and haematology has been recently described. Finally, there have been increasing reports of DILI associated with use of herbal and dietary supplements that is more frequently reported in women
Incidental finding of anti-mitochondrial antibody: a neglected entity needing reappraisal
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