Local Symmetry and Domain Patterns: Ordering Phenomena in Transition-Metal Oxides

Transition-metal oxides (TMOs) show rich phase diagrams with various magnetic and electronic phases that arise from the complex interplay between spin, charge, orbital, and lattice degrees of freedom. The most prominent class of materials, which has attracted a lot of attention in the last decades, are probably high-temperature superconductors (HTS), in which the resitivity drops to zero below a critical temperature. Further examples are different kind of complex ordering phenomena, for example a modulation of the charge, spin or orbital density. In some systems a coexistence of energetically close phases is found. X-ray diffraction experiments are sensitive to a periodic arrangement of an electron-density modulation. If tuned to an absorption edge of one of the contained elements, a virtual transition from the core states to the valence states probes the occupation of the intermediate state and makes the process spectroscopically sensitive to the scattering center. Many of the interesting x-ray absorption edges of TMOs are in the energy interval between 400 and 3000 eV, in which also the absorption in air is strong. In Chap. 2 we report about commissioning and building up a novel ultar-high vacuum (UHV) diffractometer for soft x-ray diffraction experiments, which is meant as an user endstation at P04 beamline of the new synchrotron facility PETRA III. The instrument is based on a sufficiently large vacuum chamber with two differentially pumped rotary feedthroughs for an independent sample and detector rotation. The large detector circle allows to use complex detector setups, like an in-vacuum CCD and polarization analyzer. Therefore, the diffractometer is well suited for new techniques of gaining importance, like coherent x-ray diffraction (CXD), in which the finestructure of a diffraction reflex reveals information about the domain-wall dynamics, and like resonant soft x-ray diffraction (RSXD), which shows its full power when combined with a polarization analysis of the diffracted photons. In first experiments at DESY, BESSY II, and FLASH, the new machine has been successfully operated and helped to obtain data in unprecedented precision. Data recorded from multilayer reflectors, which will be used for the setup of the new polarization analyzer, and data that were recorded with the new CCD detector are presented in this chapter as well. Further data, from a RSXD experiment on magnetite are presented in Chap. 4. In Chap. 3 we report about a moderately surface-sensitive RSXD experiment in which for the first time charge stripe order in the proto-typical HTS La1.88Sr0.12CuO4 (LSCO) was found. The strong similarity of the resonant diffraction spectra from the charge order reflex in LSCO to those from an La1.48Nd0.4Sr0.12CuO4(LNSCO) reference sample, in which the existence of charge stripe order is well established, clearly shows the similar electronic origin. While charge stripe peaks were found in all LSCO samples that were studied, including in-situ cleaved and ex-situ polished ones, we could not find a reflex with bulk-sensitive hard x-ray diffraction experiments. From this we conclude that LSCO is close to the formation of a charge stripe order that already the reduced dimensionality in the near-surface region is sufficient to stabilize them in a layer of at least 5 nm thickness. In Chap. 4 we present a RSXD experiment from the (0 0 1/2) charge-orbital order reflex in Fe3O4. The azimuthal dependence of the linear dichroism shows a low-symmetry pattern, which reflects a strong monoclinic symmetry of the electronic3dwave func-tion. We found this monoclinic deviation prior to the refinements from the pseudo-orthorhombic to the monoclinic crystal structure, which was published this year. From the orbital ordering models that were proposed so far only a calculation, which is based on a complex-coefficient orbital ordering, could predict our experiment correctly. This theory further predicts a circular dichroism in the diffraction signal, which we indeed found in our experiment. In Chap. 5 we report about our results of CXD experiments on doped titanates, in which a coexistence of charge-ordered insulating an metallic regions was found. Charge ordered regions are characterized by superstructure reflections. Coherent illumination of these regions allows to produce an interference pattern that reflects information on the spatial arrangement of the insulating regions. The temporal evolution of this pattern provides insight into the dynamics due to domain reorganizations and domain-wall movements. First experiments at the ESRF and BESSY II were seriously limited due to the lacking stability of the sample setup. CXD experiments at BESSY II and PETRA III with a new sample setup, which was developed in cooperation with the University of Amsterdam, have shown that domain-wall dynamics take place on even shorter time scales than accessible. RSXD and CXD are powerful tools to study various properties of TMOs, ranging from the local electronicdwave symmetry in magnetite to the reorganization of mesoscopic domains. The new UHV diffractometer will allow to perform these kind of experiments with high precision and modern detector setups. --- This dissertation contains reprints of figures with permission from the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society

