776 research outputs found
Bookbinding Information on the Web: Breaking the Circle, from Pixels to Linked Open Data
The “Digital Heritage: Spotlight on Europe” column examines technological advances internal and external to cultural institutions. The digital shift changed radically how cultural heritage is made, disseminated, distributed, accessed, consumed, and monetized. One of the most important revolutions is that the user's role changed dramatically, shifting from passive observers to active participants and content producers with many new and exciting opportunities for engagement, creative use, and access. The strength of the column is its broad, international focus, and contributors are encouraged to explore issues and recent advances in digital heritage theories, methodologies, standards relevant to the European region, as well as the larger, global audience. Interested authors are invited to submit proposals and articles to the column editor at [email protected]. Please include “ILLR submission” in the subject line of the e-mail.
Research on historical bookbindings has suffered both for reasons internal to the discipline and external. Internally, the almost exclusive focus on decorated bindings has hindered the development of methodologies to describe any kind of bookbinding, which externally, in turn, has impeded cataloguers from describing these objects—their structures in particular—creating a vicious circle in the production of resources on bookbindings. After having analyzed the state of the art of bookbinding resources, we propose that the implementation of semantic web technologies may offer a way to break the bookbinding resource vicious circle
Interactions of Engineered Nanoparticles with Organs Protected by Internal Biological Barriers
Engineered nanomaterials may exert adverse effects on human health which, in turn, may be linked
to their propensity to cross biological barriers in the body. Here, we will discuss available evidence
based on in vivo studies for interactions of commercially relevant nanoparticles with critical internal
barriers. The internal barriers at focus of this review are the blood-brain barrier (BBB), protecting
the brain, the blood-testis barrier (BTB), protecting the male germ line, and the placenta, protecting
the developing fetus. The route of exposure (pulmonary, gastrointestinal, intravenous,
intraperitoneal, dermal), and the portal of entry of nanoparticles into the body, is of critical
importance. Different physico-chemical properties, not only size, may determine the ability of
nanoparticles to breach biological barriers; the situation is further compounded by the formation of
a so-called corona of biomolecules on the surface of nanoparticles, the composition of which may
vary depending on the route of exposure and the “history” of the nanoparticles as they translocate
from one biological compartment to another. The relevance of nanoparticle interactions with
internal biological barriers for their impact on the organs protected by these barriers is discussed
Detection of new eruptions in the Magellanic Clouds LBVs R 40 and R 110
We performed a spectroscopic and photometric analysis to study new eruptions
in two luminous blue variables (LBVs) in the Magellanic Clouds. We detected a
strong new eruption in the LBV R40 that reached in 2016, which is
around mag brighter than the minimum registered in 1985. During this new
eruption, the star changed from an A-type to a late F-type spectrum. Based on
photometric and spectroscopic empirical calibrations and synthetic spectral
modeling, we determine that R\,40 reached ~K
during this new eruption. This object is thereby probably one of the coolest
identified LBVs. We could also identify an enrichment of nitrogen and r- and
s-process elements. We detected a weak eruption in the LBV R 110 with a maximum
of mag in 2011, that is, around mag brighter than in the
quiescent phase. On the other hand, this new eruption is about mag
fainter than the first eruption detected in 1990, but the temperature did not
decrease below 8500 K. Spitzer spectra show indications of cool dust in the
circumstellar environment of both stars, but no hot or warm dust was present,
except by the probable presence of PAHs in R\,110. We also discuss a possible
post-red supergiant nature for both stars
Mode I fatigue limit of notched structures: A deeper insight into Finite Fracture Mechanics
In the present contribution, the coupled stress-energy criterion of Finite Fracture Mechanics (FFM) is applied to assess the fatigue limit of structures weakened by sharp V- and U-notches and subjected to mode I loading conditions. The FFM is a critical-distance-based approach whose implementation requires the knowledge of two material properties, namely the plain material fatigue limit and the threshold value of the stress intensity factor (SIF) range for the fatigue crack growth of long cracks. However, the FFM critical distance is a structural parameter, being a function not only of the material but also of the geometry of the notched component. Experimental notch fatigue results taken from the literature and referred to a variety of materials and geometrical configurations are compared with FFM theoretical estimations, obtained through simple semi-analytical relationships. The case of semi-circular edge notches is also dealt with
Three-dimensional effects on cracked discs and plates under nominal Mode III loading
The existence of three-dimensional effects at cracks has been known for many years, but understanding has been limited, and for some situations still is. Understanding improved when the existence of corner point singularities and their implications became known. Increasingly powerful computers made it possible to investigate three-dimensional effects numerically in detail. Despite increased understanding, threedimensional effects are sometimes ignored in situations where they may be important. The purpose of the present contribution is to review the study carried out by the same authors in some recent investigations, in which a coupled fracture mode generated by anti-plane loading of a straight through-the-thickness crack in linear elastic discs and plates has been analysed by means of accurate 3D finite element (FE) models. The results obtained from the highly accurate finite element analyses have improved understanding of the behaviour of through cracked components under anti-plane loading. The influence of plate bending is increasingly important as the thickness decreases. It appears that a new field parameter, probably a singularity, is needed to describe the stresses at the free surfaces. Discussion on whether KIII tends to zero or infinity as a corner point is approached is futile because KIII is meaningless at a corner point. The intensity of the local stress and strain state through the thickness of the cracked components has been evaluated by using the strain energy density (SED) averaged over a control volume embracing the crack tip. The SED has been considered as a parameter able to control fracture in some previous contributions and can easily take into account also coupled three-dimensional effects. Calculation of the SED shows that the position of the maximum SED in the discs case is a function of the thickness. In the plates case instead the position of the maximum SED is independent of plate thickness, contrary to disc results
