bluuebunny/crossref_metadata_2025 huggingface dataset:
El equívoco de la producción. Una lectura política desde la apropiación
Authors: Becerra Villegas Jesús
Published: May 2022

El presente estudio retoma del campo académico de la comunicación la categoría Apropiación para ofrecer una lectura política de las complejidades contemporáneas del capitalismo. Al caracterizar éste como Modo de Producción, Marx puso de relieve ciertas propiedades oposicionales más cercanas al pensamiento económico que al político. El documento propone que las relaciones fundamentales del capitalismo, conforme se despliegan en el tiempo, se revelan más afines a la apropiación que a la producción, y que la densidad política de ellas es suficiente para recuperar como conflictivas mas no contradictorias las relaciones entre el capital productivo y las instituciones del Estado o ramas económicas como los sistemas financiero y de comunicación. Por otra parte, el desplazamiento de la categoría producción da paso a la esfera del consumo con su dimensión cultural, componente importante para pensar la naturaleza de los conflictos y la reproducción sociales.
La ciudadanía cosmopolita y «el derecho de gentes» de John Rawls
Authors: Santiago Juárez Rodrigo
Published: May 2022

El concepto de ciudadanía cosmopolita ha estado presente en el pensamiento filosófico desde la Ilustración. En la filosofía política contemporánea este concepto ha merecido la atención de algunos autores, aunque no todas sus propuestas han tenido el mismo éxito. En este trabajo se analizan algunas de las ideas que sobre la ciudadanía cosmopolita expuso John Rawls en su trabajo “El derecho de gentes”, y algunas críticas que pueden hacerse a esa propuesta.
Análisis crítico de la Ley 20.609, que establece medidas contra la discriminación, a la luz del derecho internacional de los derechos humanos y las convenciones de la OEA sobre discriminación de 2013
Authors: Gauché Marchetti Ximena Andrea
Published: May 2022

El 24 de julio de 2012 fue publicada la Ley 20.609, que establece medidas contra la discriminación, luego de años de tramitación legislativa y del impulso mediático que tuvo por acción de organizaciones de la sociedad civil tras la trágica muerte de Daniel Zamudio y la condena por discriminación de la Corte Interamericana de Derechos Humanos a Chile en el caso Atala. Su publicación fue celebrada y considerada un avance importante en materia de derechos humanos y claramente puede ser vista así. Sin embargo, en cuanto aporte decisivo frente a situaciones de discriminación, existen claras insuficiencias que se han ido levantando por la doctrina nacional. Este trabajo tiene como objetivo exponer el contenido y algunos antecedentes de esta ley de forma crítica a la luz del derecho internacional de los derechos humanos y las convenciones de la OEA aprobadas en 2013, tomando posición a favor de una reforma al cuerpo legal citado. Para ese propósito el trabajo se estructura en tres apartados que dan cuenta de los desarrollos internacionales; los antecedentes y contenido de la Ley 20.609 y, a modo de conclusiones, algunos de los cambios que se estiman deberían introducirse a la legislación nacional.
Discurso jurídico en debate: reparto y posibles cambios de sentido en el concepto de «ciudadanía»
Authors: Lell Helga María
Published: May 2022

La propuesta de este artículo es traer a colación algunas reflexio-nes en torno a si es recomendable, en términos de aumento o de retracción de los procesos de democratización, la inclusión de los extranjeros que cum-plan ciertas condiciones, en los padrones de electores «nacionales», esto es, entre los considerados ciudadanos políticamente activos. En particular, se pretende repensar cómo la presencia de los extranjeros en un determinado territorio estatal (comúnmente vinculado con la idea del espacio propio de lo «nacional») acciona mecanismos sociales de inclusión y de exclusión que son acompañados y respaldados por el discurso jurídico.
La acción popular en el sistema procesal español
Authors: Jiménez Cardona Noemí
Published: May 2022

El presente artículo tiene por objeto de estudio la institución de la acción popular como parte integrante de la acusación formulada dentro del proceso penal español. En concreto, centra su análisis en los requisitos objetivos, subjetivos y formales a cumplir, así como los límites tanto lega-les como jurisprudenciales a los que está sujeta su actuación. Asimismo, se perfilan las líneas de futuro venideras, haciendo especial referencia al Anteproyecto de Ley de Enjuiciamiento Criminal. A modo de conclusión, se proyectan toda una serie de apreciaciones tendentes al esclarecimiento y mejora, abogando por la permanencia, de esta institución tan emblemática como polémica.
La uniformidad jurisprudencial, herramienta del derecho fundamental a la igualdad en la aplicación de la ley
Authors: Díaz García Iván
Published: May 2022

El presente artículo evidencia que la pretensión de uniformar lajurisprudencia que traslucen las diversas reformas procesales operadas enel ordenamiento jurídico chileno en los últimos 20 años constituyen unaherramienta que hace posible el efectivo disfrute del derecho a la igualdaden la aplicación de la ley.
Las normas que dan origen a la responsabilidad civil y a la responsabilidad infraccional en la Ley 19.496
Authors: Isler Soto Erika
Published: May 2022

