Monitoring the Formation of Nickel-Poor and Nickel-Rich Oxide Cathode Materials for Lithium-Ion Batteries with Synchrotron Radiation.

The syntheses of Ni-poor (NCM111, LiNi1/3Co1/3Mn1/3O2) and Ni-rich (NCM811 LiNi0.8Co0.1Mn0.1O2) lithium transition-metal oxides (space group R3̅m) from hydroxide precursors (Ni1/3Co1/3Mn1/3(OH)2, Ni0.8Co0.1Mn0.1(OH)2) are investigated using in situ synchrotron powder diffraction and near-edge X-ray absorption fine structure spectroscopy. The development of the layered structure of these two cathode materials proceeds via two utterly different reaction mechanisms. While the synthesis of NCM811 involves a rock salt-type intermediate phase, NCM111 reveals a layered structure throughout the entire synthesis. Moreover, the necessity and the impact of a preannealing step and a high-temperature holding step are discussed.

Observation of Exchange Interaction in Iron(II) Spin Crossover Molecules in Contact with Passivated Ferromagnetic Surface of Co/Au(111).

Spin crossover (SCO) complexes sensitively react on changes of the environment by a change in the spin of the central metallic ion making them ideal candidates for molecular spintronics. In particular, the composite of SCO complexes and ferromagnetic (FM) surfaces would allow spin-state switching of the molecules in combination with the magnetic exchange interaction to the magnetic substrate. Unfortunately, when depositing SCO complexes on ferromagnetic surfaces, spin-state switching is blocked by the relatively strong interaction between the adsorbed molecules and the surface. Here, the Fe(II) SCO complex [FeII (Pyrz)2 ] (Pyrz = 3,5-dimethylpyrazolylborate) with sub-monolayer thickness in contact with a passivated FM film of Co on Au(111) is studied. In this case, the molecules preserve thermal spin crossover and at the same time the high-spin species show a sizable exchange interaction of > 0.9 T with the FM Co substrate. These observations provide a feasible design strategy in fabricating SCO-FM hybrid devices.

On the dates of publication of four European species of Scolopendra Linnaeus, 1758 described by C. L. Koch (Myriapoda, Chilopoda).

Current studies on European Scolopendra Linnaeus, 1758 revealed inconsistencies in the use of the date of publications containing original descriptions by C. L. Koch. These dates are reviewed in the present paper. As a result, the following commonly attributed dates of description have to be amended: S. clavipes C. L. Koch, 1847, S. italica C. L. Koch, 1837, S. graeca C. L. Koch, 1847, and S. germanica C. L. Koch, 1837. The work containing the original description of all these taxa was published in 1836 by C. L. Koch as Heft 9 of the rare series Deutschlands Crustaceen, Myriapoden und Arachniden. Two of these taxa were introduced by a short, inconspicuous paragraph and without illustration. The remaining two were wrongly dated short time after their descriptions, which were never questioned and have still being used until today.

Analyzing the Local Electronic Structure of Co3O4 Using 2p3d Resonant Inelastic X-ray Scattering.

We present the cobalt 2p3d resonant inelastic X-ray scattering (RIXS) spectra of Co3O4. Guided by multiplet simulation, the excited states at 0.5 and 1.3 eV can be identified as the 4 T 2 excited state of the tetrahedral Co2+ and the 3 T 2g excited state of the octahedral Co3+, respectively. The ground states of Co2+ and Co3+ sites are determined to be high-spin 4 A 2(T d ) and low-spin 1 A 1g (Oh ), respectively. It indicates that the high-spin Co2+ is the magnetically active site in Co3O4. Additionally, the ligand-to-metal charge transfer analysis shows strong orbital hybridization between the cobalt and oxygen ions at the Co3+ site, while the hybridization is weak at the Co2+ site.

Electron-momentum dependence of electron-phonon coupling underlies dramatic phonon renormalization in YNi2B2C.