Physico-Chemical Properties Mediating Reproductive and Developmental Toxicity of Engineered Nanomaterials
With the increasing production of engineered nanomaterials (ENMs) exploited in many consumer products, a wider number of people is expected to be exposed to such materials in the near future, both in occupational and environmentalsettings. This has raised concerns about the possible implications on public health. In particular, very recently the scientific community has focused on the effect that ENMs might exert on the reproductive apparatus and on embryonic development. Indications that ENMs might have adverse effects on cells of the germ line and on the developing embryos have been reported. In the present minireview we will perform a critical analysis of the published work on reproductive and developmental toxicity of the most commonly used nanoparticles with a major focus on mammalian models. We will place emphasis on the main
physico-chemical characteristics that can affect NP behaviour in biological systems, i.e. presence of contaminants and nanoparticle destabilization, size,
dosage, presence of functional groups, influence of the solvent used for their suspension in biological media, aggregation/agglomeration, intrinsic chemical
composition and protein corona/opsonisation. The importance of this specific field of nanotoxicology is documented by the rapidly increasing number of
published papers registered in the last three years, which might be a consequence of the growing concerns on the possible interference of ENMs with reproductive ability and pregnancy outcome, in a time in which reproductive age has increased
and the possibility to bear children appears reduced
Coupled fracture modes under anti-plane loading
The linear elastic analysis of homogeneous, isotropic cracked bodies is a Twentieth Century development. It was recognised that the crack tip stress field is a singularity, but it was not until the introduction of the essentially two dimensional stress intensity factor concept in 1957 that widespread application to practical engineering problems became possible. The existence of three dimensional corner point effects in the vicinity of a corner point where a crack front intersects a free surface was investigated in the late 1970s: it was found that modes II and III cannot exist in isolation. The existence of one of these modes always induces the other. An approximate solution for corner point singularities by Bažant and Estenssoro explained some features of corner point effects but there were various paradoxes and inconsistencies. In an attempt to explain these a study was carried out on the coupled in-plane fracture mode induced by a nominal anti-plane (mode III) loading applied to plates and discs weakened by a straight crack. The results derived from a large bulk of finite element models showed clearly that Bažant and Estenssoro's analysis is incomplete. Some of the results of the study are summarised, together with some recent results for a disc under in-plane shear loading. On the basis of these results, and a mathematical argument, the results suggest that the stress field in the vicinity of a corner point is the sum of two singularities: one due to stress intensity factors and the other due to an as yet undetermined corner point singularity
Errata (per oculos) corrige: Visual identification of meaningless data in database records of bookbinding structures
some recent criteria for brittle fracture prediction under in plane shear loading
Abstract: Different criteria are available in the literature to assess the fracture behaviour of sharp V-notches. A typical and well-known criterion is based on the application of the notch stress intensity factors (NSIFs), which are able to quantify the intensity of the stress fields ahead of the notch tip. This work considers two recent energy-based criteria applied here to sharp V-notches. The first criterion is based on the averaged value of the strain energy density (SED), while the second one called Finite Fracture Mechanics (FFM) criterion is available under two different formulations: that by Leguillon et al. and that by Carpinteri et al. Considering the averaged SED criterion, a new expression for estimating the control radius R c under pure Mode II loading is proposed and compared with the sound expression valid under pure Mode I loading. With reference to pure Mode II loading the critical NSIF at failure can be expressed as a function of the V-notch opening angle. By adopting the three criteria considered here the expressions for the NSIFs are derived and compared. After all, the approaches are employed considering sharp V-notched brittle components under in-plane shear loading, in order to investigate the capability of each approach for the fracture assessment. With this aim a bulk of experimental data taken from the literature is used for the comparison
Crosswalking or jaywalking? the visualization of linked scientific and humanities data
A critical aspect of shared data is using an easily accessible interface that is interoperable across a wide range of heritage institutions. An innovative approach to heritage science, where data is generated about the materiality of heritage materials, is linking this data back to a visual rendering of the heritage material to begin a process of linked data and integration between science and humanities. Using the International Image Interoperability Framework (IIIF), the shared canvas data model is being expanded for integrating linked scientific analyses to this digital surrogate. There are challenges with this approach for spectral imaging data due to the additional required layers of metadata in the spectral, spatial and temporal modes, which need to be consistent, and persistent, across sets of canvases
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