Si bien la Ley 19.496 sobre Protección de los Derechos de losConsumidores establece que de sus normas puede surgir responsabilidadcivil y responsabilidad infraccional o administrativa, no menciona expresamente la relación que existe entre una y otra. De la misma manera, la técnica legislativa no otorga claridad respecto de las normas que son fuente de una y otra. Este documento revisa lo que ha señalado la doctrina al respecto,así como los pronunciamientos judiciales de los cuales pudiera derivarseuna respuesta. La tesis que se adhiere es la unitaria, esto es, que todas lasnormas de esta Ley pueden dar origen indistintamente a la acción civil einfraccional.
Pensando un horizonte democrático, pluralista e intercultural para el reconocimiento de los pueblos indígenas en América Latina, desde una relectura crítica a Laclau y Mouffe
Authors: Faundes Peñafiel Juan Jorge
Published: May 2022

Desarrollamos la propuesta de un horizonte democrático, plura-lista e intercultural que corresponde a una visión de la democracia sostenidaen articulaciones democráticas, propias de un orden social nunca del todoalcanzable y presupuesto necesario del reconocimiento de la identidad cultural de los pueblos indígenas latinoamericanos, como sujetos constituyentes de los procesos de reconstitución de sus estados. Como punto de partida, revisamos el pluralismo agonístico de Laclau y Mouffe, releyéndolo crítica e interculturalmente, sosteniendo que el reconocimiento de la identidad cultural de los pueblos indígenas en América Latina supone la existencia de una relación dual y paradójica, entre conflicto y diálogo, que redefine el consenso racional comunicativo, desplaza la matriz liberal «igualdad-libertad» por una matriz «intercultural» que articula la diversidad como un nuevo imaginario democrático y marco institucional.
The Influence of Perceived Ease of Use and Perceived Usefulness on E-Wallet Continuance Intention
Authors: Olivia Michelle , Marchyta Nony Kezia
Published: May 2022

The developments of information technology and the advent of new normal in Indonesia had transformed how transaction was conducted, increasing the importance of e-wallet. This study aimed to analyze the effect of perceived ease of use, perceived usefulness, and customer satisfaction on e-wallet continuance intention. This study focused on customers of e-wallets in Indonesia. This research was quantitative research with data collection used the purposive sampling technique. This sampling was conducted by distributing questionnaires to 97 e-wallet customers in Indonesia, with eight questionnaires being rejected due to unmet criteria. Partial Least Square Path Modeling (PLSPM) was used to test the hypotheses. The study found that perceived ease of use had a direct positive influence on continuance intention as well as an indirect positive influence on it through customer satisfaction as an intervening variable, perceived enjoyment did not directly influence continuance intention but had indirect positive influence on it through customer satisfaction as an intervening variable, and customer satisfaction positively influenced continuan­ce intention
Biaxially Compressive Strain in Ni/Ru Core/Shell Nanoplates Boosts Li–CO2 Batteries
Authors: Fan Li , Shen Haoming , Ji Dongxiao , Xing Yi , Tao Lu , Sun Qiang , Guo Shaojun
Published: May 2022

Regulating surface strain of nanomaterials is an effective strategy to manipulate the activity of catalysts, yet not well recognized in rechargeable Li–CO2 batteries. Herein, biaxially compressive strained nickel/ruthenium core/shell hexagonal nanoplates (Ni/Ru HNPs) with lattice compression of ≈5.1% and ≈3.2% in the Ru {10−10} and (0002) facets are developed as advanced catalysts for Li–CO2 batteries. It is demonstrated that tuning the electronic structure of Ru shell through biaxially compressive strain engineering can boost the kinetically sluggish CO2 reduction and evolution reactions, thus achieving a high‐performance Li–CO2 battery with low charge platform/overpotential (3.75 V/0.88 V) and ultralong cycling life (120 cycles at 200 mA g−1 with a fixed capacity of 1000 mAh g−1). Density functional theory calculations reveal that the biaxially compressive strain can downshift the d‐band center of surface Ru atoms and thus weaken the binding of CO2 molecules, which is energetically beneficial for the nucleation and decomposition of Li2CO3 crystals during the discharge and charge processes. This study confirms that strain engineering, though constructing a well‐defined core/shell structure, is a promising strategy to improve the inherent catalytic activity of Ru‐based materials in Li–CO2 batteries.
Efficient, Stable, and Ultra‐Broadband Near‐Infrared Garnet Phosphors for Miniaturized Optical Applications
Authors: Dumesso Misgana U. , Xiao Wenge , Zheng Guojun , Basore Endale T. , Tang Mingxue , Liu Xiaofeng , Qiu Jianrong
Published: May 2022

Broadband near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are recently regarded as the next‐generation smart light sources for miniaturized optical applications. However, their way to practical applications is largely obstructed by the lack of efficient NIR phosphors with photoluminescence (PL) spectrum covering the whole range of 700–1100 nm. Here, an ultra‐broadband NIR phosphor is designed by rationally constructing a Cr3+ → Yb3+ energy transfer system in a garnet crystal Lu2CaMg2Ge3O12 (LCMG). The disordering of the neighboring cations of LCMG is exploited for removing the inversion symmetry of octahedrally coordinated Cr3+ to promote its parity‐forbidden d–d transition probability; meanwhile, efficient Cr3+Yb3+ energy transfer is leveraged not only to enrich the short‐wave NIR PL in 950–1100 nm, but also to greatly improve the internal quantum efficiency (QE) (from 57.8% to 84.2%) as well as thermal stability. The resulting high external QE (35.6%) enables the demonstration of ultra‐broadband NIR pc‐LED with a record NIR output power of 93.2 mW (350 mA), which promises better performance of pc‐LEDs in non‐visible optical applications. This work provides a possible paradigm for developing ultra‐broadband NIR phosphors activated by transition metal ions.
Photo De‐Mixing in Dion‐Jacobson 2D Mixed Halide Perovskites
Authors: Wang Ya‐Ru , Senocrate Alessandro , Mladenović Marko , Dučinskas Algirdas , Kim Gee Yeong , Rothlisberger Ursula , Milić Jovana V. , Moia Davide , Grätzel Michael , Maier Joachim
Published: May 2022

