Influence of Technology of Hot Forming of Plates from Aluminum Alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu on Resistance to Fatigue Fracture

Introduction. One of the primary objectives in the development of promising aircraft products is to reduce the weight of the aircraft structure. This problem can be solved by applying new low density materials such as aluminum alloys alloyed with lithium (for example, Al-Cu-Li-Zn) in the design of parts. The use of these materials in aircraft construction is limited by the processing technology, which must be such as not to damage the material and not reduce its strength properties. Such technologies include processing by pressure with heating, when creep processes are activated and the material passes into a state close to superplasticity. The purpose of the work: assessment of the effect of pressure shaping of aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu in creep mode on strength. The paper investigates the influence of the technology of pressure shaping of aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu on the resistance to fatigue failure. The work uses a method that allows to determine the ultimate stresses using diagrams of the accumulation of irreversible deformations; method of forming thick plates (40 mm) in the creep mode. The previously selected optimum temperatures for forming the plates are used. A non-contact coordinate measuring system is used to perform surface inspection after shaping. Fractography of the fracture of samples of alloy Al-Cu-Li-Zn and Al-Zn-Mg-Cu after fatigue failure is performed. Mathematical modeling of the deformation process of plates in creep mode is carried out in the MSC.Marc package. As a result, a conservative evaluation of the endurance limit for aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu is obtained. The shaping of thick plates in the creep mode is carried out. More than 80% of the board surface is formed with a deviation of less than 1 mm from the target size. Fatigue tests of samples made of molded panels of alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu are carried out, fatigue curves are plotted. The fractography of the surface of the fatigue fracture showed the presence of oxides in the samples of alloy Al-Cu-Li-Zn, in contrast to alloy Al-Zn-Mg-Cu. The results of fatigue tests are discussed, showing that the characteristics of the technological process of shaping and heat treatment do not deteriorate the fatigue properties of the investigated alloys. Comparative tests show that alloy Al-Cu-Li-Zn has higher fatigue characteristics. Mathematical modeling show that the use of the Boyle-Norton steady-state creep law is not enough to describe the process of plate forming. The necessity of setting the inverse problem of creep age forming is noted, where the coordinates of the punches of the loading device should act as boundary conditions.

Material Inspirations

This book is a study of the relationship between matter and idea that shaped the nineteenth-century culture of art, and that in turn determined the course of still-current accounts of art’s nature and value. Drawing on recent scholarship on the history of art and its institutions, Material Inspirations places cultural developments such as the emergence of new sites for exhibition and the astonishing proliferation of printed reproductions alongside a wide range of texts including novels, poems, travel guidebooks, compendia of antiquities, and especially the great line of critical writing that emerged in the period. The study aims to vivify a dynamic era, too often seen as static and unchanging, by emphasizing the transformations taking place throughout the period in precisely those areas that have appeared to promise little more than repetition or continuity: collection, exhibition, and reproduction. The book culminates with the two great critics of the period, John Ruskin and Walter Pater, but it also includes close analysis of other prose writers, as well as poets and novelists ranging from William Blake to Robert Browning, George Eliot to Henry James. Significant developments addressed include the vogue for the representation of Old Masters in the first half of the century, ongoing innovations in the creation and diffusion of reproductions, and the emergence of the field of art history itself. At the heart of each of these the book identifies a material pressure shaping concepts, texts, and works of art.

Multi-species annotation of transcriptome and chromatin structure in domesticated animals

