bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semi‐classical description of ionic and electronic dynamics in metal clusters
Authors: Giglio E. , Suraud E. , Reinhard P.‐G. 
Published: May 2022

AbstractWe present a selfconsistent semi‐classical description of metal clusters with explicit ionic background. We show in particular how the flexibility of the Husimi picture allows a proper, self contained, description of ground state as well as dynamical properties of metal clusters. This leads to a coupled electrons + ions molecular dynamics, which may be followed over long times (typically one picosecond). We consider real time dynamics for electrons at a Vlasov‐LDA level and include dynamical correlations by an Ühling‐Uhlenbeck collision term (VUU). We discuss the effect of the Husimi representation on the electronic dynamics and the impact of a constant isotropic differential cross‐section in the UU collision term, as compared to a velocity dependent anisotropic differential cross section. Finally, we show that the VUU approach is capable of curing the artificial dissipation of an initial fermionic distribution function towards a classical Boltzmann equilibrium over long times.
Quantized superfields
Authors: Constantinescu Florin , Gut Markus , Scharf Günter 
Published: May 2022

AbstractWe construct quantized free superfields and represent them as operator‐valued distributions in Fock space starting with the Majorana field. We then analyse the algebras generated by free component quantum fields together with the Susy generators Q, . This enables us to obtain the quantized chiral superfield by finite Susy transformation from its scalar component. To get hermitian superfields we study by the same method a second scalar field algebra from which various scalar superfields can be obtained by exponentiation. Next we investigate the vector algebra and use it to construct the massive vector superfield. Surprisingly enough, the result is totally different from the vector multiplet in the literature. It contains two hermitian four‐vector components instead of one and a spin‐3/2 field similar to the gravitino in supergravity.
Resolution of an emission electron microscope in the presence of magnetic fields on the object
Authors: Nepijko S.A. , Sedov N.N. , Schönhense G. , Muschiol U. , Schneider C.M. , Zennaro S. , Zema N. 
Published: May 2022

AbstractThe known Brüche‐Recknagel formula for determining the resolving power of an emission electron microscope (EEM) was derived assuming idealized conditions: the object surface was planar, and the accelerating electric field was homogeneous. However, deviations from these conditions will deteriorate the resolving power. This can be caused by a surface topography as well as local electric or magnetic fields on the object surface. In the present paper the resolving power of an EEM is calculated for the case when there are local magnetic fields on the object surface. The deterioration of the resolving power will then depend on the local field strength not only in the given point of the object surface, but also in adjacent regions. The estimations performed show that the lateral resolution in EEM under the influence of magnetic microfields of real ferromagnets can be several times worse than in the case of the absence of these fields.
Noncommutative geometry and fundamental interactions: the first ten years
Authors: Gracia‐Bondía J.M. 
Published: May 2022

AbstractThis is the full text of a survey talk for nonspecialists, delivered at the 66th Annual Meeting of the German Physical Society in Leipzig, March 2002. We have not taken pains to suppress the colloquial style. References are given only insofar as they help to underline the points made; this is not a full‐blooded survey. The connection between noncommutative field theory and string theory is mentioned, but deemphasized. Contributions to noncommutative geometry made in Germany are emphasized.
Coated conductors containing grains with big aspect ratios
Authors: Leitenmeier S. , Bielefeldt H. , Hammerl G. , Schmehl A. , Schneider C.W. , Mannhart J. 
Published: May 2022

AbstractIt is shown that the critical currents of high‐Tcsuperconducting tapes fabricated by the coated conductor technologies are enhanced considerably if grain arrangements with large effective grain boundary areas are used. Increasing the aspect ratios of the grains reduces the deleterious effects of the grain boundaries. A practical road to competitive high‐Tccables is proposed.
Linear differential equations for the one‐dimensional scattering problem
Authors: Sedrakian D.M. , Khachatrian A.Z. 
Published: May 2022

AbstractThe transmission and reflection amplitudes of an electron moving in a one dimensional potential of arbitrary form are obtained using the transfer matrix method. It is shown that the one‐dimensional scattering problem, in its most general form, can be reduced to Cauchy problem for a set of two linear differential equations.
Black holes: a physical route to the Kerr metric
Authors: Meinel R. 
Published: May 2022