2D halide perovskites feature a versatile structure, which not only enables the fine‐tuning of their optoelectronic properties but also makes them appealing as model systems to investigate the fundamental properties of hybrid perovskites. In this study, the authors analyze the changes in the optical absorption of 2D Dion‐Jacobson mixed halide perovskite thin films (encapsulated) based on (PDMA)Pb(I0.5Br0.5)4 (PDMA: 1,4‐phenylenedimethanammonium spacer) exposed to a constant illumination. It is demonstrated that these 2D mixed‐halide perovskites undergo photo‐induced phase segregation, where the pristine mixed‐phase de‐mixes into iodide‐rich and bromide‐rich phases (photo de‐mixing). The de‐mixed state is largely maintained in the dark at room temperature for several months, while at higher temperatures it shows complete reversibility to the mixed‐phase in terms of optical and structural properties (dark re‐mixing). The authors further investigate temperature‐dependent absorption measurements under light to extract the photo de‐mixed compositions and to map the photo‐miscibility‐gap. This work thereby reveals that reversible photo de‐mixing occurs in Dion‐Jacobson 2D hybrid perovskites and provides strategies to address the role of light in the thermodynamic properties of these materials.
Air‐Degradation Mechanisms in Mixed Lead‐Tin Halide Perovskites for Solar Cells
Authors: Lim Vincent J.‐Y. , Ulatowski Aleksander M. , Kamaraki Christina , Klug Matthew T. , Miranda Perez Laura , Johnston Michael B. , Herz Laura M.
Published: May 2022

Owing to the bandgap‐bowing effect, mixed lead‐tin halide perovskites provide ideal bandgaps for the bottom subcell of all‐perovskite tandem photovoltaic devices that offer fundamentally elevated power‐conversion efficiencies. However, these materials suffer from degradation in ambient air, which worsens their optoelectronic properties and hinders their usability for photovoltaic applications. Such degradation pathways are not yet fully understood, especially for the perovskites in the middle of the APbxSn1‐xI3 solid solution line, which offer the narrowest bandgaps across the range. This study unravels the degradation mechanisms of APbxSn1‐xI3 perovskites, reporting clear differences between mixed lead‐tin (x = 0.5) and tin‐only (x = 0) perovskites. The dynamic optoelectronic properties, electronic structure, crystal structure, and decomposition products of the perovskite thin films are examined in situ during air exposure. Both perovskite compositions suffer from the formation of defects over the timescale of hours, as indicated by a significant reduction in their charge‐carrier diffusion lengths. For tin‐only perovskite, degradation predominantly causes the formation of energetically shallow tin vacancies and hole doping. However, for mixed lead‐tin perovskite, deep trap states are formed that significantly accelerate charge‐carrier recombination, yet leave mobilities relatively unaffected. These findings highlight the need for passivation strategies tailored specifically to mixed lead‐tin iodide perovskites.
Recent Advances onα‐Azidoketones and Esters in the Synthesis ofN‐Heterocycles
Authors: Borkotoky Lodsna , Maurya Ram Awatar
Published: May 2022

Organic azides have been proven to possess versatile reactivity that is utilized to synthesize a large number of molecular scaffolds. Among the azides,α‐azidoketones and esters have been widely explored to synthesize numerous high valuedN‐heterocycles. The enhanced acidity of the methylene hydrogen atoms by adjacent carbonyl or ester groups of α‐azidoketones and esters largely attributes to their unique chemical behaviour. It has been mostly utilized in two ways: a) the azides have been directly treated with other reagents in a basic medium and b) they are converted intoα‐azidovinylketones and esters through Knoevenagel condensation with aldehydes and subsequently treated with various reagents to access nitrogen heterocycles. This review provides a general outlook and concise report onα‐azidoketones and esters towards the synthesis of variousN‐heterocycles such as pyrroles, indoles, pyrazoles, imidazoles, triazoles, pyridines, pyrimidine, pyrazine and many others.
Different approaches to the study of the gravitational radiation emitted by astrophysical sources
Authors: Ferrari Valeria
Published: May 2022

Stars and black holes are sources of gravitational radiation in many phases of their life, and the signals they emit exhibit features that are characteristic of the generating process. Emitted since the beginning of star formation, these signals also contribute to create a stochastic background of gravitational waves. We shall show how the spectral properties of this background can be estimated in terms of the energy spectrum of each single event and of the star formation rate history, which is now deducible from astronomical observations. We shall further discuss the process of scattering of masses by stars and black holes, showing that, unlike black holes, stars emit signals that carry a clear signature of the nature of the source.
Tails of the density of states of two‐dimensional Dirac fermions
Authors: Villain‐Guillot S. , Jug G. , Ziegler K.
Published: May 2022

