FeRh attracts intensive interest in antiferromagnetic (AFM) spintronics due to its first-order phase transition between the AFM and ferromagnetic (FM) phase, which is unique for exploring spin ...dynamics in coexisting phases. Here, we report lateral spin pumping by which angular momentum is transferred from FM domains into the AFM matrix during the phase transition of ultrathin FeRh films. In addition, FeRh is verified to be both an efficient spin generator and an efficient spin sink, by electrically probing vertical spin pumping from FM-FeRh into Pt and from Py into FeRh, respectively. A dramatic enhancement of damping related to AFM-FeRh is observed during the phase transition, which we prove to be dominated by lateral spin pumping across the FM/AFM interface. The discovery of lateral spin pumping provides insight into the spin dynamics of magnetic thin films with mixed-phases, and the significantly modulated damping advances its potential applications, such as ultrafast spintronics.
One of the most basic tasks of every cell is the synthesis of ribosomes, yet the process is so complex that we are only beginning to comprehend it. In human cells, the final product contains four ...RNAs and 79 proteins forming a large ribonucleoprotein, the ribosome. About twice as many factors are involved in assembly of these protein synthesizing machines. Additionally, some 200 small nucleolar ribonucleoproteins (snoRNPs) function in the modification of pre-ribosomal RNA (pre-rRNA) at a similar number of ribonucleotides. Modification is essential for proper function and biogenesis of ribosomes (Decatur and Fournier 2002; Sloan et al. 2016). While abrogation of individual modifications has little to no measurable effects, removal of a combination of modifications or of all causes severe to lethal effects. Modifications mostly cluster around the functional centers of the ribosome and some modifications are important for ribosome assembly. The subject of this perspective is to raise awareness to how modification at so many sites can be achieved while the pre-rRNA is being processed, folded and re-folded, and assembled with ribosomal proteins to yield the pre-ribosomal subunits in the nucleolus (Baßler and Hurt 2019). This is not a comprehensive review but a simplification of complex issues providing access to the general reader.
En este trabajo se discute la metodología de la filosofía matematizada y se argumenta a favor de un pluralismo metodológico de métodos formales y matemáticos. Se expone brevemente como es que otros ...tipos de hacer filosofía no cumplen con lo que la filosofía matematizada sí cumple, i.e. un rigor por claridad, objetividad y éxito interdisciplinario. Se mencionan varios ejemplos de filosofía matematizada, y se expone un ejemplo fe la teoría de la utilidad epistémica. Se argumenta a favor de una aproximación interdisciplinaria y de una ciencia unificada en cuanto a la filosofía.
En este trabajo se discute la metodología de la filosofía matematizada y se argumenta a favor de un pluralismo metodológico de métodos formales y matemáticos. Se expone brevemente como es que otros ...tipos de hacer filosofía no cumplen con lo que la filosofía matematizada sí cumple, i.e. un rigor por claridad, objetividad y éxito interdisciplinario. Se mencionan varios ejemplos de filosofía matematizada, y se expone un ejemplo fe la teoría de la utilidad epistémica. Se argumenta a favor de una proximación interdisciplinaria y de una ciencia unificada en cuanto a la filosofía.
Driven by transmembrane electrochemical ion gradients, F-type ATP synthases are the primary source of the universal energy currency, adenosine triphosphate (ATP), throughout all domains of life. The ...ATP synthase found in the thylakoid membranes of photosynthetic organisms has some unique features not present in other bacterial or mitochondrial systems. Among these is a larger-than-average transmembrane rotor ring and a redox-regulated switch capable of inhibiting ATP hydrolysis activity in the dark by uniquely adapted rotor subunit modifications. Here, we review recent insights into the structure and mechanism of ATP synthases specifically involved in photosynthesis and explore the cellular physiological consequences of these adaptations at short and long time scales.
