5,991 research outputs found
Surfactants: physicochemical interactions with biological macromolecules
Macromolecules are essential cellular components in biological systems responsible for performing a large number of functions that are necessary for growth and perseverance of living organisms. Proteins, lipids and carbohydrates are three major classes of biological macromolecules. To predict the structure, function, and behaviour of any cluster of macromolecules, it is necessary to understand the interaction between them and other components through basic principles of chemistry and physics. An important number of macromolecules are present in mixtures with surfactants, where a combi- nation of hydrophobic and electrostatic interactions is responsible for the specific properties of any solution. It has been demonstrated that surfactants can help the formation of helices in some proteins thereby promot- ing protein structure formation. On the other hand, there is extensive research towards the use of surfac- tants to solubilize drugs and pharmaceuticals; there- fore, it is evident that the interaction between surfactants with macromolecules is important for many applications which includes environmental processes and the pharmaceutical industry. In this review, we describe the properties of different types of surfactants that are relevant for their physicochemical interactions with biological macromolecules, from macromoleculesâsurfactant complexes to hydrophobic and electrostatic interactions
Methane aromatization in a fluidized bed reactor: Parametric study
Methane aromatization is a promising technology for the transformation of natural gas into liquid products, but suffers from the problem of catalyst deactivation by coke. A two-zone fluidized bed reactor has been proposed as a tool to counteract the catalyst deactivation, by providing continuous catalyst regeneration in the same vessel where the main reaction is carried out. This work shows the effect of the main operating conditions (carburization temperature, reaction temperature, carburization time, nature of regenerating agent and feed flow and height of the hydrocarbon entry point). Optimal reduction time and temperature were 1 h and 350°C. Best conversion and selectivity were achieved at 700°C without catalyst deactivation in the TZFBR
Nirmatrelvir/ritonavir in COVID-19 patients with haematological malignancies: a report from the EPICOVIDEHA registry
COVID-19; Haematology; NirmatrelvirCOVID-19; HematologĂa; NirmatrelvirCOVID-19; Hematologia; NirmatrelvirBackground
Nirmatrelvir/ritonavir treatment decreases the hospitalisation rate in immunocompetent patients with COVID-19, but data on efficacy in patients with haematological malignancy are scarce. Here, we describe the outcome of nirmatrelvir/ritonavir treatment in a large cohort of the latter patients.
Methods
This is a retrospective cohort study from the multicentre EPICOVIDEHA registry (NCT04733729) on patients with haematological malignancy, who were diagnosed with COVID-19 between January and September 2022. Patients receiving nirmatrelvir/ritonavir were compared to those who did not. A logistic regression was run to determine factors associated with nirmatrelvir/ritonavir administration in our sample. Mortality between treatment groups was assessed with KaplanâMeier survival plots after matching all the patients with a propensity score. Additionally, a Cox regression was modelled to detect factors associated with mortality in patients receiving nirmatrelvir/ritonavir.
Findings
A total of 1859 patients were analysed, 117 (6%) were treated with nirmatrelvir/ritonavir, 1742 (94%) were treated otherwise. Of 117 patients receiving nirmatrelvir/ritonavir, 80% had received â„1 anti-SARS-CoV-2 vaccine dose before COVID-19 onset, 13% of which received a 2nd vaccine booster. 5% were admitted to ICU. Nirmatrelvir/ritonavir treatment was associated with the presence of extrapulmonary symptoms at COVID-19 onset, for example anosmia, fever, rhinitis, or sinusitis (aOR 2.509, 95%CI 1.448â4.347) and 2nd vaccine booster (aOR 3.624, 95%CI 1.619â8.109). Chronic pulmonary disease (aOR 0.261, 95%CI 0.093â0.732) and obesity (aOR 0.105, 95%CI 0.014â0.776) were not associated with nirmatrelvir/ritonavir use. After propensity score matching, day-30 mortality rate in patients treated with nirmatrelvir/ritonavir was 2%, significantly lower than in patients with SARS-CoV-2 directed treatment other than nirmatrelvir/ritonavir (11%, p = 0.036). No factor was observed explaining the mortality difference in patients after nirmatrelvir/ritonavir administration.
