1,087 research outputs found
3D Bioprinting of GelatinâXanthan Gum Composite Hydrogels for Growth of Human Skin Cells
In recent years, bioprinting has attracted much attention as a potential tool for generating complex 3D biological constructs capable of mimicking the native tissue microenvironment and promoting physiologically relevant cellâcell and cellâmatrix interactions. The aim of the present study was to develop a crosslinked 3D printable hydrogel based on biocompatible natural polymers, gelatin and xanthan gum at different percentages to be used both as a scaffold for cell growth and as a wound dressing. The CellInk Inkredible 3D printer was used for the 3D printing of hydrogels, and a glutaraldehyde solution was tested for the crosslinking process. We were able to obtain two kinds of printable hydrogels with different porosity, swelling and degradation time. Subsequently, the printed hydrogels were characterized from the point of view of biocompatibility. Our results showed that gelatin/xanthan-gum bioprinted hydrogels were biocompatible materials, as they allowed both human keratinocyte and fibroblast in vitro growth for 14 days. These two bioprintable hydrogels could be also used as a helpful dressing material
Spontaneous formation and relaxation of spin domains in antiferromagnetic spin-1 quasi-condensates
Quantum systems of many interacting particles at low temperatures generally
organize themselves into ordered phases of matter, whose nature and symmetries
are captured by an order parameter. In the simplest cases, this order parameter
is spatially uniform. For example, a system of localized spins with
ferromagnetic interactions align themselves to a common direction and build up
a macroscopic magnetization on large distances. However, non-uniform situations
also exist in nature, for instance in antiferromagnetism where the
magnetization alternates in space. The situation becomes even richer when the
spin-carrying particles are mobile, for instance in the so-called stripe phases
emerging for itinerant electrons in strongly-correlated materials.
Understanding such inhomogeneously ordered states is of central importance in
many-body physics. In this work, we study experimentally the magnetic ordering
of itinerant spin-1 bosons in inhomegeneous spin domains at nano-Kelvin
temperatures. We demonstrate that spin domains form spontaneously after a phase
separation transition, \textit{i.e.} in the absence of external magnetic force,
purely because of the antiferromagnetic interactions between the atoms.
Furthermore, we explore how the equilibrium domain configuration emerges from
an initial state prepared far-from-equilibrium.Comment: Supplementary material available as ancillary fil
LCA of Zero Valent Iron Nanoparticles Encapsulated in Algal Biomass for Polishing Treated Effluents
Research data produced within the CARIPLO IMAP and Perform Water 2030 projects were processed using the SimaPro software to carry out the Life Cycle Assessment according to ISO 14040-44 of an innovative process of treated effluents' polishing. The study aims to evaluate the integration of a microalgae culture as a side-stream process into the baseline layout of a wastewater treatment plant to remove nitrogen from the supernatant of sludge centrifugation from an environmental perspective. In particular, the investigated system focuses on using the algal biomass produced as an organic matrix for encapsulating zero-valent iron nanoparticles to be used for the final refinement of the effluent. Zero-valent iron (ZVI) is a reactive metal and an effective reducing agent. It can be used to remove organic and inorganic pollutants (e.g., chlorinated organics, pharmaceuticals, metals, textile dyestuffs). The encapsulation of ZVI by hydrothermal carbonization (HTC) in a carbonaceous matrix allows for overcoming the problems related to its lack of stability, easy aggregation, and difficulty in separating the ZVI nanoparticles from the treated solution. The case study refers to Bresso wastewater treatment plant (Milan province, Northern Italy). The environmental performances of the study were assessed following the Life Cycle Impact Assessment methods IMPACT 2002+. According to the results, the new process integration does not affect the environmental performance of the WWTP, still implying a significant improvement in the removal of metals and micropollutants. In fact, due to the ability of ZVI nanoparticles to remove organic and inorganic pollutants, the outflowing load will be significantly reduced, which will improve the environmental performance of the entire Bresso wastewater treatment plant
Micro-probing enables fine-grained mapping of neuronal populations using fMRI