The chloroplast adenosine triphosphate (ATP) synthase uses the electrochemical proton gradient generated by photosynthesis to produce ATP, the energy currency of all cells. Protons conducted through ...the membrane-embedded F
motor drive ATP synthesis in the F
head by rotary catalysis. We determined the high-resolution structure of the complete cF
F
complex by cryo-electron microscopy, resolving side chains of all 26 protein subunits, the five nucleotides in the F
head, and the proton pathway to and from the rotor ring. The flexible peripheral stalk redistributes differences in torsional energy across three unequal steps in the rotation cycle. Plant ATP synthase is autoinhibited by a β-hairpin redox switch in subunit γ that blocks rotation in the dark.
Hydrogen bond symmetrisations in H-bonded systems triggered by pressure-induced nuclear quantum effects (NQEs) is a long-known concept but experimental evidence in high-pressure ices has remained ...elusive with conventional methods. Theoretical works predicted quantum-mechanical tunneling of protons within water ices to occur at pressures above 30 GPa, and the H-bond symmetrisation transition to occur above 60 GPa. Here we used
H-NMR on high-pressure ice up to 97 GPa, and demonstrate that NQEs govern the behavior of the hydrogen bonded protons in ice VII already at significantly lower pressures than previously expected. A pronounced tunneling mode was found to be present up to the highest pressures of 97 GPa, well into the stability field of ice X, where NQEs are not anticipated in a fully symmetrised H-bond network. We found two distinct transitions in the NMR shift data at about 20 GPa and 75 GPa attributed to the step-wise symmetrisation of the H-bond.
Magnetic skyrmions are topologically protected whirls that decay through singular magnetic configurations known as Bloch points. We used Lorentz transmission electron microscopy to infer the ...energetics associated with the topological decay of magnetic skyrmions far from equilibrium in the chiral magnet Fe
Co
Si. We observed that the lifetime τ of the skyrmions depends exponentially on temperature, Formula: see text. The prefactor τ
of this Arrhenius law changes by more than 30 orders of magnitude for small changes of the magnetic field, reflecting a substantial reduction of the lifetime of skyrmions by entropic effects and, thus, an extreme case of enthalpy-entropy compensation. Such compensation effects, being well known across many different scientific disciplines, affect topological transitions and, thus, topological protection on an unprecedented level.
El realismo estructural óntico afirma que no existen objetos individuales, sólo estructuras. Habitualmente, se cree que esta postura está basada en la física contemporánea. Sus simpatizantes ...concluyen que, al nivel ontológico más fun- damental, no hay objetos. En este trabajo, bosquejaré este punto de vista; antes discutiré las posiciones desarrolladas a favor de la primacía de la física y sobre cómo el realismo estructural óntico no tiene sentido en las ciencias especiales; este principio no ayuda en la discusión del realismo estructural. Además, abor- daré cómo el realismo estructural óntico puede tener sentido en otras discipli- nas distintas a la física. Para mostrar esto, plantearé un caso donde el realismo estructural óntico es plausible en la lingüística.
Box H/ACA ribonucleoproteins (RNPs), each consisting of one unique guide RNA and 4 common core proteins, constitute a family of complex enzymes that catalyze, in an RNA-guided manner, the ...isomerization of uridines to pseudouridines (Ψs) in RNAs, a reaction known as pseudouridylation. Over the years, box H/ACA RNPs have been extensively studied revealing many important aspects of these RNA modifying machines. In this review, we focus on the composition, structure, and biogenesis of H/ACA RNPs. We explain the mechanism of how this enzyme family recognizes and specifies its target uridine in a substrate RNA. We discuss the substrates of box H/ACA RNPs, focusing on rRNA (rRNA) and spliceosomal small nuclear RNA (snRNA). We describe the modification product Ψ and its contribution to RNA function. Finally, we consider possible mechanisms of the bone marrow failure syndrome dyskeratosis congenita and of prostate and other cancers linked to mutations in H/ACA RNPs.
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