Construction of wedge-local nets of observables through Longo-Witten endomorphisms. II

In the first part, we have constructed several families of interacting wedge-local nets of von Neumann algebras. In particular, there has been discovered a family of models based on the endomorphisms of the U(1)-current algebra of Longo-Witten. In this second part, we further investigate endomorphisms and interacting models. The key ingredient is the free massless fermionic net, which contains the U(1)-current net as the fixed point subnet with respect to the U(1) gauge action. Through the restriction to the subnet, we construct a new family of Longo-Witten endomorphisms on the U(1)-current net and accordingly interacting wedge-local nets in two-dimensional spacetime. The U(1)-current net admits the structure of particle numbers and the S-matrices of the models constructed here do mix the spaces with different particle numbers of the bosonic Fock space.Comment: 33 pages, 1 tikz figure. The final version is available under Open Access. CC-B

Life cycle assessment of sodium-ion batteries

Sodium-ion batteries are emerging as potential alternatives to lithium-ion batteries. This study presents a prospective life cycle assessment for the production of a sodium-ion battery with a layered transition metal oxide as a positive electrode material and hard carbon as a negative electrode material on the battery component level. The complete and transparent inventory data are disclosed, which can easily be used as a basis for future environmental assessments. Na-ion batteries are found to be promising under environmental aspects, showing, per kWh of storage capacity, environmental impacts at the lower end of the range published for current Li-ion batteries. Still significant improvement potential is given, especially by reducing the environmental impacts associated with the hard carbon production for the anode and by reducing the nickel content in the cathode active material. For the hard carbons, the use of organic waste can be considered to be promising in this regard. Nevertheless, when looking at the energy storage capacity over lifetime, achieving a high cycle life and good charge–discharge efficiency is fundamental. This represents the main challenge especially when competing with LFP–LTO type Li-Ion batteries, which already show extraordinarily long lifetimes

Emissionsvermeidung oder Anpassung an den Klimawandel: Welche Zukunft hat die Klimapolitik?

Die gegenwärtige im Kyoto-Protokoll festgelegte Klimapolitik versucht vorrangig, dem Klimawandel mit einer Strategie der Emissionsverminderung zu begegnen. Die dort festgelegten Reduktionsziele für den CO2-Ausstoß sind für viele Länder nicht mehr zu realisieren. Und einige Länder, die zu den größten Emittenten gehören, vor allem die USA, haben sich dem Kyoto-Protokoll nicht angeschlossen. Sollte die Klimapolitik in Zukunft weniger auf Emissionsvermeidung und eher auf eine Anpassung an die Erderwärmung zielen?

Effectiveness of the AS03-Adjuvanted Vaccine against Pandemic Influenza Virus A/(H1N1) 2009 – A Comparison of Two Methods; Germany, 2009/10

During the autumn wave of the pandemic influenza virus A/(H1N1) 2009 (pIV) the German population was offered an AS03-adjuvanted vaccine. The authors compared results of two methods calculating the effectiveness of the vaccine (VE). The test-negative case-control method used data from virologic surveillance including influenza-positive and negative patients. An innovative case-series methodology explored data from all nationally reported laboratory-confirmed influenza cases. The proportion of reported cases occurring in vaccinees during an assumed unprotected phase after vaccination was compared with that occurring in vaccinees during their assumed protected phase. The test-negative case-control method included 1,749 pIV cases and 2,087 influenza test-negative individuals of whom 6 (0.3%) and 36 (1.7%), respectively, were vaccinated. The case series method included data from 73,280 cases. VE in the two methods was 79% (95% confidence interval (CI) = 35–93%; P = 0.007) and 87% (95% CI = 78–92%; P<0.001) for individuals less than 14 years of age and 70% (95% CI = −45%–94%, P = 0.13) and 74% (95% CI = 64–82%; P<0.001) for individuals above the age of 14. Both methods yielded similar VE in both age groups; and VE for the younger age group seemed to be higher