The characterization of receptive field (RF) properties is fundamental to understanding the neural basis of sensory and cognitive behaviour. The combination of non-invasive imaging, such as fMRI, with biologically inspired neural modelling has enabled the estimation of population RFs directly in humans. However, current approaches require making numerous a priori assumptions, so these cannot reveal unpredicted properties, such as fragmented RFs or subpopulations. This is a critical limitation in studies on adaptation, pathology or reorganization. Here, we introduce micro-probing (MP), a technique for fine-grained and largely assumption free characterization of multiple pRFs within a voxel. It overcomes many limitations of current approaches by enabling detection of unexpected RF shapes, properties and subpopulations, by enhancing the spatial detail with which we analyze the data. MP is based on tiny, fixed-size, Gaussian models that efficiently sample the entire visual space and create fine-grained probe maps. Subsequently, we derived population receptive fields (pRFs) from these maps. We demonstrate the scope of our method through simulations and by mapping the visual fields of healthy participants and of a patient group with highly abnormal RFs due to a congenital pathway disorder. Without using specific stimuli or adapted models, MP mapped the bilateral pRFs characteristic of observers with albinism. In healthy observers, MP revealed that voxels may capture the activity of multiple subpopulations RFs that sample distinct regions of the visual field. Thus, MP provides a versatile framework to visualize, analyze and model, without restrictions, the diverse RFs of cortical subpopulations in health and disease.</p
Foveal pRF properties in the visual cortex depend on the extent of stimulated visual field
Previous studies demonstrated that alterations in functional MRI derived receptive field (pRF) properties in cortical projection zones of retinal lesions can erroneously be mistaken for cortical large-scale reorganization in response to visual system pathologies. We tested, whether such confounds are also evident in the normal cortical projection zone of the fovea for simulated peripheral visual field defects. We applied fMRI-based visual field mapping of the central visual field at 3 T in eight controls to compare the pRF properties of the central visual field of a reference condition (stimulus radius: 14°) and two conditions with simulated peripheral visual field defect, i.e., with a peripheral gray mask, stimulating only the central 7° or 4° radius. We quantified, for the cortical representation of the actually stimulated visual field, the changes in the position and size of the pRFs associated with reduced peripheral stimulation using conventional and advanced pRF modeling. We found foveal pRF-positions (â€3°) to be significantly shifted towards the periphery (p<0.05, corrected). These pRF-shifts were largest for the 4° condition [visual area (mean eccentricity shift): V1 (0.9°), V2 (0.9°), V3 (1.0°)], but also evident for the 7° condition [V1 (0.5°), V2 (0.5°), V3 (0.9°)]. Further, an overall enlargement of pRF-sizes was observed. These findings indicate the dependence of foveal pRF parameters on the spatial extent of the stimulated visual field and are likely associated with methodological biases and/or physiological mechanisms. Consequently, our results imply that, previously reported similar findings in patients with actual peripheral scotomas need to be interpreted with caution and indicate the need for adequate control conditions in investigations of visual cortex reorganization
Benign hereditary chorea and deletions outside NKX2-1 : what's the role of MBIP?
Heterozygous point mutations or deletions of the NKX2-1 gene cause benign hereditary chorea (BHC) or a various combinations of primary hypothyroidism, respiratory distress and neurological disorders. Deletions proximal to, but not encompassing, NKX2-1 have been described in few subjects with brain-lung-thyroid syndrome. We report on a three-generation Italian family, with 6 subjects presenting BHC and harboring a genomic deletion adjacent to NKX2-1 and including the gene MBIP, recently proposed to be relevant for the pathogenesis of brain-lung-thyroid syndrome. We observed a clear reduction of NKX2-1 transcript levels in fibroblasts from our patients compared to controls; this finding suggests that MBIP deletion affects NKX2-1 expression, mimicking haploinsufficiency caused by classical NKX2-1 related mutations
Impact of Nutritional Stress on Honeybee Gut Microbiota, Immunity, and Nosema ceranae Infection