The density of states of Dirac fermions with a random mass on a two‐dimensional lattice is considered. We give the explicit asymptotic form of the single‐electron density of states as a function of both energy and (average) Dirac mass, in the regime where all states are localized. We make use of a weak‐disorder expansion in the parameter g/m2, where g is the strength of disorder and m the average Dirac mass for the case in which the evaluation of the (supersymmetric) integrals corresponds to non‐uniform solutions of the saddle point equation. The resulting density of states has tails which deviate from the typical pure Gaussian form by an analytic prefactor.
Numerical Relativity in 3+1 Dimensions
Authors: Brügmann B.
Published: May 2022

Numerical relativity is finally approaching a state where the evolution of rather general (3+1)‐dimensional data sets can be computed in order to solve the Einstein equations. After a general introduction, three topics of current interest are briefly reviewed: binary black hole mergers, the evolution of strong gravitational waves, and shift conditions for neutron star binaries.
History of the cosmological constant
Authors: Demiański M.
Published: May 2022

General review of history of the cosmological constant problem is presented. Some theoretical ideas suggesting that Λ = 0 are mentioned and recent observational results are discussed.
Rotating bodies as boundary value problems
Authors: Neugebauer G.
Published: May 2022

There are physically interesting particular cases in which the treatment of the matter region of rotating bodies may be replaced by the formulation of boundary values along the surface of the body. In this way, rotating black holes and rotating disks of dust (“galaxies”)are described by boundary value problems which can be solved by means of the so‐called Inverse Scattering Method. Physical properties of the solutions and consequences of the approach are discussed. Among other things, the balance problem for two black holes can be tackled.
The binary black‐hole dynamics at the third post‐Newtonian order in the orbital motion
Authors: Jaranowski P. , Schäfer G.
Published: May 2022

The orbital dynamics of the binary point‐mass systems is ambiguous at the third post‐Newtonian order of approximation. The static ambiguity is known to be related to the difference between the Brill‐Lindquist solution and the Misner‐Lindquist solution of the time‐symmetric conformally flat initial value problem for binary black holes.The kinetic ambiguity is noticed to violate in general the standard relation between the center‐of‐mass velocity and the total linear momentum as demanded by global Lorentz invariance.
Factor structure of the Tomimatsu‐Sato solutions and their recurrence relations
Authors: Hoenselaers C.
Published: May 2022

We consider stationary axisymmetric vacuum solutions of Einstein's equations for which the Ernst potential is rational in prolate spheroidal coordinates. Extending an earlier study we show that there are several new expressions which are factorizable. In particular, we concentrate on the Tomimatsu‐Sato solutions and their recurrence relations. Various continuum limits of the recurrence relations will be discussed.
Cosmic phase transitions
Authors: Kämpfer B.
Published: May 2022

The sequence of phase transitions during the hot history of the universe is followed within a phenomenological framework. Particular emphasis is put on the QCD confinement transition, which is at reach under earth laboratory conditions. A tepid inflationary scenario on the GUT scale with bubble growth at moderate supercooling is discussed.
Coupled Brownian motors on a tilted washboard
Authors: Van den Broeck C. , Bena I. , Reimann P. , Lehmann J.
Published: May 2022

We consider globally coupled particles, each of them governed by a deterministic relaxation dynamics in a critically tilted washboard potential, but without a preferential spatial direction for the coupled system as a whole. For weak‐to‐moderate coupling we observe a spontaneous breaking of the system intrinsic symmetry which entails a spontaneous collective transport via a ratchet effect, possibly with a superimposed oscillatory long time behavior. For strong coupling, spontaneous symmetry breaking and spontaneous directed current are ruled out, whereas a negative mobility in response to an externally applied force is recovered.
Classical and quantum transport in deterministic Hamiltonian ratchets
Authors: Dittrich T. , Ketzmerick R. , Otto M.‐F. , Schanz H.
Published: May 2022

We study directed transport in classical and quantum area‐preserving maps, periodic in space and momentum. On the classical level, we show that a sum rule excludes directed transport of the entire phase space, leaving only the possibility of transport in (dynamically defined) subsets, such as regular islands or chaotic areas. As a working example, we construct a mapping with a mixed phase space where both the regular and the chaotic components support directed currents, but with opposite sign. The corresponding quantum system shows transport of similar strength, associated to the same subsets of phase space as in the classical map.
Kramers turnover theory for bridges
Authors: Hershkovitz Eli , Pollak Eli
Published: May 2022

The bridge length dependence of the classical transfer rate from donor to acceptor is studied for symmetric bridged systems. The reaction rate is shown to be factorizable into an escape rate from the donor well and a transmission factor through the bridge. As expected for a diffusing particle this transmission factor is inversely proportional to the bridge length, for long bridges. The Pollak‐Grabert‐Hänggi turnover theory is shown to be applicable for all friction strengths and bridge lengths studied in this paper.
Superposition and quantum measurement of trapped atoms
Authors: Wineland D.J. , Monroe C.R. , Sackett C. , Kielpinski D. , Rowe M. , Meyer V. , Itano W.
Published: May 2022

We summarize experiments at NIST on quantum‐state engineering, entanglement, quantum logic, and quantum measurement of trapped atomic ions.
The single electron transistor and artificial atoms
Authors: Kastner M.A.
Published: May 2022

Modern techniques of lithography make it possible to confine electrons to sufficiently small dimensions that the quantization of both their charge and their energy are easily observable. When such confined electrons are allowed to tunnel to metallic leads a single electron transistor (SET) is created. This transistor turns on and off again every time one electron is added to the isolated region. Whereas we can understand conventional transistors using classical concepts, the SET is quantum mechanical in an essential way. In fact, there is a close analogy between the confined electrons inside an SET and an atom. In this review, the physics underlying the operation of SETs is explained, a brief history of its invention is presented, and issues of current interest are discussed.
Particle accelerators
Authors: Schnell W.
Published: May 2022

