Necrotizing enterocolitis (NEC) is an idiopathic, inflammatory bowel necrosis of premature infants. Clinical studies have linked NEC with antecedent red blood cell (RBC) transfusions, but the ...underlying mechanisms are unclear. Here we report a neonatal murine model to investigate this association. C57BL/6 mouse pups rendered anemic by timed phlebotomy and then given RBC transfusions develop NEC-like intestinal injury with prominent necrosis, inflammation, and submucosal edema/separation of the lamina propria in the ileocecal region and colon within 12-24 h. The anemic intestine is infiltrated by inflammatory macrophages, which are activated in situ by RBC transfusions via a Toll-like receptor (TLR)-4-mediated mechanism and cause bowel injury. Chelation of RBC degradation products with haptoglobin, absence of TLR4, macrophage depletion, and inhibition of macrophage activation is protective. Intestinal injury worsens with increasing severity and the duration of anemia prior to transfusion, indicating a need for the re-evaluation of current transfusion guidelines for premature infants.
•Effectiveness of TRM in repairing damaged masonry walls under in-plane cyclic loads.•Three full scale masonry walls have been constructed, repaired, reinforced and re-tested.•The higher ductility ...associated with TRM was observed in the cumulative energy loss.•TRM reinforcement could guarantee the structural stability.•TRM layers modified the stiffness variations, strength and the cracking pattern.
Masonry walls exhibit low tensile strength and high material heterogeneity, which makes them especially vulnerable against cyclic loading conditions, such as those typical in earthquakes. This paper presents the experimental results obtained from tests on three masonry walls reinforced with textile reinforced mortar (TRM) materials subjected to in-plane cyclic loading. These full-scale masonry walls were tested in the LARGE laboratory at the University of Alicante (Alicante, Spain). The walls had been built using a traditional construction technique, with solid clay bricks layered with lime mortar. One specimen was tested and damaged by in-plane cyclic loading and was subsequently strengthened by a vertical layer of TRM with an overlapping of 200 mm. It was then tested again until failure in a second test. In addition, another undamaged specimen had been previously reinforced with the same TRM technique and tested until failure, thus providing a third test. A network of sensors and digital image correlation systems were used to monitor displacements and crack patterns. The comparison between these experimental results made it possible to assess the effectiveness of TRM in restoring the structural integrity of damaged masonry walls and almost doubling their load-bearing capacity under cyclic loads. Conclusions obtained here provide valuable information to the scientific community, architects and structural engineers about the strengthening and repair of severely damaged masonry walls.
•Mechanical behavior of TRM specimens under high temperature is investigated.•Four different TRM systems have been analyzed.•The maximum temperature reached has been 600 °C using an electrical ...oven.•Specimens previously damaged by high temperature have been tested experimentally.•TRM systems are strongly degraded from 400 °C, and useless for 600 °C.
Although one of the main advantages of Textile Reinforced Mortars (TRM) is their non-combustible character, their behavior against fire or high temperatures has not been sufficiently studied at present. This work analyzes the behavior of different commercial systems containing inorganic mortars and fabric reinforcements based on glass, carbon and basalt fibers, subjected to different temperature levels. To characterize the mechanical response of the different systems, non-destructive tests have been carried out to determine the dynamic modulus of elasticity of the different materials, and subsequent destructive tests to determine their strength and stress-strain relationship. For this purpose, the TRM coupons have been subjected to uniaxial tensile tests and the deformations have been monitored using LVDT (Linear Variable Displacement Transducer) sensors and DIC (Digital Image Correlation), in order to evaluate cracking patterns and failure modes. The results show, in general terms, that the mechanical capacity of these materials is seriously compromised at temperatures in the order of 400 to 600 °C, which can easily be reached during a fire inside a building. Therefore, it can be concluded that although these systems are erroneously perceived as fire resistant in many cases, they may require additional protection depending on the specific use for which they are intended.
This study presents a novel methodology for the remote monitoring of aerosol
components over large spatial and temporal domains. The concept is realized
within the GRASP (Generalized Retrieval of ...Aerosol and Surface Properties)
algorithm to directly infer aerosol components from the measured radiances.
The observed aerosols are assumed to be mixtures of hydrated soluble
particles embedded with black carbon, brown carbon, iron oxide, and other
(non-absorbing) insoluble inclusions. The complex refractive indices of the
dry components are fixed a priori (although the refractive index of the
soluble host is allowed to vary with hydration), and the complex refractive
indices of the mixture are computed using mixing rules. The volume fractions
of these components are derived along with the size distribution and the
fraction of spherical particles, as well as the spectral surface reflectance in
cases when the satellite data are inverted. The retrieval is implemented as a
statistically optimized fit in a continuous space of solutions. This
contrasts with most conventional approaches in which the type of aerosol is
either associated with a pre-assumed aerosol model that is included in a set
of look-up tables, or determined from the analysis of the retrieved aerosol
optical parameters (e.g., single scattering albedo, refractive index, among others, provided by the AERONET retrieval algorithm); here, we retrieve the aerosol
components explicitly. The approach also bridges directly to the quantities
used in global chemical transport models. We first tested the approach with
synthetic data to estimate the uncertainty, and then applied it to real
ground-based AERONET and spaceborne POLDER/PARASOL observations; thus, the
study presents a first attempt to derive aerosol components from satellite observations specifically tied to global chemical transport model quantities. Our results
indicate aerosol optical characteristics that are highly consistent with
standard products (e.g., R of ∼0.9 for aerosol optical
thickness) and demonstrate an ability to separate intrinsic optical
properties of fine- and coarse-sized aerosols. We applied our method to
POLDER/PARASOL radiances on the global scale and obtained spatial and
temporal patterns of the aerosol components that agree well with existing
knowledge on aerosol sources and transport features. Finally, we discuss
limitations and perspectives of this new technique.