Electron-phonon coupling, i.e., the scattering of lattice vibrations by electrons and vice versa, is ubiquitous in solids and can lead to emergent ground states such as superconductivity and charge-density wave order. A broad spectral phonon line shape is often interpreted as a marker of strong electron-phonon coupling associated with Fermi surface nesting, i.e., parallel sections of the Fermi surface connected by the phonon momentum. Alternatively broad phonons are known to arise from strong atomic lattice anharmonicity. Here, we show that strong phonon broadening can occur in the absence of both Fermi surface nesting and lattice anharmonicity, if electron-phonon coupling is strongly enhanced for specific values of electron-momentum, k. We use inelastic neutron scattering, soft x-ray angle-resolved photoemission spectroscopy measurements and ab-initio lattice dynamical and electronic band structure calculations to demonstrate this scenario in the highly anisotropic tetragonal electron-phonon superconductor YNi2B2C. This new scenario likely applies to a wide range of compounds.

Opportunities and challenges of applying advanced X-ray spectroscopy to actinide and lanthanide N-donor ligand systems.

N-donor ligands such as n-Pr-BTP [2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine] preferentially bind trivalent actinides (An3+) over trivalent lanthanides (Ln3+) in liquid-liquid separation. However, the chemical and physical processes responsible for this selectivity are not yet well understood. Here, an explorative comparative X-ray spectroscopy and computational (L3-edge) study for the An/Ln L3-edge and the N K-edge of [An/Ln(n-Pr-BTP)3](NO3)3, [Ln(n-Pr-BTP)3](CF3SO3)3 and [Ln(n-Pr-BTP)3](ClO4)3 complexes is presented. High-resolution X-ray absorption near-edge structure (HR-XANES) L3-edge data reveal additional features in the pre- and post-edge range of the spectra that are investigated using the quantum chemical codes FEFF and FDMNES. X-ray Raman spectroscopy studies demonstrate the applicability of this novel technique for investigations of liquid samples of partitioning systems at the N K-edge.

First-time synthesis of a magnetoelectric core-shell composite via conventional solid-state reaction.

In recent years, multiferroics and magnetoelectrics have demonstrated their potential for a variety of applications. However, no magnetoelectric material has been translated to a real application yet. Here, we report for the first time that a magnetoelectric core-shell ceramic, is synthesized via a conventional solid-state reaction, where core-shell grains form during a single sintering step. The core consists of ferrimagnetic CoFe2O4, which is surrounded by a ferroelectric shell consisting of (BiFeO3)x-(Bi1/2K1/2TiO3)1-x. We establish the core-shell nature of these grains by transmission-electron microscopy (TEM) and find an epitaxial crystallographic relation between core and shell, with a lattice mismatch of 6 ± 0.7%. The core-shell grains exhibit exceptional magnetoelectric coupling effects that we attribute to the epitaxial connection between the magnetic and ferroelectric phase, which also leads to magnetic exchange coupling as demonstrated by neutron diffraction. Apparently, ferrimagnetic CoFe2O4 cores undergo a non-centrosymmetric distortion of the crystal structure upon epitaxial strain from the shell, which leads to simultaneous ferrimagnetism and piezoelectricity. We conclude that in situ core-shell ceramics offer a number of advantages over other magnetoelectric composites, such as lower leakage current, higher density and absence of substrate clamping effects. At the same time, the material is predestined for application, since its preparation is cost-effective and only requires a single sintering step. This discovery adds a promising new perspective for the application of magnetoelectric materials.

Superior Magnetic Performance in FePt L10 Nanomaterials.

The discovery of the high maximum energy product of 59 MGOe for NdFeB magnets is a breakthrough in the development of permanent magnets with a tremendous impact in many fields of technology. This value is still the world record, for 40 years. This work reports on a reliable and robust route to realize nearly perfectly ordered L10 -phase FePt nanoparticles, leading to an unprecedented energy product of 80 MGOe at room temperature. Furthermore, with a 3 nm Au coverage, the magnetic polarization of these nanomagnets can be enhanced by 25% exceeding 1.8 T. This exceptional magnetization and anisotropy is confirmed by using multiple imaging and spectroscopic methods, which reveal highly consistent results. Due to the unprecedented huge energy product, this material can be envisaged as a new advanced basic magnetic component in modern micro and nanosized devices.

The Carabidae (Coleoptera) of Shada Al-A'Ala Nature Reserve, Southwestern Saudi Arabia, with description of a new species of Paussinae.