Interpretation
Haematological malignancy patients were more likely to receive nirmatrelvir/ritonavir when reporting extrapulmonary symptoms or 2nd vaccine booster at COVID-19 onset, as opposed to chronic pulmonary disease and obesity. The mortality rate in patients treated with nirmatrelvir/ritonavir was lower than in patients with targeted drugs other than nirmatrelvir/ritonavir.EPICOVIDEHA has received funds from Optics COMMIT (COVID-19 Unmet Medical Needs and Associated Research Extension) COVID-19 RFP program by GILEAD Science, United States (Project 2020-8223)
The Dark Magnetism of the Universe
Despite the success of Maxwell's electromagnetism in the description of the
electromagnetic interactions on small scales, we know very little about the
behaviour of electromagnetic fields on cosmological distances. Thus, it has
been suggested recently that the problems of dark energy and the origin of
cosmic magnetic fields could be pointing to a modification of Maxwell's theory
on large scales. Here, we review such a proposal in which the scalar state
which is usually eliminated be means of the Lorenz condition is allowed to
propagate. On super-Hubble scales, the new mode is essentially given by the
temporal component of the electromagnetic potential and contributes as an
effective cosmological constant to the energy-momentum tensor. The new state
can be generated from quantum fluctuations during inflation and it is shown
that the predicted value for the cosmological constant agrees with observations
provided inflation took place at the electroweak scale. We also consider more
general theories including non-minimal couplings to the space-time curvature in
the presence of the temporal electromagnetic background. We show that both in
the minimal and non-minimal cases, the modified Maxwell's equations include new
effective current terms which can generate magnetic fields from sub-galactic
scales up to the present Hubble horizon. The corresponding amplitudes could be
enough to seed a galactic dynamo or even to account for observations just by
collapse and differential rotation in the protogalactic cloud.Comment: Invited brief review to appear in Modern Physics Letters
CFD Analysis of a Micro-Rotor In Ground Effect
In this work, computational fluid dynamics is used to compare experimental results for a two-bladed small rotor
Out of Ground Effect and In Ground Effect conditions. The paper focuses on the evalutation and prediction of
the performance of the rotor and investigates the outwash generated in ground effect. Time and phase averaged
outflow velocities with two different scaling methods are compared with experiments. The results are also scaled
to a full-size rotor, and compared with the PAXman model of crew operating in close rotor proximity. A particle
pickup model is also used showing the dust cloud generated by the rotor
Stellar evolution and modelling stars
In this chapter I give an overall description of the structure and evolution
of stars of different masses, and review the main ingredients included in
state-of-the-art calculations aiming at reproducing observational features. I
give particular emphasis to processes where large uncertainties still exist as
they have strong impact on stellar properties derived from large compilations
of tracks and isochrones, and are therefore of fundamental importance in many
fields of astrophysics.Comment: Lecture presented at the IVth Azores International Advanced School in
Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars
and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta,
Azores Islands, Portugal in July 201
Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach
We use the Markov Chain Monte Carlo method to investigate a global
constraints on the modified Chaplygin gas (MCG) model as the unification of
dark matter and dark energy from the latest observational data: the Union2
dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the
cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the
cosmic microwave background (CMB) data. In a flat universe, the constraint
results for MCG model are,
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Combined acute hyperglycemic and hyperinsulinemic clamp induced profibrotic and proinflammatory responses in the kidney
Increase in matrix protein content in the kidney is a cardinal feature of diabetic kidney disease. While renal matrix protein content is increased by chronic hyperglycemia, whether it is regulated by acute elevation of glucose and insulin has not been addressed. In this study, we aimed to evaluate whether short duration of combined hyperglycemia and hyperinsulinemia, mimicking the metabolic environment of prediabetes and early type 2 diabetes, induces kidney injury. Normal rats were subjected to either saline infusion (control, n = 4) or 7 h of combined hyperglycemic- hyperinsulinemic clamp (HG+HI clamp; n = 6). During the clamp, plasma glucose and plasma insulin were maintained at about 350 mg/dl and 16 ng/ml, respectively. HG+HI clamp increased the expression of renal cortical transforming growth factor-ÎČ (TGF-ÎČ) and renal matrix proteins, laminin and fibronectin. This was associated with the activation of SMAD3, Akt, mammalian target of rapamycin (mTOR) complexes, and ERK signaling pathways and their downstream target events in the initiation and elongation phases of mRNA translation, an important step in protein synthesis. Additionally, HG+HI clamp provoked renal inflammation as shown by the activation of Toll-like receptor 4 (TLR4) and infiltration of CD68-positive monocytes. Urinary F2t isoprostane excretion, an index of renal oxidant stress, was increased in the HG+HI clamp rats. We conclude that even a short duration of hyperglycemia and hyperinsulinemia contributes to activation of pathways that regulate matrix protein synthesis, inflammation, and oxidative stress in the kidney. This finding could have implications for the control of short-term rises in blood glucose in diabetic individuals at risk of developing kidney disease. © 2014 the American Physiological Society
Canopy arthropod declines along a gradient of olive farming intensification
Arthropod declines have been linked to agricultural intensification. However, information about the
impacts of intensification is still limited for many crops, as is our understanding of the responses
of different arthropod taxa and trophic groups, thus hindering the development of effective
mitigation measures. We investigated the impacts of olive farming intensification on canopydwelling
arthropods in the Mediterranean region. Intensification involves the increased use of
agrochemicals, mechanisation and irrigation, but also structural changes from traditional orchards
with low densities of large and old trees, to intensive and superintensive orchards with high to
very high densities of smaller and younger trees, respectively. Canopy arthropods were vacuumsampled
at 53 sites representing the three orchard intensification levels, in spring, summer and
autumn 2017. We evaluated how the arthropod community varied across intensification levels, and
in response to orchard structure, management and landscape context. We found no changes in the
diversity of arthropod taxa across intensification levels after correcting for sample coverage, but
arthropod abundance declined markedly along the intensification gradient. Decreased abundance
was associated with changes in orchard structure, lower herbaceous cover, and higher herbicide
and insecticide use. The abundance of a specialized olive pest was lower in landscapes with higher
woodland cover. The negative effects of intensification were stronger in spring and summer than
in autumn, and parasitoids and predators were particularly affected. Overall, results suggest that
retaining herbaceous cover, reducing agrochemical inputs and preserving natural woody elements
in the landscape, may contribute to mitigate impacts of olive farming intensification on canopy
arthropods, particularly on beneficial speciesinfo:eu-repo/semantics/publishedVersio
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