1,600 research outputs found
Elastic properties of two-component grouts at short curing times: The role of bentonite
Two-component grout is nowadays the material most used for the backfilling phase in tunnelling with a shield machine. The operative simplicity of the technology and the fast hardening reaction between the two components are the main reasons that have contributed to the intensive spread of the use of this backfilling technique all around the world. Although bentonite is one of the basic ingredients for the grout production, its effect on the elastic properties of the grout has not been completely investigated so far. In this work, six different two-component grouts and their elastic properties have been studied by means of geophysical measurements. The six grouts were characterised by the same mix design and five different bentonites, while one grout had no bentonite. The variation of the dynamic parameters over time was analysed at short curing times (up to 24 h). In detail, the shear wave velocity, the dynamic moduli and Poisson's ratio were determined by means of the ultrasonic pulse velocity technique. The results show that the grouts with the bentonites have higher dynamic moduli than the grout without the bentonite. Moreover, a final analysis of the experimental data provided an analytical relationship to calculate the shear-wave velocity for each of the six grouts at any curing times
A new species of Turbanellidae (Gastrotricha, Macrodasyida) from Jamaica, with a key to species of Paraturbanella
The study falls within the framework of a wider research programme aimed at investigating the gastrotrich
diversity of the Tropical North-Western Atlantic (TNWA). A new macrodasyidan gastrotrich is described
from fine-medium sand collected at Duncans Bay, Jamaica. The description is based on observations carried
out on living specimens using differential interference contrast microscopy. Paraturbanella xaymacana
sp. n., the third gastrotrich taxon reported from Jamaica, is a mid-sized species, up to 564 \u3bcm long, with
a feeble peribuccal swelling. The most obvious autapomorphic traits pertain to the testes and the male
pore, both of which are located approximately at mid body, rather than at- or near the pharyngo-intestinal
junction as occur in the other species of the genus. Additional differences with congeners are discussed and
a key to the Paraturbanella species is provided, in the hope it will be useful to both gastrotrich experts and
marine ecologists who discover these microscopic metazoans during their research
Fgf9 inhibition of meiotic differentiation in spermatogonia is mediated by Erk-dependent activation of Nodal-Smad2/3 signaling and is antagonized by Kit Ligand
Both fibroblast growth factor 9 (Fgf9) and Kit Ligand (Kl) signal through tyrosine kinase receptors, yet they exert opposite effects on meiotic differentiation in postnatal spermatogonia, Fgf9 acting as a meiosis-inhibiting substance and Kl acting as a promoter of the differentiation process. To understand the molecular mechanisms that might underlie this difference, we tried to dissect the intracellular signaling elicited by these two growth factors. We found that both Fgf9 and Kl stimulate Erk1/2 activation in Kit+ (differentiating) spermatogonia, even though with different time courses, whereas Kl, but not Fgf9, elicits activation of the Pi3k-Akt pathway. Sustained Erk1/2 activity promoted by Fgf9 is required for induction of the autocrine Cripto-Nodal-Smad2/3 signaling loop in these cells. Nodal signaling, in turn, is essential to mediate Fgf9 suppression of the meiotic program, including inhibition of Stra8 and Scp3 expression and induction of the meiotic gatekeeper Nanos2. On the contrary, sustained activation of the Pi3k-Akt pathway is required for the induction of Stra8 expression elicited by Kl and retinoic acid. Moreover, we found that Kl treatment impairs Nodal mRNA expression and Fgf9-mediated Nanos2 induction, reinforcing the antagonistic effect of these two growth factors on the meiotic fate of male germ cells
Research Evidence and Implications on Migration Phenomena in Europe
This book provides a summary overview of the activities carried out
by the Diversity and Migration Lab, which was set up within the scope
of the FORTHEM international Alliance (Fostering Outreach within
European Regions, Transnational Higher Education and Mobility),
and concluded in September 2022
Atherosclerosis and Its Related Laboratory Biomarkers
Atherosclerosis constitutes a persistent inflammatory ailment, serving as the predominant underlying condition for coronary artery disease (CAD), peripheral artery disease (PAD), and cerebrovascular disease. The progressive buildup of plaques within the walls of medium- and large-caliber arteries characterizes the atherosclerotic process. This accumulation results in significant narrowing that impedes blood flow, leading to critical tissue oxygen deficiency. Spontaneous blockage of thrombotic vessels can precipitate stroke and myocardial infarction, which are complications representing the primary global causes of mortality. Present-day models for predicting cardiovascular risk incorporate conventional risk factors to gauge the likelihood of cardiovascular events over a ten-year span. In recent times, researchers have identified serum biomarkers associated with an elevated risk of atherosclerotic events. Many of these biomarkers, whether used individually or in combination, have been integrated into risk prediction models to assess whether their inclusion enhances predictive accuracy. In this review, we have conducted a comprehensive analysis of the most recently published literature concerning serum biomarkers associated with atherosclerosis. We have explored the potential utility of incorporating these markers in guiding clinical decisions
The Natriuretic Peptide System: A Single Entity, Pleiotropic Effects