We report the Carabidae collected at the Shada Al-A'Ala Nature Reserve (SANR) in Baha Province in southwestern Saudi Arabia during 2013-2015. In total, 62 carabid species and subspecies representing 39 genera, 17 tribes, and 10 subfamilies were identified, including one new species, Paussusminutulus Nagel & Rasool, sp. n, four new country records, and 24 species that are new provincial records for Baha. The carabid fauna was dominated by the Lebiini with 19 species. A high number of species were rarely collected (34 species) in comparison to the more abundant and common species (9 species). The highest number of species (52 species) was collected during autumn. The carabids of SANR are represented by a large component of Afrotropical faunal elements (28.1%) and smaller numbers of Oriental species (3.5%) and endemic taxa (5.3%). In comparison to Garf Raydah Nature Reserve in Asir Province, also in southwestern Saudi Arabia, SANR had an equal number of carabids sharing 64.5% of the species but with lower number of endemic elements. Our study can serve as a component for implementing a conservation plan for SANR using carabid beetles as sentinel taxa. These research results may support future ecological studies on SNAR carabids.

Faunistic inventory and zoogeographical analysis of the ground beetles (Coleoptera, Carabidae) of Garf Raydah Nature Reserve, Southwestern of Saudi Arabia, and description of a new species of Paussinae.

Study of ground beetles of the Garf Raydah Nature Reserve, located in the Asir Mountains of southwestern Kingdom of Saudi Arabia (KSA) resulted in one species, Paussus abditus Nagel, sp. n. described as new to science. Thirteen species (21.3%) are reported as new country records and fifteen species (24.6%) are new records for Asir Province. Adult beetles were collected from 2013 to 2017. The determination of this material yielded a total of 61 species in 40 genera and 17 tribes belonging to nine subfamilies of Carabidae. The species richness represented approximately 36.1% of carabid species previously reported from KSA. The most species rich tribes were the Lebiini (20 species), the Harpalini (10 species), and the Bembidiini (6 species). The life form analysis of adults indicated 18 life form types that are grouped into three categories, Zoophagous (77.1%), Mixophytophagous (18.0%), and Myrmecophilous (4.9%). Zoogeographical analyses indicated that the Afrotropical (19.3%) and the Saharo-Arabian (19.3%) species dominate the carabid fauna of this region of KSA. Coryza cf. maculata (Nietner, 1856) is considered the only Oriental representative. Only one cosmopolitan species, Perigona nigriceps (Dejean, 1831), was collected. Eleven endemics were identified; six species are considered KSA endemics and five are Arabian Peninsula endemics.

Vanishing refuge? Testing the forest refuge hypothesis in coastal East Africa using genome-wide sequence data for seven amphibians.

High-throughput sequencing data have greatly improved our ability to understand the processes that contribute to current biodiversity patterns. The "vanishing refuge" diversification model is speculated for the coastal forests of eastern Africa, whereby some taxa have persisted and diversified between forest refugia, while others have switched to becoming generalists also present in non-forest habitats. Complex arrangements of geographical barriers (hydrology and topography) and ecological gradients between forest and non-forest habitats may have further influenced the region's biodiversity, but elucidation of general diversification processes has been limited by lack of suitable data. Here, we explicitly test alternative diversification modes in the coastal forests using genome-wide single nucleotide polymorphisms, mtDNA, spatial and environmental data for three forest (Arthroleptis xenodactyloides, Leptopelis flavomaculatus and Afrixalus sylvaticus) and four generalist (Afrixalus fornasini, A. delicatus, Leptopelis concolor and Leptopelis argenteus) amphibians. Multiple analyses provide insight about divergence times, spatial population structure, dispersal barriers, environmental stability and demographic history. We reveal highly congruent intra-specific diversity and population structure across taxa, with most divergences occurring during the late Pliocene and Pleistocene. Although stability models support the existence of some forest refugia, dispersal barriers and demographic models point towards idiosyncratic diversification modes across taxa. We identify a consistent role for riverine barriers in the diversification of generalist taxa, but mechanisms of diversification are more complex for forest taxa and potentially include topographical barriers, forest refugia and ecological gradients. Our work demonstrates the complexity of diversification processes in this region, which vary between forest and generalist taxa, but also for ecologically similar species with shared population boundaries.

