3,480 research outputs found

    Lanthanide-Based Complexes Containing a Chiral trans-1,2-Diaminocyclohexane (DACH) Backbone: Spectroscopic Properties and Potential Applications

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    In this minireview, we give an overview on the use of the chiral molecule trans-1,2-diaminocyclohexane (DACH) in several fields of application. This chiral backbone is present in a variety of metal complexes which are employed in (enantioselective) catalysis, chiral discrimination, molecular recognition and supramolecular chemistry. Metal extraction and biochemical and pharmaceutical applications also use the DACH molecule. This contribution is particularly focused on the interesting chemical-physical properties discussed so far in the literature concerning lanthanide-based complexes containing chiral ligands characterized by the presence of DACH in the structure. In particular, the interconnection between luminescence (total and circularly polarized), structure and thermodynamics of Eu(III), Tb(III) and Sm(III) complexes will be discussed also in light of their use as optical or chiroptical probes for the sensing of important analytes dissolved in aprotic and protic polar solvents. Several complexes show potential interest in the solid state as phosphors for light emitting devices or for the detection of volatile organic compounds

    Leptogenesis implications in models with Abelian family symmetry and one extra real Higgs singlet

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    We show that the neutrino models, as suggested by Low, which have an additional Abelian family symmetry and a real Higgs singlet to the default see-saw do not hinder the possibility of successful thermal leptogenesis. For these models (neglecting radiative effects), we have investigated the situation of strong washout in both the one-flavor approximation and when flavor effects are included. The result is that while such models predict that theta_{13}=0 and that one light neutrino to be massless, they do not modify or provide significant constraints on the typical leptogenesis scenario where the final asymmetry is dominated by the decays of the lightest right-handed neutrinos.Comment: 18 pages, RevTeX4, accepted by Phys. Rev. D. v2: minor corrections, note and 1 ref. added, same content as published versio

    A scoping review of burden of disease studies estimating disability-adjusted life years due to Taenia solium

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    Background Taenia solium is the most significant global foodborne parasite and the leading cause of preventable human epilepsy in low and middle-income countries in the form of neurocysticercosis. Objectives This scoping review aimed to examine the methodology of peer-reviewed studies that estimate the burden of T. solium using disability-adjusted life years. Eligibility criteria Studies must have calculated disability-adjusted life years relating to T. solium. Charting methods The review process was managed by a single reviewer using Rayyan. Published data relating to disease models, data sources, disability-adjusted life years, sensitivity, uncertainty, missing data, and key limitations were collected. Results 15 studies were included for review, with seven global and eight national or sub-national estimates. Studies primarily employed attributional disease models that relied on measuring the occurrence of epilepsy before applying an attributable fraction to estimate the occurrence of neurocysticercosis-associated epilepsy. This method relies heavily on the extrapolation of observational studies across populations and time periods; however, it is currently required due to the difficulties in diagnosing neurocysticercosis. Studies discussed that a lack of data was a key limitation and their results likely underestimate the true burden of T. solium. Methods to calculate disability-adjusted life years varied across studies with differences in approaches to time discounting, age weighting, years of life lost, and years of life lived with disability. Such differences limit the ability to compare estimates between studies. Conclusions This review illustrates the complexities associated with T. solium burden of disease studies and highlights the potential need for a burden of disease reporting framework. The burden of T. solium is likely underestimated due to the challenges in diagnosing neurocysticercosis and a lack of available data. Advancement in diagnostics, further observational studies, and new approaches to parameterising disease models are required if estimates are to improve

    Short-Term Efficacy of Upper-Extremity Exercise Training in Patients With Chronic Airway Obstruction: A Systematic Review.

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    Background, Objectives, and Measurements Patients with chronic airway obstruction (CAO) frequently experience dyspnea and fatigue during activities performed by accessory muscles of ventilation, which competitively participate in arm elevation. This systematic review of randomized controlled trials (RCTs) concerning patients with CAO addresses the effects of upper-extremity exercise training (UEET), added to lower-extremity training or comprehensive pulmonary rehabilitation, on the following patient-centered outcomes: exercise capacity, symptoms, ability to perform daily activities, and health-related quality of life. METHODS:/b> Studies were retrieved using comprehensive database and hand-search strategies. Two independent reviewers determined study eligibility based on inclusion criteria. A detailed description of treatments was mandatory. Reviewers rated study quality and extracted information on study methods, design, intervention, and results. RESULTS: /b> Forty publications were evaluated. Four RCTs met the inclusion criteria but had serious methodological limitations, which introduce possible biases that reduce their internal validity. The outcomes measured were heterogeneous, and the results were inconsistent regarding maximal exercise capacity, dyspnea, and health-related quality of life. No effect of UEET was demonstrated for measures of arm fatigue. Limitations and CONCLUSIONS:/b> The limited methodological quality of the studies retrieved prevented us from performing a meta-analysis, the results of which could be misleading. This systematic review shows that there is limited evidence examining UEET and that the evidence available is of poor quality. Therefore, a recommendation for the inclusion or exclusion of UEET in pulmonary rehabilitation programs for individuals with CAO is not possible. Further research is needed to definitively ascertain the effects of this training modality on patient-centered outcomes

    Biological variations in a long-term ex situ cultivation: a Mediterranean demosponge as model system