Particle Accelerators have had a decisive influence on twentieth‐century physics. A concise description of their development – from the early 1930s till today – is given.
Atom optics: Old ideas, current technology, and new results
Authors: Pritchard D.E. , Cronin A.D. , Gupta S. , Kokorowski D.A.
Published: May 2022

Atom optics is the coherent manipulation of the atomic matter waves originally postulated by the developers of quantum mechanics. These pioneers also proposed the use of stimulated light forces to manipulate particles. These ideas have been combined with current technology to produce the field of atom optics. This, in turn, has shed new light on old quantum problems like the which way problem and the origins of quantum decoherence. Bose Einstein condensates combine naturally with atom optics to produce new results such as the coherent amplification of matter waves. This review of atom optics traces these connections.
Counting and entangling Planck's quanta with atoms in a box
Authors: Haroche S. , Brune M. , Raimond J.M.
Published: May 2022

We summarize experiments at Ecole Normale Supérieure on entanglement, quantum logic, quantum measurement and decoherence performed with photons and atoms in cavities.
Quantum architecture of novel solids
Authors: Zunger A.
Published: May 2022

The current status of our understanding of Quantum Mechanics is that if one specifies the chemical formula of a compound (e.g., CuAu, or GaAs, or NiPt) it is still impossible to predict if this material is a superconductor or not, but it is now possible to predict its crystal structure. This is a nontrivial accomplishment for there are as many as 2N possible structures for a binary compound. This article reviews this classic question of structural chemistry and condensed matter physics: How can one figure out which of the astronomic number of possible crystal structures is selected by Nature?
Formation of the universe: From classical to quantum cosmology
Authors: Nicolai H. , Pössel M.
Published: May 2022

We give a brief overview of the role of quantum theory in cosmology, reviewing the standard model of classical cosmology, inflation and quantum cosmology.
Scale invariance in the causal approach to renormalization theory
Authors: Grigore Dan R.
Published: May 2022

The dilation invariance is studied in the framework of Epstein‐Glaser approach to renormalization theory. Some analogues of the Callan‐Symanzik equations are found and they are applied to the scalar field theory and to Yang‐Mills models. We find the interesting result that, if all fields of the theory have zero masses, then from purely cohomological consideration, one can obtain the anomalous terms of logarithmic type.
Operator product expansion in local causal perturbation theory
Authors: Prange Dirk
Published: May 2022

We derive an operator product expansion in φ4‐theory for the time ordered product of two interacting fields in the Bogoliubov‐Epstein‐Glaser approach. Our result relies on the definition of an appropriate bilocal time ordered product as a generalization of the local time ordered products given by Epstein‐Glaser.
Universal Relationship of Time and Frequency in Photonic Tunnelling
Authors: Haibel A. , Nimtz G.
Published: May 2022

Tunnelling transit time for frustrated total internal reflection (FTIR) in a double‐prism experiment was measured using microwave radiation. We have found that the transit time is of the same order of magnitude as the corresponding transit time measured either in an undersized waveguide (evanescent modes) or in a photonic lattice. Moreover we have established that in all such experiments the tunnelling transit time is approximately equal to the reciprocal (1/f) of the corresponding frequency of radiation.
Some remarks on the Bel‐Robinson tensor
Authors: Garecki Janusz
Published: May 2022

In this paper we present our point of view on the correct physical interpretation of the Bel‐Robinson tensor within the framework of standard General Relativity (GR), i.e., within the framework of GR without supplementary elements like an arbitrary vector field, a distinguished tetrad field or a second metric. We show that this tensor arises as a consequence of the Bianchi identities and, in a natural manner, it is linked to the difference of the canonical gravitational energy‐momentum as calculated in normal coordinates in a small vicinity of their origin P and in the origin P.
Size of three‐dimensional objects measured by means of photoemission electron microscopy
Authors: Nepijko S.A. , Sedov N.N. , Schmidt O. , Fecher G.H. , Schönhense G.
Published: May 2022

Pb particles on a Si(111) substrate were investigated using a photoemission electron microscope (PEEM). The electrons have been excited by a linearly polarised femtosecond laser beam with a wavelength of λ = 400 nm. The PEEM images exhibit an unusually high contrast. They arise due to photoemission being of a nontrivial nature because the photon energy is lower than the work function of the sample. It may be caused by the following processes: two‐ or multi‐photon absorption, tunnel‐photoeffect induced by a strong lowering of the potential barrier owing to enhancement of the electrical field of the powerful incident light wave on a rough surface, generation of second harmonic with its following absorption, or electron gas heating. Images obtained with orthogonal directions of the photon polarisation were compared to estimate the shape of different Pb particles. The size of the islands was determined by two methods, either from the shape of the spatial brightness distribution or from the area under the curve of this distribution.
Irreducible Freedman‐Townsend vertex and Hamiltonian BRST cohomology
Authors: Bizdadea C. , Cioroianu E.M. , Saliu S.O.
Published: May 2022

The irreducible Freedman‐Townsend vertex is derived by means of the Hamiltonian deformation procedure based on local BRST cohomology.
The statistical mechanics of topological polymers: a field theorist point of view
Authors: Ferrari Franco
Published: May 2022