In the modern scientific landscape, natriuretic peptides are a complex and interesting network of molecules playing pleiotropic effects on many organs and tissues, ensuring the maintenance of homeostasis mainly in the cardiovascular system and regulating the water-salt balance. The characterization of their receptors, the understanding of the molecular mechanisms through which they exert their action, and the discovery of new peptides in the last period have made it possible to increasingly feature the physiological and pathophysiological role of the members of this family, also allowing to hypothesize the possible settings for using these molecules for therapeutic purposes. This literature review traces the history of the discovery and characterization of the key players among the natriuretic peptides, the scientific trials performed to ascertain their physiological role, and the applications of this knowledge in the clinical field, leaving a glimpse of new and exciting possibilities for their use in the treatment of diseases
New Data on Reproductive System and Spermatozoa Confirm Macrodasys as a Model in Comparative Reproductive Analysis in Macrodasyida (Gastrotricha)
Gastrotricha Macrodasyida, aquatic worms, are primarily hermaphrodites with internal
cross-fertilization and indirect sperm transfer. Insightful information on this matter dates to 1978
and derives from an illuminating work focused on two Macrodasys species. The role as a “model”
of this taxon clashes, however, with the relative paucity of data concerning the ultrastructure of the
accessory organs involved in the sperm transfer. Therefore, we have undertaken a new study on
three additional species of Macrodasys focusing on the frontal and caudal organs and also on the
spermatozoa. Our observations confirmed the structural plan of the reproductive system reported
for the genus, but found some differences concerning the accessory reproductive organs. Most
importantly, we found spermatozoa inside the caudal organ of several single specimens, suggestive
of a more plausible hypothesis about sperm transfer modality in Macrodasys. In the spermatozoa, the
position of the mitochondrion outside rather than inside the nucleus has been confirmed as a major
difference between the spermatozoa of Macrodasys species and those of the other Macrodasyida. We
suggest that the peculiar structure of the mature spermatozoon of Macrodasys could derive from an incomplete process of spermatogenesis and hence it would be useful to infer phylogenetic alliances
Effect of different salting technologies on the chemical and microbiological characteristics of PDO Pecorino Siciliano cheese
The present work was carried out to evaluate
the effect of two salting technologies [dry salting (DS) and
the combined dry-brine salting (DBS)] on the chemicophysical
and microbiological characteristics of PDO Pecorino
Siciliano cheeses of different final weight (6 and
12 kg). Dry matter was significantly influenced by both
salting process and final size. Twelve kilogram cheeses
treated by DBS showed higher protein content with higher
soluble nitrogen per cent than 6 kg cheeses. Salt content
was in the range 3.1–4.0% on dry matter. The colour did
not show significant differences for any of the factors, but
12 kg cheeses subjected to DS showed higher yellow index
than the other cheeses. The resistance at 30% of strain was
influenced by cheese size, with 6 kg cheeses showing
higher resistances than 12 kg cheeses. All cheeses were
dominated by coccus LAB, but pseudomonads and Enterobacteriaceae
showed comparable levels of about 105 cfu/g.
Significant microbiological differences were evidenced
only for enterococci and yeasts concerning the final cheese
size. Thirteen species of LAB, belonging to five genera
(Enterococcus, Lactobacillus, Lactococcus, Pediococcus
and Streptococcus), were identified, but several spoilage/
pathogenic species were also identified, especially Pseudomonas
putida, Citrobacter freundii and Stenotrophomonas
maltophilia. LAB isolates were preliminary
evaluated for their physiological characteristics in view of developing autochthonous starters to improve the microbiological
quality of PDO Pecorino Siciliano cheese
Gastrotricha: A Marine Sister for a Freshwater Puzzle
Background: Within an evolutionary framework of Gastrotricha Marinellina flagellata and Redudasys fornerise bear special interest, as they are the only Macrodasyida that inhabit freshwater ecosystems. Notwithstanding, these rare animals are poorly known; found only once (Austria and Brazil), they are currently systematised as incertae sedis. Here we report on the rediscovery of Redudasys fornerise, provide an account on morphological novelties and present a hypothesis on its phylogenetic relationship based on molecular data. Methodology/Principal Findings: Specimens were surveyed using DIC microscopy and SEM, and used to obtain the 18 S rRNA gene sequence; molecular data was analyzed cladistically in conjunction with data from 42 additional species belonging to the near complete Macrodasyida taxonomic spectrum. Morphological analysis, while providing new information on taxonomically relevant traits (adhesive tubes, protonephridia and sensorial bristles), failed to detect elements of the male system, thus stressing the parthenogenetic nature of the Brazilian species. Phylogenetic analysis, carried out with ML, MP and Bayesian approaches, yielded topologies with strong nodal support and highly congruent with each other. Among the supported groups is the previously undocumented clade showing the alliance between Redudasys fornerise and Dactylopodola agadasys; other strongly sustained clades include the densely sampled families Thaumastodermatidae and Turbanellidae and most genera. Conclusions/Significance: A reconsideration of the morphological traits of Dactylopodola agadasys in light of the new information on Redudasys fornerise makes the alliance between these two taxa very likely. As a result, we create Anandrodasys gen. nov. to contain members of the previously described D. agadasys and erect Redudasyidae fam. nov. to reflect this novel relationship between Anandrodasys and Redudasys. From an ecological perspective, the derived position of Redudasys, which is deeply nested within the Macrodasyida clade, unequivocally demonstrates that invasion of freshwater by gastrotrichs has taken place at least twice, in contrast with the single event hypothesis recently put forward
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