AbstractAs a consequence of Birkhoff's theorem, the exterior gravitational field of a spherically symmetric star or black hole is always given by the Schwarzschild metric. In contrast, the exterior gravitational field of a rotating (axisymmetric) star differs, in general, from the Kerr metric, which describes a stationary, rotating black hole. In this paper I discuss the possibility of a quasi–stationary transition from rotating equilibrium configurations of normal matter to rotating bla ck holes.
Length measurement in accelerated systems
Authors: Mashhoon B. , Muench U. 
Published: May 2022

AbstractWe investigate the limitations of length measurements by accelerated observers in Minkowski spacetime brought about via the hypothesis of locality, namely, the assumption that an accelerated observer at each instant is equivalent to an otherwise identical momentarily comoving inertial observer. We find that consistency can be achieved only in a rather limited neighborhood around the observer with linear dimensions that are negligibly small compared to the characteristic acceleration length of the observer.
Linear pre‐metric electrodynamics and deduction of the light cone
Authors: Rubilar G.F. 
Published: May 2022

AbstractWe formulate a general framework for describing the electromagnetic properties of spacetime. These properties are encoded in the ‘constitutive tensor of the vacuum’, a quantity analogous to that used in the description of material media. We give a generally covariant derivation of the Fresnel equation describing the local properties of the propagation of electromagnetic waves for the case of the most general possible linear constitutive tensor. We also study the particular case in which a light cone structure is induced and the circumstances under which such a structure emerges. In particular, we will study the relationship between the dual operators defined by the constitutive tensor under certain conditions and the existence of a conformal metric. Closure and symmetry of the constitutive tensor will be found as conditions which ensure the existence of a conformal metric. We will also see how the metric components can be explicitly deduced from the constitutive tensor if these two conditions are met. Finally, we will apply the same method to explore the consequences of relaxing the condition of symmetry and how this affects the emergence of the light cone.
Quantum spin chains with various defects
Authors: Schuster C. , Eckern U. 
Published: May 2022

AbstractUsing the density matrix renormalization group (DMRG) method, we study the quantum coherence in one‐dimensional disordered spin chains and Fermi systems. We consider in detail spinless fermions on a ring, and compare the influence of several kinds of impurities in a gapless and a dimerized, gapped system. In the translation‐invariant system a so‐called site‐impurity, which can be realized by a local potential or a modification of one link, increases for repulsive interaction, and decreases for attractive interaction, upon renormalization. The weakening of two neighbouring bonds, which is a realization of a so‐called bond‐impurity, on the other hand, is healed for repulsive interaction, but enhanced for intermediate attractive interactions. This leads to a strong suppression of the quantum coherence measured by the phase sensitivity, but not to localization. Adding a local distortion to a dimerized system, we find that even the presence of a single site‐impurity increases the metallic region found in the dimerized model. For a strong dimerization and a high barrier, an additional sharp maximum, is seen in the phase sensitivity as a function of interaction, already for systems with about 100 sites. A bond‐impurity in the dimerized system also opens a small metallic window in the otherwise isolating regime.
Traversal time for Dirac particles through a potential barrier
Authors: Li C‐F. , Chen X. 
Published: May 2022

AbstractA traversal time that has no problem of superluminality was advanced for particles to tunnel through potential barriers in the non‐relativistic quantum theory in a previous paper by C.‐F. Li and Q. Wang, Physica B 296 (2001) 356. This time is generalized in this paper to Dirac's relativistic quantum theory. Both evanescent and propagating cases are considered. It is shown that the traversal time in the evanescent case has much the same properties as in the non‐relativistic quantum theory and thus has no problem of superluminality. It also gets rid of the problem of superluminality in the propagating case. Comparisons with the dwell time, the group delay, and the velocity of monochromatic front are also made.
Intramolecular Energy and Solvent‐Dependent Chirality Transfer within a BINOL‐Perylene Hetero‐Cyclophane
Authors: Ouyang Guanghui , Rühe Jessica , Zhang Yang , Lin Mei‐Jin , Liu Minghua , Würthner Frank 
Published: May 2022