•The mechanical capacity of TRM reinforced wall was increased an average of 204%.•The energy dissipation capacity for small displacements (<1 cm) was higher in the unreinforced masonry.•The higher ...ductility related to the TRM was also observed in the cumulative energy loss.•TRM reinforcement could guarantee the structural stability, preserving at least 40% of the initial stiffness even after suffering a 30 mm drift.•TRM layers also modified the cracking pattern.
The current experimental study is focused on the mechanical performance of masonry walls under in-plane cyclic shear forces. All specimens were fabricated with a central window, in which the geometry considered the recommendations of the Spanish structural seismic design code. Windows represent a weak area in the masonry structure, in which there are stress concentrations responsible for crack initiation. In order to improve the mechanical strength and ductility, a reinforcement with a Textile Reinforced Mortar (TRM) was used on both sides of the wall. The performance of the unreinforced and reinforced masonry has been discussed in terms of strength and ductility gain, stiffness degradation and energy dissipation capacity. The experimental tests comprised an initial vertical preload, and shear cycles with increasing amplitude. All tests were monitored by means of traditional displacement transducers, and digital image correlation. The analysis of the images showed the time evolution of the overall crack distribution. The TRM effect could be observed as an increase of the mechanical strength (maximum shear from 120 kN to more than 300 kN), higher displacements (drift from 9 to 35 mm), and more energy dissipation (the cumulative energy loss from 2.7 to 12.7 kN·m). In addition, the TRM reinforcements were capable of controlling the crack initiation and growth. The widespread crack along mortar joints observed in the unreinforced masonry became localized cracks (from the window’s corners mainly), in which crack growth direction was not determined by masonry joints.
Architectural heritage is usually built with masonry structures, which present problems under lateral in-plane loading conditions, such as wind pressure or earthquakes. In order to improve the shear ...behavior of masonry, the use of a fabric-reinforced cementitious matrix (FRCM) has become an interesting solution because of its synergy of mechanical properties and compatibility with masonry substrates. For a proper structural evaluation, the mechanical behavior of reinforced masonry and the FRCM itself needs to be characterized. Hence, a numerical model to evaluate the FRCM reinforcement requires some mechanical parameters that may be difficult to obtain. In this sense, the shear behavior of masonry can be evaluated by means of diagonal tension tests on small specimens (71 × 71 cm). In this work, a digital image correlation (DIC) monitoring system was used to control displacements and cracking patterns of masonry specimens under shear stress (induced by diagonal tension with FRCM layers) applied to one or two sides. In addition, the mechanical behavior of FRCM coupons under uniaxial tensile tests was also registered with DIC. The displacement measurements obtained by DIC were validated with the measurements registered with LVDT. Unlike LVDT-based techniques, DIC monitoring allowed us to measure deformations in masonry during the full test, detecting crack initiation even before it was visible to the eye.
Long-range-transported Canadian smoke layers in the stratosphere over
northern France were detected by three lidar systems in August 2017. The
peaked optical depth of the stratospheric smoke layer
...exceeds 0.20 at 532 nm, which is
comparable with the simultaneous tropospheric aerosol optical depth. The
measurements of satellite sensors revealed that the observed stratospheric
smoke plumes were transported from Canadian wildfires after being lofted by
strong pyro-cumulonimbus. Case studies at two observation sites, Lille (lat
50.612, long 3.142, 60 m a.s.l.) and Palaiseau (lat 48.712, long 2.215,
156 m a.s.l.), are presented in detail. Smoke particle depolarization
ratios are measured at three wavelengths: over 0.20 at 355 nm, 0.18–0.19 at
532 nm, and 0.04–0.05 at 1064 nm. The high depolarization ratios and their
spectral dependence are possibly caused by the irregular-shaped aged smoke
particles and/or the mixing with dust particles. Similar results are found by
several European lidar stations and an explanation that can fully resolve
this question has not yet been found. Aerosol inversion based on lidar
2α+3β data derived a smoke effective radius of about
0.33 µm for both cases. The retrieved single-scattering albedo is
in the range of 0.8 to 0.9, indicating that the smoke plumes are absorbing.