Background Comparative genomics studies are central in identifying the coding and non-coding elements associated with complex traits, and the functional annotation of genomes is a critical step to decipher the genotype-to-phenotype relationships in livestock animals. As part of the Functional Annotation of Animal Genomes (FAANG) action, the FR-AgENCODE project aimed to create reference functional maps of domesticated animals by profiling the landscape of transcription (RNA-seq), chromatin accessibility (ATAC-seq) and conformation (Hi-C) in species representing ruminants (cattle, goat), monogastrics (pig) and birds (chicken), using three target samples related to metabolism (liver) and immunity (CD4+ and CD8+ T cells). Results RNA-seq assays considerably extended the available catalog of annotated transcripts and identified differentially expressed genes with unknown function, including new syntenic lncRNAs. ATAC-seq highlighted an enrichment for transcription factor binding sites in differentially accessible regions of the chromatin. Comparative analyses revealed a core set of conserved regulatory regions across species. Topologically associating domains (TADs) and epigenetic A/B compartments annotated from Hi-C data were consistent with RNA-seq and ATAC-seq data. Multi-species comparisons showed that conserved TAD boundaries had stronger insulation properties than species-specific ones and that the genomic distribution of orthologous genes in A/B compartments was significantly conserved across species. Conclusions We report the first multi-species and multi-assay genome annotation results obtained by a FAANG project. Beyond the generation of reference annotations and the confirmation of previous findings on model animals, the integrative analysis of data from multiple assays and species sheds a new light on the multi-scale selective pressure shaping genome organization from birds to mammals. Overall, these results emphasize the value of FAANG for research on domesticated animals and reinforces the importance of future meta-analyses of the reference datasets being generated by this community on different species.

Sender and receiver experience alters the response of fish to disturbance cues

Predation is a pervasive selection pressure, shaping morphological, physiological, and behavioral phenotypes of prey species. Recent studies have begun to examine how the effects of individual experience with predation risk shapes the use of publicly available risk assessment cues. Here, we investigated the effects of prior predation risk experience on disturbance cue production and use by Trinidadian guppies Poecilia reticulata under laboratory conditions. In our first experiment, we demonstrate that the response of guppies from a high predation population (Lopinot River) was dependent upon the source of disturbance cue senders (high vs. low predation populations). However, guppies collected from a low predation site (Upper Aripo River) exhibited similar responses to disturbance cues, regardless of the sender population. In our second experiment, we used laboratory strain guppies exposed to high versus low background risk conditions. Our results show an analogous response patterns as shown for our first experiment. Guppies exposed to high background risk conditions exhibited stronger responses to the disturbance cues collected from senders exposed to high (vs. low) risk conditions and guppies exposed to low risk conditions were not influenced by sender experience. Combined, our results suggest that experience with background predation risk significantly impacts both the production of and response to disturbance cues in guppies.

Study on Producing Sand-Lime Bricks with Iron Ore Tailings and Phosphogypsum and other Solid Wastes

The paper studied preparing sand-lime bricks by pressure shaping and nature curing, discussed the stimulation effect of compound activators composed of phosphogypsum and lime. The result shows that: when the proportions of raw materials are as follows: 10~15% weight content is iron ore tailings, 3% is phosphogypsum, 5% lime, 5% cement, 40~45% low quality fly ash, and 22~37% chips, the strength of sand-lime bricks produced gets its highest. XRD and SEM are used to characterize its mineral composition and microstructure. The paper also discussed the relationship between structure and performance inside the bricks, and its hydration mechanism.

Susceptibility of Intact Germinating Arabidopsis thaliana to Human Fungal Pathogens Cryptococcus neoformans and C. gattii

ABSTRACTThe fungusCryptococcuscontributes a large global burden of infectious death in both HIV-infected and healthy individuals. AsCryptococcusis an opportunistic pathogen, much of the evolutionary pressure shaping virulence occurs in environments in contact with plants and soil. The present studies investigated inoculation of intact seeds of the common weedArabidopsis thalianawith fungal cells over a 21-day period.C. gattiiwas the more virulent plant pathogen, resulting in disrupted germination as well as increased stem lodging, fungal burden, and plant tissue colocalization.C. neoformanswas a less virulent plant pathogen but exhibited prolonged tissue residence within the cuticle and vascular spaces. Arabidopsis mutants of thePRN1gene, which is involved in abiotic and biotic signaling affecting phenylalanine-derived flavonoids, showed altered susceptibility to cryptoccocal infections, suggesting roles for this pathway in cryptococcal defense. The fungal virulence factor laccase was also implicated in plant pathogenesis, as a cryptococcallac1Δ strain was less virulent than wild-type fungi and was unable to colonize seedlings. In conclusion, these studies expand knowledge concerning the ecological niche ofCryptococcusby demonstrating the pathogenic capacity of the anamorphic form of cryptococcal cells against healthy seedlings under physiologically relevant conditions. In addition, an important role of laccase in plant as well as human virulence may suggest mechanisms for laccase retention and optimization during evolution of this fungal pathogen.