Healthy living on a healthy planet - Summary

Unsere Lebensweise macht krank und zerstört die natürlichen Lebensgrundlagen. In der Vision „Gesund leben auf einer gesunden Erde“ werden menschliche Lebensbereiche – Ernähren, Bewegen, Wohnen – gesund und umweltverträglich gestaltet sowie planetare Risiken – Klimawandel, Biodiversitätsverlust, Verschmutzung – bewältigt. Gesundheitssysteme nutzen ihre transformativen Potenziale, Bildung und Wissenschaft befördern gesellschaftliche Veränderungen. Die Vision ist nur mit internationaler Kooperation realisierbar und erfordert eine globale Dringlichkeitsgovernance.Our lifestyle is making us ill and is destroying the natural life-support systems. In the vision of ‘healthy living on a healthy planet’, human spheres of life – what we eat, how we move, where we live – are designed to be both healthy and environmentally compatible, and planetary risks – climate change, biodiversity loss, pollution – have been overcome. Health systems harness their transformative potential; education and science promote societal change. The vision can only be realized with international cooperation and requires what the WBGU terms global urgency governance

Excision of HIV-1 Proviral DNA by Recombinant Cell Permeable Tre-Recombinase

Over the previous years, comprehensive studies on antiretroviral drugs resulted in the successful introduction of highly active antiretroviral therapy (HAART) into clinical practice for treatment of HIV/AIDS. However, there is still need for new therapeutic approaches, since HAART cannot eradicate HIV-1 from the infected organism and, unfortunately, can be associated with long-term toxicity and the development of drug resistance. In contrast, novel gene therapy strategies may have the potential to reverse the infection by eradicating HIV-1. For example, expression of long terminal repeat (LTR)-specific recombinase (Tre-recombinase) has been shown to result in chromosomal excision of proviral DNA and, in consequence, in the eradication of HIV-1 from infected cell cultures. However, the delivery of Tre-recombinase currently depends on the genetic manipulation of target cells, a process that is complicating such therapeutic approaches and, thus, might be undesirable in a clinical setting. In this report we demonstrate that E.coli expressed Tre-recombinases, tagged either with the protein transduction domain (PTD) from the HIV-1 Tat trans-activator or the translocation motif (TLM) of the Hepatitis B virus PreS2 protein, were able to translocate efficiently into cells and showed significant recombination activity on HIV-1 LTR sequences. Tre activity was observed using episomal and stable integrated reporter constructs in transfected HeLa cells. Furthermore, the TLM-tagged enzyme was able to excise the full-length proviral DNA from chromosomal integration sites of HIV-1-infected HeLa and CEM-SS cells. The presented data confirm Tre-recombinase activity on integrated HIV-1 and provide the basis for the non-genetic transient application of engineered recombinases, which may be a valuable component of future HIV eradication strategies

An intercomparison study of four different techniques for measuring the chemical composition of nanoparticles

Currently, the complete chemical characterization of nanoparticles (< 100 nm) represents an analytical challenge, since these particles are abundant in number but have negligible mass. Several methods for particle-phase characterization have been recently developed to better detect and infer more accurately the sources and fates of sub-100 nm particles, but a detailed comparison of different approaches is missing. Here we report on the chemical composition of secondary organic aerosol (SOA) nanoparticles from experimental studies of α-pinene ozonolysis at −50, −30, and −10 ∘C and intercompare the results measured by different techniques. The experiments were performed at the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). The chemical composition was measured simultaneously by four different techniques: (1) thermal desorption–differential mobility analyzer (TD–DMA) coupled to a NO$^-_3$ chemical ionization–atmospheric-pressure-interface–time-of-flight (CI–APi–TOF) mass spectrometer, (2) filter inlet for gases and aerosols (FIGAERO) coupled to an I$^−$ high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS), (3) extractive electrospray Na$^+$ ionization time-of-flight mass spectrometer (EESI-TOF), and (4) offline analysis of filters (FILTER) using ultra-high-performance liquid chromatography (UHPLC) and heated electrospray ionization (HESI) coupled to an Orbitrap high-resolution mass spectrometer (HRMS). Intercomparison was performed by contrasting the observed chemical composition as a function of oxidation state and carbon number, by estimating the volatility and comparing the fraction of volatility classes, and by comparing the thermal desorption behavior (for the thermal desorption techniques: TD–DMA and FIGAERO) and performing positive matrix factorization (PMF) analysis for the thermograms. We found that the methods generally agree on the most important compounds that are found in the nanoparticles. However, they do see different parts of the organic spectrum. We suggest potential explanations for these differences: thermal decomposition, aging, sampling artifacts, etc. We applied PMF analysis and found insights of thermal decomposition in the TD–DMA and the FIGAERO