Resonant Photoionization of CO2 up to the Fourth Ionization Threshold Pranjal, Prateek; González-Vázquez, Jesús; Bello, Roger Y. ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
01/2024, Volume:
128, Issue:
1
Journal Article
Peer reviewed
Open access
We present a comprehensive theoretical study of valence-shell photoionization of the CO2 molecule by using the XCHEM methodology. This method makes use of a fully correlated molecular electronic ...continuum at a level comparable to that provided by state-of-the-art quantum chemistry packages in bound-state calculations. The calculated total and angularly resolved photoionization cross sections are presented and discussed, with particular emphasis on the series of autoionizing resonances that appear between the first and the fourth ionization thresholds. Ten series of Rydberg autoionizing states are identified, including some not previously reported in the literature, and their energy positions and widths are provided. This is relevant in the context of ongoing experimental and theoretical efforts aimed at observing in real-time (attosecond time scale) the autoionization dynamics in molecules.
This paper assesses the significance of quality-of-capital (QoC) news shocks and their transmission through the credit channel in explaining aggregate fluctuations. Our framework is an estimated ...medium-scale DSGE model augmented with a financial sector where two alternative sources of news shocks are considered. One is a (standard) total-factor-productivity (TFP) news shock; the other is a QoC news shock. The latter has a clear meaning that enables a close link to be built up between financial markets and the macroeconomy through the credit and expectation channels, which greatly improves model fit and largely displaces TFP news shocks as a source of the business cycle. The significance of pure (rather than realized) news underscores the role of expectations.
•QoC news closely links credit channels and the macroeconomy.•Model fit to macroeconomic data improves when considering QoC news shocks.•QoC news largely displaces TFP news in explaining aggregate fluctuations.•QoC news helps improve agents’ expectations.•The significance of pure news underscores the expectation channel.
RBPs (RNA binding proteins) play critical roles in the cell by regulating mRNA transport, splicing, editing, and stability. The RBP SRSF3 (serine/arginine-rich splicing factor 3) is essential for ...blastocyst formation and for proper liver development and function. However, its role in the heart has not been explored.
To investigate the role of SRSF3 in cardiac function.
Cardiac SRSF3 expression was high at mid gestation and decreased during late embryonic development. Mice lacking SRSF3 in the embryonic heart showed impaired cardiomyocyte proliferation and died in utero. In the adult heart, SRSF3 expression was reduced after myocardial infarction, suggesting a possible role in cardiac homeostasis. To determine the role of this RBP in the adult heart, we used an inducible, cardiomyocyte-specific SRSF3 knockout mouse model. After SRSF3 depletion in cardiomyocytes, mice developed severe systolic dysfunction that resulted in death within 8 days. RNA-Seq analysis revealed downregulation of mRNAs encoding sarcomeric and calcium handling proteins. Cardiomyocyte-specific SRSF3 knockout mice also showed evidence of alternative splicing of mTOR (mammalian target of rapamycin) mRNA, generating a shorter protein isoform lacking catalytic activity. This was associated with decreased phosphorylation of 4E-BP1 (eIF4E-binding protein 1), a protein that binds to eIF4E (eukaryotic translation initiation factor 4E) and prevents mRNA decapping. Consequently, we found increased decapping of mRNAs encoding proteins involved in cardiac contraction. Decapping was partially reversed by mTOR activation.
We show that cardiomyocyte-specific loss of SRSF3 expression results in decapping of critical mRNAs involved in cardiac contraction. The molecular mechanism underlying this effect likely involves the generation of a short mTOR isoform by alternative splicing, resulting in reduced 4E-BP1 phosphorylation. The identification of mRNA decapping as a mechanism of systolic heart failure may open the way to the development of urgently needed therapeutic tools.
Using mixed quantum-classical dynamics, the lowest part of the UV absorption spectrum and the first deactivation steps of keto-cytosine have been investigated. The spectrum shows several strong ...peaks, which mainly come from the S(1) and S(2) states, with minor contributions from the S(3). The semiclassical trajectories, launched from these three states, clearly indicate that at least four states are involved in the relaxation of keto-cytosine to the ground state. Non-adiabatic transfer between the ππ* and nπ* excited states and deactivation via three-state conical intersections is observed in the very early stage of the dynamics. In less than 100 fs, a large amount of population is deactivated to the ground state via several mechanisms; some population remains trapped in the S(2) state. The latter two events can be connected to the fs and ps transients observed experimentally.
It is unclear how the mitochondrial fusion protein Optic atrophy 1 (OPA1), which inhibits cristae remodeling, protects from mitochondrial dysfunction. Here we identify the mitochondrial F
F
-ATP ...synthase as the effector of OPA1 in mitochondrial protection. In OPA1 overexpressing cells, the loss of proton electrochemical gradient caused by respiratory chain complex III inhibition is blunted and this protection is abolished by the ATP synthase inhibitor oligomycin. Mechanistically, OPA1 and ATP synthase can interact, but recombinant OPA1 fails to promote oligomerization of purified ATP synthase reconstituted in liposomes, suggesting that OPA1 favors ATP synthase oligomerization and reversal activity by modulating cristae shape. When ATP synthase oligomers are genetically destabilized by silencing the key dimerization subunit e, OPA1 is no longer able to preserve mitochondrial function and cell viability upon complex III inhibition. Thus, OPA1 protects mitochondria from respiratory chain inhibition by stabilizing cristae shape and favoring ATP synthase oligomerization.