This is a self‐contained introduction to polymer physics and to the application of field theoretical techniques to the statistical mechanics of polymer systems. Of course, since polymer physics is a highly interdisciplinary subject, involving different disciplines like knot theory, field theory, statistical mechanics and some notions of bio‐chemistry and chemistry, it is not possible to cover all these topics in a single review. Particular emphasis is given here to the problem of describing the fluctuations of topologically linked polymers in a solution from a microscopical point of view. Some recent advances in this direction are presented. Another purpose of this work is to serve as a guide for whoever would like to apply the methods of field theory to polymers. To ease reading, technical terms have been quoted in boldface characters at the points in which their meaning is explained.
New hierarchy for the Liouville equation, irreversibility and Fokker‐Planck‐like structures
Authors: Alvarez‐Estrada R.F.
Published: May 2022

The issue of irreversibility is revisited for a closed system formed by N classical non‐relativistic particles inside a volume Ω, interacting through two‐body potentials, for large N and Ω. The classical phase‐space distribution function f, multiplied by suitable Hermite polynomials and integrated over all momenta, yields new moments. The Liouville equation and the initial distribution fin imply a new non‐equilibrium linear infinite hierarchy for the moments. That hierarchy differs from the BBGKY one for distribution functions and displays some suggestive Fokker‐Planck‐like structures. A physically motivated ansatz for fin (which introduces statistical assumptions), used by previous authors, is chosen. All moments of order n ≥ n0 are expressed in terms of those of order n0 — 1 and of fin. The properties of the Fokker‐Planck‐like structures (hermiticity, non‐negative eigenvalues) allow for implementing a natural long‐time approximation in the hierarchy, so as to introduce relaxation to equilibrium and irreversibility, consistently with the hydrodynamical balance equations. Further (more restrictive) assumptions and approximations lead to new irreversible models, generalizing non‐trivially the Fokker‐Planck equation. They are described through a truncated hierarchy of linear equations for moments of order n ≤ n0 — 1 (n0 being finite). The connections with Brownian particle dynamics and Fluid Dynamics are analyzed, for consistency.
Power spectrum of fluctuations in self‐gravitating systems in a statistical thermodynamics approach
Authors: Granovskii Y.I. , Stelmach J.
Published: May 2022

For the description of a self‐gravitating system, a closed formula is found for the power spectrum of the density fluctuations within a statistical thermodynamics approach. A key point of the calculation is the evaluation of the statistical integral describing a system of “particles” interacting gravitationally in a canonical ensemble. The power spectrum turns out to have a smoothed step‐like form. A characteristic length separates two classes of distance regimes and thus t wo phases. The almost flat part of the spectrum for small wave vectors means that there is no distinguished scale of fluctuations in the self‐gravitating system for distances larger than some characteristic length.
Spatial optical (2+1)‐dimensional scalar‐ and vector‐solitons in saturable nonlinear media
Authors: Weilnau C. , Ahles M. , Petter J. , Träger D. , Schröder J. , Denz C.
Published: May 2022

(2+1)‐dimensional optical spatial solitons have become a major field of research in nonlinear physics throughout the last decade due to their potential in adaptive optical communication technologies. With the help of photorefractive crystals that supply the required type of nonlinearity for soliton generation, we are able to demonstrate experimentally the formation, the
dynamic properties, and especially the interaction of solitary waves, which were so far only known from general soliton theory. Among the complex interaction scenarios of scalar solitons, we reveal a distinct behavior denoted as anomalous interaction, which is unique in soliton‐supporting systems. Further on, we realize highly parallel, light‐induced waveguide configurations based on photorefractive screening solitons that give rise to technical applications towards waveguide couplers and dividers as well as all‐optical information processing devices where light is controlled by light itself. Finally, we demonstrate the generation, stability and propagation dynamics of multi‐component or vector solitons, multipole transverse optical structures bearing a complex geometry. In analogy to the particle‐light dualism of scalar solitons, various types of vector solitons can ‐ in a broader sense ‐ be interpreted as molecules of light.
The metal‐insulator transitions of VO2: A band theoretical approach
Authors: Eyert V.
Published: May 2022

The results of first principles electronic structure calculations for the metallic rutile and the insulating monoclinic phase of vanadium dioxide are presented. In addition, the insulating phase is investigated for the first time. The density functional calculations allow for a consistent understanding of all three phases. In the rutile phase metallic conductivity is carried by metal orbitals, which fall into the one‐dimensional band, and the isotropically dispersing bands. Hybridization of both types of bands is weak. In the phase splitting of the band due to metal‐metal dimerization and upshift of the bands due to increased p‐d overlap lead to an effective separation of both types of bands. Despite incomplete opening of the optical band gap due to the shortcomings of the local density approximation, the metal‐insulator transition can be understood as a Peierls‐like instability of the band in an embedding background of electrons. In the phase, the metal‐insulator transition arises as a combined embedded Peierls‐like and antiferromagnetic instability. The results for VO2 fit into the general scenario of an instability of the rutile‐type transition‐metal dioxides at the beginning of the d series towards dimerization or antiferromagnetic ordering within the characteristic metal chains. This scenario was successfully applied before to MoO2 and NbO2. In the compounds, the and bands can be completely separated, which leads to the observed metal‐insulator transitions.
Quantum Hall effect in intentionally disordered two‐dimensional electron systems
Authors: Buth K. , Merkt U.
Published: May 2022