AbstractMultichromophoric macrocycles and cyclophanes are important supramolecular architectures for the elucidation of interchromophoric interactions originating from precise spatial organization. Herein, by combining an axially chiral binaphthol bisimide (BBI) and a bay‐substituted conformationally labile twisted perylene bisimide (PBI) within a cyclophane of well‐defined geometry, we report a chiral PBI hetero‐cyclophane (BBI‐PBI) that shows intramolecular energy and solvent‐regulated chirality transfer from the BBI to the PBI subunit. Excellent spectral overlap and spatial arrangement of BBI and PBI lead to efficient excitation energy transfer and subsequent PBI emission with high quantum yield (80–98 %) in various solvents. In contrast, chirality transfer is strongly dependent on the respective solvent as revealed by circular dichroism (CD) spectroscopy. The combination of energy and chirality transfer affords a bright red circularly polarized luminescence (CPL) from the PBI chromophore by excitation of BBI.
Asymmetrically Doping a Platinum Atom into a Au38 Nanocluster for Changing the Electron Configuration and Reactivity in Electrocatalysis
Authors: Liu Xu , Wang Endong , Zhou Meng , Wan Yan , Zhang Yuankun , Liu Haoqi , Zhao Yue , Li Jin , Gao Yi , Zhu Yan 
Published: May 2022

AbstractIt is an obstacle to precisely manipulate a doped heteroatom into a desired position in a metal nanocluster. Herein, we overcome this difficulty to obtain Pt1Au37(SCH2PhtBu)24 and Pt2Au36(SCH2PhtBu)24 nanoclusters via controllably doping Pt atoms into the kernels of Au38(SCH2PhtBu)24. We reveal that asymmetrical doping of one Pt atom into either of the cores of Au38(SCH2PhtBu)24 elevates the relative energy of the HOMO (highest occupied molecular orbital) accompanied by one valence electron loss of Pt1Au37(SCH2PhtBu)24, compared to Au38(SCH2PhtBu)24 with 14 electrons, while symmetrical doping of two Pt atoms into the cores of Au38(SCH2PhtBu)24 narrows the HOMO–LUMO gap (LUMO: lowest unoccupied molecular orbital) of Pt2Au36(SCH2PhtBu)24 with two valence electrons less. Consequently, Pt1Au37(SCH2PhtBu)24 shows an electron‐spin‐induced high activity for CO2 electroreduction, whereas Pt2Au36(SCH2PhtBu)24 is least efficient and Au38(SCH2PhtBu)24 has a decent performance.
Highly Selective Carbonylation of CH3Cl to Acetic Acid Catalyzed by Pyridine‐Treated MOR Zeolite
Authors: Fang Xudong , Wen Fuli , Ding Xiangnong , Liu Hanbang , Chen Zhiyang , Liu Zhaopeng , Liu Hongchao , Zhu Wenliang , Liu Zhongmin 
Published: May 2022

AbstractThe selective conversion of methane to high value‐added chemicals under mild conditions is of great significance for the commercially viable and sustainable utilization of methane but remains a formidable challenge. Herein, we report a strategy for efficiently converting methane to acetic acid via CH3Cl as an intermediate. Up to 99.3 % acetic acid and methyl acetate (AA+MA) selectivity was achieved over pyridine‐pretreated MOR (MOR‐8) under moderate conditions of 523 K and 2.0 MPa. Water, conventionally detrimental to carbonylation reaction over zeolite catalysts, was conducive to the production of AA in the current reaction system. In the 100 h continuous test with the MOR‐8 catalyst, the average AA+MA selectivity remained over 98 %. AA was formed by carbonylation of methoxy groups within 8‐membered rings of MOR followed by hydrolysis. This strategy provided an approach for highly efficient utilization of methane to oxygenates under mild reaction conditions.
Ru–Co Pair Sites Catalyst Boosts the Energetics for the Oxygen Evolution Reaction
Authors: Zheng Xiaobo , Yang Jiarui , Xu Zhongfei , Wang Qishun , Wu Jiabin , Zhang Erhuan , Dou Shixue , Sun Wenping , Wang Dingsheng , Li Yadong 
Published: May 2022