The absorption can cause perturbations to the temperature vertical profile,
as observed by ground-based radiosonde, and it is also related to the ascent
of the smoke plumes when exposed in sunlight. A direct radiative
forcing (DRF) calculation is performed using the obtained optical and
microphysical properties. The calculation revealed that the smoke plumes in
the stratosphere can significantly reduce the radiation arriving at the
surface, and the heating rate of the plumes is about 3.5 K day−1. The
study provides a valuable characterization for aged smoke in the
stratosphere, but efforts are still needed in reducing and quantifying the
errors in the retrieved microphysical properties as well as radiative forcing
estimates.
Lugdunin is the first reported nonribosomally synthesized antibiotic from human microbiomes. Its production by the commensal
eliminates the pathogen
from human nasal microbiomes. The ...cycloheptapeptide lugdunin is the founding member of the new class of fibupeptide antibiotics, which have a novel mode of action and represent promising new antimicrobial agents. How
releases and achieves producer self-resistance to lugdunin has remained unknown. We report that two ABC transporters encoded upstream of the lugdunin-biosynthetic operon have distinct yet overlapping roles in lugdunin secretion and self-resistance. While deletion of the
transporter genes abrogated most of the lugdunin secretion, the
transporter genes had a dominant role in resistance. Yet all four genes were required for full-level lugdunin resistance. The small accessory putative membrane protein LugI further contributed to lugdunin release and resistance levels conferred by the ABC transporters. Whereas LugIEFGH also conferred resistance to lugdunin congeners with inverse structures or with amino acid exchange at position 6, they neither affected the susceptibility to a lugdunin variant with an exchange at position 2 nor to other cyclic peptide antimicrobials such as daptomycin or gramicidin S. The obvious selectivity of the resistance mechanism raises hopes that it will not confer cross-resistance to other antimicrobials or to optimized lugdunin derivatives to be used for the prevention and treatment of
infections.
Thrombocytopenia is frequently encountered in infants with necrotizing enterocolitis (NEC). To develop a preclinical model of NEC-related thrombocytopenia, we measured serial platelet counts in ...10-d-old (P10) mouse pups with trinitrobenzene sulfonic acid (TNBS)-induced NEC-like injury. We also measured platelet volume indices, immature platelet fraction (IPF), and megakaryocyte number/ploidy in these animals.
Platelet counts, platelet volume indices, and IPF were measured in control (N = 65) and TNBS-treated pups (N = 104) using an automated hematology analyzer. Bone marrow megakaryocyte number, ploidy and CD41 expression were measured by flow cytometry. These findings were confirmed in a small cohort of P3 mice with NEC-like injury.
Murine pups with TNBS-mediated NEC-like injury developed thrombocytopenia at 15-24 h after exposure to TNBS. Intestinal injury was associated with increased platelet volume indices (mean platelet volume, platelet-to-large cell ratio, and platelet distribution width), and IPF, indicating increased thrombopoiesis. These mice also showed increased megakaryocyte number, ploidy, and CD41 expression, indicating increased megakaryocyte differentiation.
Similar to human NEC, murine NEC-like injury was also associated with decreased platelet counts. There was evidence of increased megakaryocyte differentiation and thrombopoiesis, which favors peripheral consumption of platelets as the likely mechanism of thrombocytopenia in these animals, over decreased platelet production.
Display omitted
•Two full-scale timbrel vaults have been constructed and tested.•The paper discusses the efficacy of TRM materials for the repairing of damaged timbrel vaults subjected to soil ...settlements.•TRM radial configurations restored the vaults continuity.•TRM radial configurations increased the vaults displacement capacity.
This paper presents the experimental results obtained from tests on two masonry vaults reinforced by Textile Reinforced Mortar (TRM) materials subjected to monotonic and cyclic vertical settlements in one of their supports. Two full-scale square masonry timbrel vaults were built in one of ICITECH’s laboratories at the Universitat Politecnica de Valencia (Valencia, Spain) using the traditional Catalan layered-construction technique, with various layers of clay tiles arranged in two perpendicular masonry textures joined by lime and cement mortar joints. Due to their peculiar geometric and mechanical features, i.e. their high slenderness ratio, low tensile strength and high material heterogeneity, these structures are especially prone to damage from high-risk events such as soil settlement or seismic excitation. To evaluate their response to vertical support displacements, both vaults were pre-damaged by either vertical monotonic or cyclic settlements. They were then strengthened by a radial TRM strengthening configuration and re-tested until failure. A complex network of traditional and optical sensors was used to monitor displacements, deformation and the development of the cracking mechanism under both settlement conditions. The results obtained show that TRM materials can be used to effectively repair severely damaged masonry timbrel vaults, helping to partially restore the initial elastic stiffness, as well as doubling the vaults’ elastic phase and ultimate displacements. In addition, TRM materials did not alter the stiffness degradation trend, although they had a strong effect on peak reaction degradation and failure modes. This investigation represents a valuable and unique source of information about the efficacy of TRM materials to repair full-scale pre-damaged masonry timbrel vaults.
PDF
