The use of hydrogen as an energy carrier within the scope of the decarbonisation of the world’s energy production and utilisation is seen by many as an integral part of this endeavour. However, the ...discussion around hydrogen technologies often lacks some perspective on the currently available technologies, their Technology Readiness Level (TRL), scope of application, and important performance parameters, such as energy density or conversion efficiency. This makes it difficult for the policy makers and investors to evaluate the technologies that are most promising. The present study aims to provide help in this respect by assessing the available technologies in which hydrogen is used as an energy carrier, including its main challenges, needs and opportunities in a scenario in which fossil fuels still dominate global energy sources but in which renewables are expected to assume a progressively vital role in the future. The production of green hydrogen using water electrolysis technologies is described in detail. Various methods of hydrogen storage are referred, including underground storage, physical storage, and material-based storage. Hydrogen transportation technologies are examined, taking into account different storage methods, volume requirements, and transportation distances. Lastly, an assessment of well-known technologies for harnessing energy from hydrogen is undertaken, including gas turbines, reciprocating internal combustion engines, and fuel cells. It seems that the many of the technologies assessed have already achieved a satisfactory degree of development, such as several solutions for high-pressure hydrogen storage, while others still require some maturation, such as the still limited life and/or excessive cost of the various fuel cell technologies, or the suitable operation of gas turbines and reciprocating internal combustion engines operating with hydrogen. Costs below 200 USD/kWproduced, lives above 50 kh, and conversion efficiencies approaching 80% are being aimed at green hydrogen production or electricity production from hydrogen fuel cells. Nonetheless, notable advances have been achieved in these technologies in recent years. For instance, electrolysis with solid oxide cells may now sometimes reach up to 85% efficiency although with a life still in the range of 20 kh. Conversely, proton exchange membrane fuel cells (PEMFCs) working as electrolysers are able to sometimes achieve a life in the range of 80 kh with efficiencies up to 68%. Regarding electricity production from hydrogen, the maximum efficiencies are slightly lower (72% and 55%, respectively). The combination of the energy losses due to hydrogen production, compression, storage and electricity production yields overall efficiencies that could be as low as 25%, although smart applications, such as those that can use available process or waste heat, could substantially improve the overall energy efficiency figures. Despite the challenges, the foreseeable future seems to hold significant potential for hydrogen as a clean energy carrier, as the demand for hydrogen continues to grow, particularly in transportation, building heating, and power generation, new business prospects emerge. However, this should be done with careful regard to the fact that many of these technologies still need to increase their technological readiness level before they become viable options. For this, an emphasis needs to be put on research, innovation, and collaboration among industry, academia, and policymakers to unlock the full potential of hydrogen as an energy vector in the sustainable economy.
Based on Thermodynamics and its well-established First and Second Laws, this work presents and explores their economics counterparts, introducing new concepts, variables, and equations. This ...includes, among others, the economic counterparts of temperature, reversibility and irreversibility, and entropy and entropy generation resulting from economic irreversibility. The meaning of the new concepts, variables, equations, and their messages are introduced and discussed considering simple yet relevant economic processes. The economic counterparts of the First and Second Law balance equations are set in addition to the base concepts and Laws. These are effective and valuable tools for the analysis of economic processes. Observations from selected economic activities are analyzed using the new concepts, variables, and equations.
In this work, we demonstrate for the first time the design and fabrication of microchip electrophoresis devices containing cross-shaped channels and spiral electrodes around the separation channel ...for microchip electrophoresis and capacitively coupled contactless conductivity detection. The whole device was prepared in a digital light processing–based 3D printer in poly(ethylene glycol) diacrylate resin. Outstanding X-Y resolution of the customized 3D printer ensured the fabrication of 40-μm cross section channels. The spiral channels were filled with melted gallium to form conductive electrodes around the separation channel. We demonstrate the applicability of the device on the separation of sodium, potassium, and lithium cations by microchip electrophoresis.
Graphical abstract
Gut Microbiome and Organ Fibrosis Costa, Carolina F F A; Sampaio-Maia, Benedita; Araujo, Ricardo ...