AbstractManipulating the coordination environment of the active center via anion modulation to reveal tailored activity and selectivity has been widely achieved, especially for carbon‐based single‐atom site catalysts (SACs). However, tuning ligand fields of the active center by single‐site metal cation regulation and identifying the effects on the resulting electronic configuration is seldom explored. Herein, we propose a single‐site Ru cation coordination strategy to engineer the electronic properties by constructing a Ru/LiCoO2 SAC with atomically dispersed Ru−Co pair sites. Benefitting from the strong electronic coupling between Ru and Co sites, the catalyst possesses an enhanced electrical conductivity and achieves near‐optimal oxygen adsorption energies. Therefore, the optimized catalyst delivers superior oxygen evolution reaction (OER) activity with low overpotential, the high mass activity of 1000 A goxide−1 at a small overpotential of 335 mV, and excellent long‐term stability. It also exhibits rapid kinetics with superior rate capability and outstanding durability in a zinc–air battery.
Effects of glyphosate on the growth, development, and physiological functions of silkworm, Bombyx mori
Authors: Feng Piao , Dai Minli , Yang Jin , Wang Yuanfei , Mao Tingting , Su Wujie , Li Fanchi , Sun Haina , Wei Jing , Li Bing 
Published: May 2022

AbstractGlyphosate is an herbicide widely used worldwide, but whether it is safe to nontarget organisms is controversial. In this study, the lepidopteran model insect silkworm was used to investigate the effects of glyphosate residues. The LC50 (72 h) of glyphosate on silkworm was determined to be 14875.98 mg/L, and after exposure to glyphosate at 2975.20 mg/L (a concentration comparable to that used for weed control in mulberry fields), silkworm growth was inhibited by 9.00%, total cocoon weight was lowered by 10.53%, feed digestibility was decreased by 7.56%, and the activities of alpha‐amylase and trypsin were reduced by 10.41% and 21.32%, respectively. Pathological analysis revealed that glyphosate exposure led to significantly damaged midgut, along with thinner basal layer, shedding microvilli, blurred cytoplasmic membrane, and appearance of vacuoles. Exposure to glyphosate also led to accumulation of peroxides in the intestinal tissue; the messenger RNA transcription of SOD, Cu/Zn‐SOD, and Mn‐SOD was all significantly upregulated by glyphosate treatment for 24 h, while CAT transcription was increased at 24, 48, and 72 h. The activity of SOD was increased significantly at 24 h, while significant activity changes were observed for CAT at 72 and 96 h. These results indicated that exposure to glyphosate caused oxidative stress in the midgut of silkworm and affected the midgut's physiological function. This study provides important insights in evaluating the impact of glyphosate residues in the environment on nontarget organisms.
Double Thia/sulfone[7]helicenes with Controlled Photophysical and Chiroptical Properties by Heteroatom Variation
Authors: Zhou Long , Liu Haoliang , Tan Jingyun , Liu Chao , Cao Xiao‐Yu , Narita Akimitsu , Hu Yunbin 
Published: May 2022

AbstractThe development of helicenes with strong chiroptical response and controlled photophysics is highly desirable but challenging. In this work, double thia/sulfone[7]helicenes were synthesized to investigate the heteroatom effect on the photophysical and chiroptical properties of double heterohelicenes through comparison with the previously reported double oxa[7]helicene. By variation of the embedded heteroatoms from oxygen to sulfur, the absorption and emission were significantly red‐shifted, along with the improved luminescence dissymmetry factor (glum). In particular, the double sulfone[7]helicene exhibited strong red to near‐infrared (NIR) emission withglumof 1.1×10−3, suggesting its potential as a NIR circularly polarized luminescence emitter.
Characterization of chromospheric activity based on Sun‐as‐a‐star spectral and disk‐resolved activity indices
Authors: Dineva Ekaterina , Pearson Jeniveve , Ilyin Ilya , Verma Meetu , Diercke Andrea , Strassmeier Klaus G. , Denker Carsten 
Published: May 2022