In this work intentionally disordered two‐dimensional electron systems in modulation doped GaAs/GaAlAs heterostructures are studied by magnetotransport experiments. The disorder is provided by a δ‐doped layer of negatively charged beryllium acceptors. In low magnetic fields a strong negative magnetoresistance is observed that can be ascribed to magnetic‐field‐induced delocalization. At increased magnetic fields the quantum Hall effect exhibits broad Hall plateaus whose centers are shifted to higher magnetic fields, i.e. lower filling factors. This shift can be explained by an asymmetric density of states. Consistently, the transition into the insulating state of quantum Hall droplets in high magnetic fields occurs at critical filling factors around νc=0.4, i.e. well below the value 1/2 that is expected for symmetric disorder potentials. The insulator transition is characterized by the divergence of both the longitudinal resistance as well as the Hall resistance. This is contrary to other experiments which observe a finite Hall resistance in the insulating regime and has not been observed previously. According to recent theoretical studies the divergence of the Hall resistance points to quantum coherent transport via tunneling between quantum Hall droplets. The magnetotransport experiments are supplemented by simulations of potential landscapes for random and correlated distributions of repulsive scatterers, which enable the determination of percolation thresholds, densities of states, and oscillator strengths for far‐infrared excitations. These simulations reveal that the strong shift of the Hall plateaus and the observed critical filling factor for the insulator transition in high magnetic fields require an asymmetric density of states that can only be generated by a strongly correlated beryllium distribution. Cyclotron resonance on the same samples also indicates the possibility of correlations between the beryllium acceptors.
Spin polarization transitions in the FQHE
Authors: Mariani E. , Mazzarello R. , Sassetti M. , Kramer B.
Published: May 2022

The spin polarization of the FQHE ground states at fixed filling factors is analyzed within a composite fermion model. As a function of the perpendicular magnetic field several cross‐overs between differently polarized ground states are predicted, in agreement with recent experimental investigations. The magnetic field and temperature scalings of the polarization, as well as the magnetic field dependence of the spin‐flip gap are studied.
Precise Modulation of Triple‐Phase Boundaries towards a Highly Functional Exsolved Catalyst for Dry Reforming of Methane under a Dilution‐Free System
Authors: Oh Jinkyung , Joo Sangwook , Lim Chaesung , Kim Hyung Jun , Ciucci Francesco , Wang Jian‐Qiang , Han Jeong Woo , Kim Guntae
Published: May 2022

Dry reforming of methane (DRM) has been emerging as a viable solution to achieving carbon neutrality enhanced by the Paris Agreement as it converts the greenhouse gases of CO2 and CH4 into industrially useful syngas. However, there have been limited studies on the DRM catalyst under mild operating conditions with a high dilution gas ratio due to their deactivation from carbon coking and metal sintering. Herein, we apply the triple‐phase boundary (TPB) concept to DRM catalyst via exsolution phenomenon that can secure elongated TPB by controlling the Fe‐doping ratio in perovskite oxide. Remarkably, the exsolved catalyst with prolongated TPB shows exceptional CO2 and CH4 conversion rates of 95.9 % and 91.6 %, respectively, stable for 1000 hours under a dilution‐free system. DFT calculations confirm that the Lewis acid of support and Lewis base of metal at the TPB promote the adsorption of reactants, resulting in lowering the overall CO2 dissociation and CH4 dehydrogenation energy.
Die direkte mechanokatalytische Suzuki–Miyaura‐Kupplung kleiner organischer Moleküle
Authors: Pickhardt Wilm , Beaković Claudio , Mayer Maike , Wohlgemuth Maximilian , Kraus Fabien Joel Leon , Etter Martin , Grätz Sven , Borchardt Lars
Published: May 2022

In dieser Arbeit wird die Suzuki–Miyaura‐Reaktion in Abwesenheit von Lösungsmitteln, Liganden und pulverförmiger Katalysatoren vorgestellt. Unter Verwendung einer einzelnen katalytisch aktiven Mahlkugel können quantitative Ausbeuten nach 30 min des Vermahlens isoliert werden. Weiterhin führten Anpassungen der Mahlparameter dazu, dass der Materialverlust durch Kugelabrieb vermieden wurde. Anhand dieses abriebfreien Systems wird durch Röntgenphotoelektronenspektroskopie, in situ Röntgendiffraktrometrie, sowie durch Referenzexperimente bewiesen, dass die katalytische Reaktion auf der Kugeloberfläche stattfindet. Die Vielseitigkeit dieses neuartigen Katalysekonzepts wird anhand verschiedener Edukte verdeutlicht. Aktivierte, deaktivierte, sowie sterisch‐gehinderte Aryliodide und ‐bromide werden innerhalb kurzer Zeit in guten Ausbeuten gekuppelt.
A Practical and Scalable Approach to Fluoro‐Substituted Bicyclo[1.1.1]pentanes
Authors: Bychek Roman , Mykhailiuk Pavel K.
Published: May 2022

After more than 20 years of trials, a practical scalable approach to fluoro‐substituted bicyclo[1.1.1]pentanes (F‐BCPs) has been developed. The physicochemical properties of the F‐BCPs have been studied, and the core was incorporated into the structure of the anti‐inflammatory drug Flurbiprofen in place of the fluorophenyl ring.
The Direct Mechanocatalytic Suzuki–Miyaura Reaction of Small Organic Molecules
Authors: Pickhardt Wilm , Beaković Claudio , Mayer Maike , Wohlgemuth Maximilian , Kraus Fabien Joel Leon , Etter Martin , Grätz Sven , Borchardt Lars
Published: May 2022