Honeybees are important pollinators, having an essential role in the ecology of natural and agricultural environments. Honeybee colony losses episodes reported worldwide and have been associated with different pests and pathogens, pesticide exposure, and nutritional stress. This nutritional stress is related to the increase in monoculture areas which leads to a reduction of pollen availability and diversity. In this study, we examined whether nutritional stress affects honeybee gut microbiota, bee immunity, and infection by Nosema ceranae, under laboratory conditions. Consumption of Eucalyptus grandis pollen was used as a nutritionally poor-quality diet to study nutritional stress, in contraposition to the consumption of polyfloral pollen. Honeybees feed with Eucalyptus grandis pollen showed a lower abundance of Lactobacillus mellifer and Lactobacillus apis (Firm-4 and Firm-5, respectively) and Bifidobacterium spp. and a higher abundance of Bartonella apis, than honeybees fed with polyfloral pollen. Besides the impact of nutritional stress on honeybee microbiota, it also decreased the expression levels of vitellogenin and genes associated to immunity (glucose oxidase, hymenoptaecin and lysozyme). Finally, Eucalyptus grandis pollen favored the multiplication of Nosema ceranae. These results show that nutritional stress impacts the honeybee gut microbiota, having consequences on honeybee immunity and pathogen development. Those results may be useful to understand the influence of modern agriculture on honeybee health.Fil: Castelli, L.. Instituto de Investigaciones BiolĂłgicas "Clemente Estable"; UruguayFil: Branchiccela, B.. Instituto de Investigaciones BiolĂłgicas "Clemente Estable"; UruguayFil: Garrido, Paula Melisa. Universidad Nacional de Mar del Plata. Instituto de Investigaciones en ProducciĂłn, Sanidad y Ambiente - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en ProducciĂłn, Sanidad y Ambiente; ArgentinaFil: Invernizzi, Ciro. No especifĂca;Fil: Porrini, MartĂn Pablo. Universidad Nacional de Mar del Plata. Instituto de Investigaciones en ProducciĂłn, Sanidad y Ambiente - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en ProducciĂłn, Sanidad y Ambiente; ArgentinaFil: Romero, H.. No especifĂca;Fil: Santos, E.. No especifĂca;Fil: Zunino, P.. Instituto de Investigaciones BiolĂłgicas "Clemente Estable"; UruguayFil: AntĂșnez, Karina. Instituto de Investigaciones BiolĂłgicas "Clemente Estable"; Urugua
Clustering of loose groups and galaxies from the Perseus--Pisces Survey
We investigate the clustering properties of loose groups in the
Perseus--Pisces redshift Survey (PPS). Previous analyses based on CfA and SSRS
surveys led to apparently contradictory results. We investigate the source of
such discrepancies, finding satisfactory explanations for them. Furthermore, we
find a definite signal of group clustering, whose amplitude exceeds the
amplitude of galaxy clustering (,
for the most significant case; distances are
measured in \hMpc). Groups are identified with the adaptive
Friends--Of--Friends (FOF) algorithms HG (Huchra \& Geller 1982) and NW
(Nolthenius \& White 1987), systematically varying all search parameters.
Correlation strenght is especially sensitive to the sky--link (increasing
for stricter normalization ), and to the (depth \mlim of the) galaxy
data. It is only moderately dependent on the galaxy luminosity function
, while it is almost insensitive to the redshift--link (both to
the normalization and to the scaling recipes HG or NW).Comment: 28 pages (LaTeX aasms4 style) + 5 Postscript figures ; ApJ submitted
on May 4th, 1996; group catalogs available upon request
([email protected]
Strategic communication and the entrepreneurial role of the corporate communication officer
Considering the recent evolution of the communication/PR profession in large
organizations both private and public, many scholars agree that a process of
institutionalization is occurring. In other words, communicationâs importance
has been growing, reaching in recent years a strategic position as a lever for
companiesâ governance.
A first objective of this chapter is to describe, looking at management and
communication/PR literature, how and to what extent communication has
become strategic. The main hypothesis is that communication has become
strategic within companiesâ governance in order to help each organization
to develop consistently â mainly in terms of values â within its environment.
A second objective is to describe, looking at the entrepreneurial organization
theory and communication/PR literature, another side of the strategic
evolution of communication, which is to help each organization to develop â
mainly in terms of services, products and reputation â as a different, or preferably
unique, entity as compared to the other organizations.
The evolution of the strategic contribution of communication/PR within
organizationsâ decision-making has a strong impact on the role that corporate
communication officers (CCOs) play in organizations both on the isomorphic
and on the entrepreneurialâinnovative sides of the communicational activity
they carry out to support the evolution of their organizations
- âŠ