AbstractThe strong chromospheric absorption lines Ca ii H & K are tightly connected to stellar surface magnetic fields. Only for the Sun, spectral activity indices can be related to evolving magnetic features on the solar disk. The Solar Disk‐Integrated (SDI) telescope feeds the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) of the Large Binocular Telescope (LBT) at Mt. Graham International Observatory, Arizona, U.S.A. We present high‐resolution, high‐fidelity spectra that were recorded on 184 & 82 days in 2018 & 2019 and derive the Ca ii H & K emission ratio, that is, the S‐index. In addition, we compile excess brightness and area indices based on full‐disk Ca ii K‐line‐core filtergrams of the Chromospheric Telescope (ChroTel) at Observatorio del Teide, Tenerife, Spain and full‐disk ultraviolet (UV) 1600 Å images of the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). Thus, Sun‐as‐a‐star spectral indices are related to their counterparts derived from resolved images of the solar chromosphere. All indices display signatures of rotational modulation, even during the very low magnetic activity in the minimum of Solar Cycle 24. Bringing together different types of activity indices has the potential to join disparate chromospheric datasets yielding a comprehensive description of chromospheric activity across many solar cycles.
Restriction of intraflagellar transport to some microtubule doublets: An opportunity for cilia diversification?
Authors: Mallet Adeline , Bastin Philippe 
Published: May 2022

AbstractCilia are unique eukaryotic organelles and exhibit remarkable conservation across evolution. Nevertheless, very different types of configurations are encountered, raising the question of their evolution. Cilia are constructed by intraflagellar transport (IFT), the movement of large protein complexes or trains that deliver cilia components to the distal tip for assembly. Recent data revealed that IFT trains are restricted to some but not all nine doublet microtubules in the protist Trypanosoma brucei. Here, we propose that restricted positioning of IFT trains could offer potent options for cilia to evolve towards more complex (addition of new structural elements like in spermatozoa) or simpler configuration (loss of some elements like in primary cilia), and therefore be a driver of cilia diversification. We present two hypotheses to explain how IFT trains could be restricted to some doublets, either by a triage process taking place at the basal body level or by the development of molecular differences between ciliary microtubules.
High‐throughput UPLC‐Q‐TOF‐MS/MS coupled with multivariable data processing approach for the rapid screening and characterization of chemical constituents and potential bioactive compounds from Danggui Shaoyao San
Authors: Li Na , Yu Yongzhou , Cui Xiaoyan , Liu Qi , Xiong Hui 
Published: May 2022

AbstractDanggui Shaoyao San (DSS), a herbal formula, has been widely used for decades in China to treat senile dementia and dysmenorrhea. Here, an integrative high‐throughput UPLC‐Q‐TOF‐MS/MS method coupled with a multivariable data processing approach was established for rapidly screening and identifying chemical constituents and potential bioactive compounds from DSS. Through the comparison with mass fragment ions, relevant literature, and in‐house reference material database coupled with MS cleavage mechanism, 150 chemical constituents, mainly including triterpenoids, flavonoids, phathalides, and organic acids, were tentatively characterized. Most of them were identified for the first time. Then, principal component analysis was used to evaluate the differences in chemical profiles between groups, whereas the variable importance of the projection (VIP) spectrum (VIP > 1) and the trend plot of orthogonal partial least squares discriminant analysis were applied to intuitively screen the candidate variables present only in the dosed group. Consequently, by comparison with all the characterized components in vitro, 23 potential bioactive compounds were successfully identified, comprising 5 triterpenoids, 4 phathalides, 4 flavonoids, 4 organic acids, 3 lactones, and 3 other compounds, which were present in various medicinal materials, reflecting a synergistic mechanism. This work developed a rapid, reliable, and robust approach for comprehensive characterization of the chemical components and potential bioactive compounds of DSS, providing solid data for further research on pharmacodynamic substances and pharmacological mechanisms of DSS.