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Institution

University of Stuttgart

EducationStuttgart, Germany
About: University of Stuttgart is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Laser & Finite element method. The organization has 27715 authors who have published 56370 publications receiving 1363382 citations. The organization is also known as: Universität Stuttgart.


Papers
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Journal ArticleDOI
18 Sep 2008-Nature
TL;DR: P polarized neutron diffraction is used to demonstrate for the model superconductor HgBa2CuO4+δ (Hg1201) that the characteristic temperature T* marks the onset of an unusual magnetic order, a demonstration of the universal existence of such a state.
Abstract: The pseudogap region of the phase diagram is an important unsolved puzzle in the field of high transition-temperature superconductivity. Li et al. report polarized neutron diffraction data that demonstrate that the characteristic temperature, T*, marks the onset of an unusual magnetic order, and hence a novel state of matter with broken time-reversal symmetry, for the model superconductor HgBa2CuO4+δ (Hg1201). The findings appear to rule out theories that regard T* as a crossover temperature rather than a phase transition temperature. Instead, they are consistent with the notion that many of the unusual properties arise from the presence of a quantum-critical point. The pseudogap region of the phase diagram is an important unsolved puzzle in the field of high-transition-temperature (high-Tc) superconductivity, characterized by anomalous physical properties1,2. There are open questions about the number of distinct phases and the possible presence of a quantum-critical point underneath the superconducting dome3,4,5. The picture has remained unclear because there has not been conclusive evidence for a new type of order. Neutron scattering measurements for YBa2Cu3O6+δ (YBCO) resulted in contradictory claims of no6,7 and weak8,9 magnetic order, and the interpretation of muon spin relaxation measurements on YBCO10,11 and of circularly polarized photoemission experiments on Bi2Sr2CaCu2O8+δ(refs 12, 13) has been controversial. Here we use polarized neutron diffraction to demonstrate for the model superconductor HgBa2CuO4+δ (Hg1201) that the characteristic temperature T* marks the onset of an unusual magnetic order. Together with recent results for YBCO14,15, this observation constitutes a demonstration of the universal existence of such a state. The findings appear to rule out theories that regard T* as a crossover temperature16,17,18 rather than a phase transition temperature19,20,21. Instead, they are consistent with a variant of previously proposed charge-current-loop order19,20 that involves apical oxygen orbitals22, and with the notion that many of the unusual properties arise from the presence of a quantum-critical point3,4,5,19.

229 citations

Journal ArticleDOI
TL;DR: In this article, semi-empirical pseudopotentials are used in calculating the ground-state potentials curves for single valence-electron molecular ions, and very accurate results are obtained and a number of predictions given.

229 citations

Journal ArticleDOI
TL;DR: In this article, a collection of short articles written by experts in thermal spray who were asked to present a snapshot of the current state of their specific field, give their views on current challenges faced by the field and provide some guidance as to the R&D required to meet these challenges.
Abstract: Considerable progress has been made over the last decades in thermal spray technologies, practices and applications. However, like other technologies, they have to continuously evolve to meet new problems and market requirements. This article aims to identify the current challenges limiting the evolution of these technologies and to propose research directions and priorities to meet these challenges. It was prepared on the basis of a collection of short articles written by experts in thermal spray who were asked to present a snapshot of the current state of their specific field, give their views on current challenges faced by the field and provide some guidance as to the R&D required to meet these challenges. The article is divided in three sections that deal with the emerging thermal spray processes, coating properties and function, and biomedical, electronic, aerospace and energy generation applications.

229 citations

Journal ArticleDOI
TL;DR: An artificial system of reactive magnetic micropropellers that mimic the bacterium Helicobacter pylori's strategy to move through gastric mucin gels by making use of surface-immobilized urease is presented, demonstrating the validity of this biomimetic approach to penetrate biological gels and suggesting that such particles could potentially penetrate native mucus.
Abstract: In the body, mucus provides an important defense mechanism by limiting the penetration of pathogens. It is therefore also a major obstacle for the efficient delivery of particle-based drug carriers. The acidic stomach lining in particular is difficult to overcome because mucin glycoproteins form viscoelastic gels under acidic conditions. The bacterium Helicobacter pylori has developed a strategy to overcome the mucus barrier by producing the enzyme urease, which locally raises the pH and consequently liquefies the mucus. This allows the bacteria to swim through mucus and to reach the epithelial surface. We present an artificial system of reactive magnetic micropropellers that mimic this strategy to move through gastric mucin gels by making use of surface-immobilized urease. The results demonstrate the validity of this biomimetic approach to penetrate biological gels, and show that externally propelled microstructures can actively and reversibly manipulate the physical state of their surroundings, suggesting that such particles could potentially penetrate native mucus.

229 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the state of the art on the structure of amorphous silicon monoxide (SiO) using diffraction, microscopy, spectroscopy, and magnetometry methods.
Abstract: The present state of research on the structure of amorphous silicon monoxide (SiO) is reviewed. The black, coal-like modification of bulk SiO is studied by a combination of diffraction, microscopy, spectroscopy, and magnetometry methods. Partial radial distribution functions of SiO are obtained by X-ray, neutron and electron diffraction. Disproportionation of SiO into Si and SiO2 is verified. High resolution TEM gives an upper limit of less than 2 nm for the typical Si cluster size. The Si K-edge electron energy-loss near-edge structure (ELNES) data of SiO are interpreted in terms of the oxidation states Si4+ and Si0. X-ray photoelectron spectroscopy gives first details about possible stoichiometric inhomogeneities related to internal interfaces. The wipe-out effect in the 29Si MAS NMR signal of SiO is confirmed experimentally. The new estimation of the wipe-out radius is about 1.1 nm. First-time W-band, Q-band, and X-band ESR and SQUID measurements indicate an interfacial defect structure. Frequency distributions of atomic nearest-neighbours are derived. The interface clusters mixture model (ICM model) suggested here describes the SiO structure as a disproportionation in the initial state. The model implies clusters of silicon dioxide and clusters of silicon surrounded by a sub-oxide matrix that is comparable to the well-known thin Si/SiO2 interface and significant in the volume because of small cluster sizes.

229 citations


Authors

Showing all 28043 results

NameH-indexPapersCitations
Yi Chen2174342293080
Robert J. Lefkowitz214860147995
Michael Kramer1671713127224
Andrew G. Clark140823123333
Stephen D. Walter11251357012
Fedor Jelezko10341342616
Ulrich Gösele10260346223
Dirk Helbing10164256810
Ioan Pop101137047540
Niyazi Serdar Sariciftci9959154055
Matthias Komm9983243275
Hans-Joachim Werner9831748508
Richard R. Ernst9635253100
Xiaoming Sun9638247153
Feng Chen95213853881
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023147
2022482
20212,588
20202,646
20192,654
20182,525