Nutrients,
01/2022, Letnik:
14, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Fibrosis is a pathological process associated with most chronic inflammatory diseases. It is defined by an excessive deposition of extracellular matrix proteins and can affect nearly every tissue and ...organ system in the body. Fibroproliferative diseases, such as intestinal fibrosis, liver cirrhosis, progressive kidney disease and cardiovascular disease, often lead to severe organ damage and are a leading cause of morbidity and mortality worldwide, for which there are currently no effective therapies available. In the past decade, a growing body of evidence has highlighted the gut microbiome as a major player in the regulation of the innate and adaptive immune system, with severe implications in the pathogenesis of multiple immune-mediated disorders. Gut microbiota dysbiosis has been associated with the development and progression of fibrotic processes in various organs and is predicted to be a potential therapeutic target for fibrosis management. In this review we summarize the state of the art concerning the crosstalk between intestinal microbiota and organ fibrosis, address the relevance of diet in different fibrotic diseases and discuss gut microbiome-targeted therapeutic approaches that are current being explored.
The monocyte chemoattractant protein 1 (MCP-1) belongs to the CC chemokine family and acts in the recruitment of C–C motif chemokine receptor 2 (CCR2)-positive immune cell types to inflammation ...sites. In testis, the MCP-1/CCR2 axis has been associated with the macrophage population’s functional regulation, which presents significant functions supporting germ cell development. In this context, herein, we aimed to investigate the role of the chemokine receptor CCR2 in mice testicular environment and its impact on male sperm production. Using adult transgenic mice strain that had the CCR2 gene replaced by a red fluorescent protein gene, we showed a stage-dependent expression of CCR2 in type B spermatogonia and early primary spermatocytes. Several parameters related to sperm production were reduced in the absence of CCR2 protein, such as Sertoli cell efficiency, meiotic index, and overall yield of spermatogenesis. Daily sperm production decreased by almost 40%, and several damages in the seminiferous tubules were observed. Significant reduction in the expression of important genes related to the Sertoli cell function (Cnx43, Vim, Ocln, Spna2) and meiosis initiation (Stra8, Pcna, Prdm9, Msh5) occurred in comparison to controls. Also, the number of macrophages significantly decreased in the absence of CCR2 protein, along with a disturbance in Leydig cell steroidogenic activity. In summary, our results show that the non-activation of the MCP-1/CCR2 axis disturbs the testicular homeostasis, interfering in macrophage population, meiosis initiation, blood–testis barrier function, and androgen synthesis, leading to the malfunction of seminiferous tubules, decreased testosterone levels, defective sperm production, and lower fertility index.
We report the discovery of a substantial stellar overdensity in the periphery of the Large Magellanic Cloud (LMC), found using public imaging from the first year of the Dark Energy Survey. The ...structure appears to emanate from the edge of the outer LMC disc at a radius ≈13
$_{.}^{\circ}$
5 due north of its centre, and stretches more than 10 kpc towards the east. It is roughly 1.5 kpc wide and has an integrated V-band luminosity of at least M
V
= −7.4. The stellar populations in the feature are indistinguishable from those in the outer LMC disc. We attempt to quantify the geometry of the outer disc using simple planar models, and find that only a disc with mild intrinsic ellipticity can simultaneously explain the observed stellar density on the sky and the azimuthal line-of-sight distance profile. We also see possible non-planar behaviour in the outer disc that may reflect a warp and/or flare, as well as deviations that resemble a ring-like structure between
${\sim }9^\circ \hbox{ and }12^\circ$
from the LMC centre. Based on all these observations, we conclude that our remote, stream-like feature is likely comprised of material that has been stripped from the outskirts of the LMC disc, although we cannot rule out that it represents a transient overdensity in the disc itself. We conduct a simple N-body simulation to show that either type of structure could plausibly arise due to the tidal force of the Milky Way; however, we also recognize that a recent close interaction between the LMC and the Small Magellanic Cloud may be the source of the stripping or perturbation. Finally, we observe evidence for extremely diffuse LMC populations extending to radii of ∼18.5 kpc in the disc plane (
${\approx } 20^\circ$
on the sky), corroborating previous spectroscopic detections at comparable distances.