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    The demosponge Tethya citrina Sarà & Melone was subjected to long-term aquarium farming, considering that several species belonging to this genus are a rich source of useful bioactive metabolites. The rearing method in the present research was mainly based on applying parameters taken from the current literature. The sponge's biological activity was assessed in terms of survival and growth over time; status of filtering apparatus; protein banding profiles. Farmed sponges showed a high survival rate and marked reduction in size. In addition, they were frequently affected by massive production of asexual buds. Histological and ultrastructural observations showed a gradual disorganization of the sponge choanocyte chambers, with a drastic reduction in choanocytes and a progressive increase in spherulous cells. Comparative electrophoretic analysis of the protein profiles of wild and reared specimens showed differences in protein composition and abundance between the tested groups. Such data are consistent with the increase in spherulous cells whose content was markedly electron-dense, a feature stressing the proteinaceous nature of these inclusions. Experimental tank-rearing of Tethya provided promising responses in terms of high survival rate of the species and easy reproduction, though the rearing protocol used led to profound morpho-functional changes in the sponge. This confirms the inadequate state of knowledge on farming techniques for this taxon, while also highlighting potential applications in biotechnology of ex situ breeding techniques, in order to modify the sponges' biological responses

    Multi-step exploitation of raw arundo donax L. For the selective synthesis of second-generation sugars by chemical and biological route

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    Lignocellulosic biomass represents one of the most important feedstocks for future biorefineries, being a precursor of valuable bio-products, obtainable through both chemical and biological conversion routes. Lignocellulosic biomass has a complex matrix, which requires the careful development of multi-step approaches for its complete exploitation to value-added compounds. Based on this perspective, the present work focuses on the valorization of hemicellulose and cellulose fractionsof giant reed (Arundo donax L.) to give second-generation sugars, minimizing the formation of reaction by-products. The conversion of hemicellulose to xylose was undertaken in the presence of the heterogeneous acid catalyst Amberlyst-70 under microwave irradiation. The effect of the main reaction parameters, such as temperature, reaction time, catalyst, and biomass loadings on sugars yield was studied, developing a high gravity approach. Under the optimised reaction conditions (17 wt% Arundo donax L. loading, 160 °C, Amberlyst-70/Arundo donax L. weight ratio 0.2 wt/wt), the xylose yield was 96.3 mol%. In the second step, the cellulose-rich solid residue was exploited through the chemical or enzymatic route, obtaining glucose yields of32.5 and56.2 mol%, respectively. This work proves the efficiency of this innovative combination of chemical and biological catalytic approaches, for the selective conversion of hemicellulose and cellulose fractions of Arundo donax L. to versatile platform products

    Severe acute respiratory syndrome coronavirus 2 may exploit human transcription factors involved in retinoic acid and interferon-mediated response: a hypothesis supported by an in silico analysis

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    The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19), resulting in acute respiratory disease, is a worldwide emergency. Because recently it has been found that SARS-CoV is dependent on host transcription factors (TF) to express the viral genes, efforts are required to understand the molecular interplay between virus and host response. By bioinformatic analysis, we investigated human TF that can bind the SARS-CoV-2 sequence and can be involved in viral transcription. In particular, we analysed the key role of TF involved in interferon (IFN) response. We found that several TF could be induced by the IFN antiviral response, specifically some induced by IFN-stimulated gene factor 3 (ISGF3) and by unphosphorylated ISGF3, which were found to promote the transcription of several viral open reading frame. Moreover, we found 22 TF binding sites present only in the sequence of virus infecting humans but not bat coronavirus RaTG13. The 22 TF are involved in IFN, retinoic acid signalling and regulation of transcription by RNA polymerase II, thus facilitating its own replication cycle. This mechanism, by competition, may steal the human TF involved in these processes, explaining SARS-CoV-2's disruption of IFN-I signalling in host cells and the mechanism of the SARS retinoic acid depletion syndrome leading to the cytokine storm. We identified three TF binding sites present exclusively in the Brazilian SARS-CoV-2 P.1 variant that may explain the higher severity of the respiratory syndrome. These data shed light on SARS-CoV-2 dependence from the host transcription machinery associated with IFN response and strengthen our knowledge of the virus's transcription and replicative activity, thus paving the way for new targets for drug design and therapeutic approaches

    Big Bang Nucleosynthesis with Gaussian Inhomogeneous Neutrino Degeneracy

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    We consider the effect of inhomogeneous neutrino degeneracy on Big Bang nucleosynthesis for the case where the distribution of neutrino chemical potentials is given by a Gaussian. The chemical potential fluctuations are taken to be isocurvature, so that only inhomogeneities in the electron chemical potential are relevant. Then the final element abundances are a function only of the baryon-photon ratio η\eta, the effective number of additional neutrinos ΔNν\Delta N_\nu, the mean electron neutrino degeneracy parameter ξˉ\bar \xi, and the rms fluctuation of the degeneracy parameter, σξ\sigma_\xi. We find that for fixed η\eta, ΔNν\Delta N_\nu, and ξˉ\bar \xi, the abundances of helium-4, deuterium, and lithium-7 are, in general, increasing functions of σξ\sigma_\xi. Hence, the effect of adding a Gaussian distribution for the electron neutrino degeneracy parameter is to decrease the allowed range for η\eta. We show that this result can be generalized to a wide variety of distributions for ξ\xi.Comment: 9 pages, 3 figures, added discussion of neutrino oscillations, altered presentation of figure
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