The molecular Suzuki cross‐coupling reaction was conducted mechanochemically, without solvents, ligands, or catalyst powders. Utilizing one catalytically active palladium milling ball, products could be formed in quantitative yield in as little as 30 min. In contrast to previous reports, the adjustment of milling parameters led to the complete elimination of abrasion from the catalyst ball, thus enabling the first reported systematic catalyst analysis. XPS, in situ XRD, and reference experiments provided evidence that the milling ball surface was the location of the catalysis, allowing a mechanism to be proposed. The versatility of the approach was demonstrated by extending the substrate scope to deactivated and even sterically hindered aryl iodides and bromides.
Ultrathin Covalent Organic Framework Anchored on Graphene for Enhanced Organic Pollutant Removal
Authors: Li Changxia , Guggenberger Patrick , Han Seung Won , Ding Wei‐Lu , Kleitz Freddy
Published: May 2022

Covalent organic frameworks (COFs) are of great potential as adsorbents owing to their tailorable functionalities, low density and high porosity. However, their intrinsically stacked two‐dimensional (2D) structure limits the full use of their complete surface for sorption, especially the internal pores. The construction of ultrathin COFs could increase the exposure of active sites to the targeted molecules in a pollutant environment. Herein, an ultrathin COF with a uniform thickness of ca. 2 nm is prepared employing graphene as the surface template. The resulting hybrid aerogel with an ultralow density (7.1 mg cm−3) exhibits the ability to remove organic dye molecules of different sizes with high efficiency. The three‐dimensional (3D) macroporous structure and well‐exposed adsorption sites permit rapid diffusion of solution and efficient adsorption of organic pollutants, thereby, greatly contributing to its enhanced uptake capacity. This work highlights the effect of COF layer thickness on adsorption performance.
Comprehensive demetallization of crude oil using spherical polyelectrolyte brushes with submicron polybutadiene latex as a core
Authors: Yang Lianzhou , Shen Kaili , Xu Jun , Ren Mannian , Cao Fahai
Published: May 2022

Stable oil‐soluble metals complexes in crude oil bring various problems to the oil processing. In the previous work, four spherical polymer brushes with SiO2 as a core showed high nickel and calcium removal efficiency, but SiO2 has high density and smaller specific surface area, greatly limiting the demetallization efficiency. In the present work, spherical polyelectrolyte brushes (PAA@PB) were synthesized by emulsion grafting polymerization. DLS and TEM show that PAA@PB exhibits a uniform spherical core‐shell structure with a diameter of 526.3 nm, and TGA exhibits that the grafting rate is 20.6%. The demetallization rate and selectivity of PAA@PB were investigated with varying concentration, electrical desalination conditions, pH value, and NaCl concentration. In contrast, the demetallization efficiency of PAA@PB is much greater than that of PAA@SiO2‐G. Notably, PAA@PB exhibits excellent nickel removal efficiency, but a little more selective for iron. The optimal removal rate for calcium, nickel, and iron are 55.3%, 52.6%, and 46.1%, respectively. Compared with P4VP@SiO2‐G, which possesses the highest demetallization efficiency among four polymer brushes with SiO2, to achieve the same nickel removal rate, the concentration of PAA@PB is almost eight times less than that of P4VP@SiO2‐G. Consequently, PAA@PB has great potential as an excellent comprehensive demetallization agent.
Choroid Plexus–Infiltrating T Cells as Drivers of Murine Neuropsychiatric Lupus
Authors: Moore Erica , Huang Michelle W. , Reynolds Cara A. , Macian Fernando , Putterman Chaim
Published: May 2022

Objective

T cells are critical in the pathogenesis of systemic lupus erythematosus (SLE) in that they secrete inflammatory cytokines, help autoantibody production, and form autoreactive memory T cells. Although the contribution of T cells to several forms of organ‐mediated damage in SLE has been previously demonstrated, the role of T cells in neuropsychiatric SLE (NPSLE), which involves diffuse central nervous system manifestations and is observed in 20–40% of SLE patients, is not known. Therefore, we conducted this study to evaluate how behavioral deficits are altered after depletion or transfer of T cells, to directly assess the role of T cells in NPSLE.

Methods

MRL/lpr mice, an NPSLE mouse model, were either systemically depleted of CD4+ T cells or intracerebroventricularly injected with choroid plexus (CP)–infiltrating T cells and subsequently evaluated for alterations in neuropsychiatric manifestations. Our study end points included evaluation of systemic disease and assessment of central nervous system changes.

Results

Systemic depletion of CD4+ T cells ameliorated systemic disease and cognitive deficits. Intracerebroventricular injection of CP–infiltrating T cells exacerbated depressive‐like behavior and worsened cognition in recipient mice compared with mice who received injection of splenic lupus T cells or phosphate buffered saline. Moreover, we observed enhanced activation in CP–infiltrating T cells when cocultured with brain lysate–pulsed dendritic cells in comparison to the activation levels observed in cocultures with splenic T cells.

Conclusion

T cells, and more specifically CP–infiltrating antigen‐specific T cells, contributed to the pathogenesis of NPSLE in mice, indicating that, in the development of more targeted treatments for NPSLE, modulation of T cells may represent a potential therapeutic strategy.