Although electro‐organic synthesis is currently receiving renewed interest because of its potential to enable sustainability in chemical processes to value‐added products, challenges in process ...development persist: For reductive transformations performed in protic media, an inherent issue is the limited choice of metallic cathode materials that can effectively suppress the parasitic hydrogen evolution reaction (HER) while maintaining a high activity toward the targeted electro‐organic reaction. Current development trends are aimed at avoiding the previously used HER‐suppressing elements (Cd, Hg, and Pb) because of their toxicity. Here, this work reports the rational design of highly porous foam‐type binary and ternary electrocatalysts with reduced Pb content. Optimized cathodes are tested in electro‐organic reductions using an oxime to nitrile transformation as a model reaction relevant for the synthesis of fine chemicals. Their electrocatalytic performance is compared with that of the model CuSn7Pb15 bronze alloy that has recently been endorsed as the best cathode replacement for bare Pb electrodes. All developed metal foam catalysts outperform both bare Pb and the CuSn7Pb15 benchmark in terms of chemical yield and energetic efficiency. Moreover, post‐electrolysis analysis of the crude electrolyte mixture and the cathode's surfaces through inductively coupled plasma mass spectrometry (ICP‐MS) and scanning electron microscopy (SEM), respectively, reveal the foam catalysts’ elevated resistance to cathodic corrosion.
This work develops leaded foam‐type electrodes through the dynamic hydrogen bubble template (DHBT) method and tests them in electro‐organic reductions using an oxime to nitrile transformation for synthesis of fine chemicals. All developed catalysts outperformed both Pb and CuSn7Pb15 in terms of chemical yields and energy efficiency. The latter material is deemed the best replacement for Pb in reductive organo‐electrosynthesis.
Exosomes are released by most cells to the extracellular environment and are involved in cell-to-cell communication. Exosomes contain specific repertoires of mRNAs, microRNAs (miRNAs) and other ...non-coding RNAs that can be functionally transferred to recipient cells. However, the mechanisms that control the specific loading of RNA species into exosomes remain unknown. Here we describe sequence motifs present in miRNAs that control their localization into exosomes. The protein heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) specifically binds exosomal miRNAs through the recognition of these motifs and controls their loading into exosomes. Moreover, hnRNPA2B1 in exosomes is sumoylated, and sumoylation controls the binding of hnRNPA2B1 to miRNAs. The loading of miRNAs into exosomes can be modulated by mutagenesis of the identified motifs or changes in hnRNPA2B1 expression levels. These findings identify hnRNPA2B1 as a key player in miRNA sorting into exosomes and provide potential tools for the packaging of selected regulatory RNAs into exosomes and their use in biomedical applications.
Electric power quality is becoming more critical with time because of the increasing use of electronic devices in all areas of society: in industry, in the household, etc. Many kinds of disturbances ...can be produced in the grid due to external or internal causes, such as, for example, switching operations. Among them, distortion and imbalance are long-term disturbances, which makes them very dangerous for electric equipment. In addition, the identification of the distortion and/or imbalance sources is quite difficult because they are instantaneously scattered by the grid. This paper presents a study of the algorithms published in the technical literature which identify distortion and imbalance sources in electrical installations and compares the results of applying them to a specific installation constituted by linear and non-linear, balanced and unbalanced loads, and a standard module to inject energy to the grid. Only two algorithms have been found in the review carried out and the results provided by both are presented and discussed. Neither of these algorithms is completely reliable, although one of them is more promising.
Fretting fatigue failure occurs in shrink-fitted assemblies due to the combination of high stresses and relative displacements near the contact edge. Due to these high stresses, fatigue crack ...initiates followed by crack propagation until final rupture. Additive manufacturing (AM) is a game changing technology, which enables new component capabilities that cannot be manufactured with conventional techniques. This research work analyses numerically the influence of an artificial internal stress relief toroidal groove inside a shrink-fitted shaft, which could be manufactured using AM technology. Due to the toroidal void, the stress/strain fields are redistributed improving the fretting fatigue crack initiation and propagation lifetimes. To do so, 2D finite element models are created in Abaqus software with and without the internal groove. To estimate the fretting fatigue initiation and propagation lifetime and crack propagation direction, critical plane methods are used. In terms of the crack propagation, eXtended Finite Element Method (XFEM) is used to simulate mixed mode crack advancing in a single mesh structure. Finally, the obtained results with and without void were compared concluding with significant improvements in terms of total fatigue lifetime.
•Shrink-fitted shaft fretting fatigue palliative.•Evaluation and comparison of crack propagation direction methods.•Analysis of crack propagation direction using XFEM.•Voids could delay crack initiation and propagation stages.
Vaccine therapies based on virus-like particles (VLPs) are currently in the spotlight due to their potential for generating high immunogenic responses while presenting fewer side effects than ...conventional vaccines. These self-assembled nanostructures resemble the native conformation of the virus but lack genetic material. They are becoming a promising platform for vaccine candidates against several diseases due to the ability of modifying their membrane with antigens from different viruses. The coproduction of extracellular vesicles (EVs) when producing VLPs is a key phenomenon currently still under study. In order to characterize this extracellular environment, a quantitative proteomics approach has been carried out. Three conditions were studied: non-transfected, transfected with an empty plasmid as control, and transfected with a plasmid coding for HIV-1 Gag polyprotein. A shift in EV biogenesis has been detected upon transfection, changing the production from large to small EVs. Another remarkable trait found was the presence of DNA being secreted within vesicles smaller than 200 nm. Studying the protein profile of these biological nanocarriers, it was observed that EVs were reflecting an overall energy homeostasis disruption via mitochondrial protein deregulation. Also, immunomodulatory proteins like ITGB1, ENO3, and PRDX5 were identified and quantified in VLP and EV fractions. These findings provide insight on the nature of the VLP extracellular environment defining the characteristics and protein profile of EVs, with potential to develop new downstream separation strategies or using them as adjuvants in viral therapies.
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