Each complex network (or class of networks) presents specific topological features which characterize its connectivity and highly influence the dynamics of processes executed on the network. The ...analysis, discrimination, and synthesis of complex networks therefore rely on the use of measurements capable of expressing the most relevant topological features. This article presents a survey of such measurements. It includes general considerations about complex network characterization, a brief review of the principal models, and the presentation of the main existing measurements. Important related issues covered in this work comprise the representation of the evolution of complex networks in terms of trajectories in several measurement spaces, the analysis of the correlations between some of the most traditional measurements, perturbation analysis, as well as the use of multivariate statistics for feature selection and network classification. Depending on the network and the analysis task one has in mind, a specific set of features may be chosen. It is hoped that the present survey will help the proper application and interpretation of measurements.
Nearly all the star clusters with ages of ∼1–2 Gyr in both Magellanic Clouds exhibit an extended main-sequence turn-off (eMSTO) whose origin is under debate. The main scenarios suggest that the eMSTO ...could be either due to multiple generations of stars with different ages or to coeval stellar populations with different rotation rates. In this paper we use Hubble Space Telescope images to investigate the ∼80-Myr old cluster NGC 1755 in the LMC. We find that the MS is split with the blue and the red MS hosting about the 25 per cent and the 75 per cent of the total number of MS stars, respectively. Moreover, the MSTO of NGC 1755 is broadened in close analogy with what is observed in the ∼300-Myr-old NGC 1856 and in most intermediate-age Magellanic-Cloud clusters. We demonstrate that both the split MS and the eMSTO are not due to photometric errors, field-stars contamination, differential reddening, or non-interacting binaries. These findings make NGC 1755 the youngest cluster with an eMSTO. We compare the observed CMD with isochrones and conclude that observations are not consistent with stellar populations with difference in age, helium, or metallicity only. On the contrary, the split MS is well reproduced by two stellar populations with different rotation, although the fit between the observed eMSTO and models with different rotation is not fully satisfactory. We speculate whether all stars in NGC 1755 were born rapidly rotating, and a fraction has slowed down on a rapid time-scale, or the dichotomy in rotation rate was present already at star formation. We discuss the implication of these findings on the interpretation of eMSTO in young and intermediate-age clusters.
Objective
To determine the presence and identity of extracellular bacteriophage (phage) families, genera and species in the vagina of pregnant women.
Design
Descriptive, observational cohort study.
...Setting
São Paulo, Brazil.
Population
Pregnant women at 21–24 weeks’ gestation.
Methods
Vaginal samples from 107 women whose vaginal microbiome and pregnancy outcomes were previously determined were analysed for phages by metagenomic sequencing.
Main outcome measures
Identification of phage families, genera and species.
Results
Phages were detected in 96 (89.7%) of the samples. Six different phage families were identified: Siphoviridae in 69.2%, Myoviridae in 49.5%, Microviridae in 37.4%, Podoviridae in 20.6%, Herelleviridae in 10.3% and Inviridae in 1.9% of the women. Four different phage families were present in 14 women (13.1%), three families in 20 women (18.7%), two families in 31 women (29.1%) and one family in 31 women (29.1%). The most common phage species detected were Bacillus phages in 48 (43.6%), Escherichia phages in 45 (40.9%), Staphylococcus phages in 40 (36.4%), Gokushovirus in 33 (30.0%) and Lactobacillus phages in 29 (26.4%) women. In a preliminary exploratory analysis, there were no associations between a particular phage family, the number of phage families present in the vagina or any particular phage species and either gestational age at delivery or the bacterial community state type present in the vagina.
Conclusions
Multiple phages are present in the vagina of most mid‐trimester pregnant women.
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Bacteriophages are present in the vagina of most pregnant women.
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Bacteriophages are present in the vagina of most pregnant women.
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