Impact of species delimitation and sampling on niche models and phylogeographical inference: A case study of the East African reed frog Hyperolius substriatus Ahl, 1931.

Ecological niche models (ENMs) have been used in a wide range of ecological and evolutionary studies. In biogeographic studies these models have, among other things, helped in the discovery of new allopatric populations, and even new species. However, small sample sizes and questionable taxonomic delimitation can challenge models, often decreasing their accuracy. Herein we examine the sensitivity of ENMs to the addition of new, geographically isolated populations, and the impact of applying different taxonomic delimitations. The East African reed frog Hyperolius substriatus Ahl, 1931 was selected as a case study because it has been the subject of previous ENM predictions. Our results suggest that addition of new data and reanalysis of species lineages of H. substriatus improved our understanding of the evolutionary history of this group of frogs. ENMs provided robust predictions, even when some populations were deliberately excluded from the models. Splitting the lineages based on genetic relationships and analysing the ENMs separately provided insights about the biogeographical processes that led to the current distribution of H. substriatus.

Complex within a Complex: Integrative Taxonomy Reveals Hidden Diversity in Cicadetta brevipennis (Hemiptera: Cicadidae) and Unexpected Relationships with a Song Divergent Relative.

Multiple sources of data in combination are essential for species delimitation and classification of difficult taxonomic groups. Here we investigate a cicada taxon with unusual cryptic diversity and we attempt to resolve seemingly contradictory data sets. Cicada songs act as species-specific premating barriers and have been used extensively to reveal hidden taxonomic diversity in morphologically similar species. The Palaearctic Cicadetta montana species complex is an excellent example where distinct song patterns have disclosed multiple recently described species. Indeed, two taxa turned out to be especially diverse in that they form a "complex within the complex": the Cicadetta cerdaniensis song group (four species studied previously) and Cicadetta brevipennis (examined in details here). Based on acoustic, morphological, molecular, ecological and spatial data sampled throughout their broad European distribution, we find that Cicadetta brevipennis s. l. comprises five lineages. The most distinct lineage is identified as Cicadetta petryi Schumacher, 1924, which we re-assign to the species level. Cicadetta brevipennis litoralis Puissant & Hertach ssp. n. and Cicadetta brevipennis hippolaidica Hertach ssp. n. are new to science. The latter hybridizes with Cicadetta brevipennis brevipennis Fieber, 1876 at a zone inferred from intermediate song patterns. The fifth lineage requires additional investigation. The C. cerdaniensis and the C. brevipennis song groups exhibit characteristic, clearly distinct basic song patterns that act as reproductive barriers. However, they remain completely intermixed in the Bayesian and maximum likelihood COI and COII mitochondrial DNA phylogenies. The closest relative of each of the four cerdaniensis group species is a brevipennis group taxon. In our favoured scenario the phylogenetic pairs originated in common Pleistocene glacial refuges where the taxa speciated and experienced sporadic inter-group hybridization leading to extensive introgression and mitochondrial capture.

No ecological opportunity signal on a continental scale? Diversification and life-history evolution of African true toads (Anura: Bufonidae).

The niche-filling process predicted by the "ecological opportunity" (EO) model is an often-invoked mechanism for generating exceptional diversity in island colonizers. Whether the same process governs lineage accumulation and trait disparity during continental colonization events is less clear. Here, we test this prediction by investigating the rate dynamics and trait evolution of one of Africa's most widespread amphibian colonizers, the true toads (Bufonidae). By reconstructing the most complete molecular phylogeny of African Bufonidae to date, we find that the diversification of lineages in Africa best conforms to a constant rate model throughout time and across subclades, with little support for EO. Evolutionary rates of life-history traits have similarly been constant over time. However, an analysis of generalists and specialists showed a shift toward higher speciation rates associated with habitat specialization. The overall lack of EO signal can be interpreted in a number of ways and we propose several explanations. Firstly, methodological issues might preclude the detection of EO. Secondly, colonizers might not experience true EO conditions and due to the size, ecological heterogeneity and age of landmasses, the diversification processes might be more complex. Thirdly, lower speciation rates of habitat generalists may have affected overall proliferation of lineages.

Unraveling the Degradation Process of LiNi0.8Co0.15Al0.05O2 Electrodes in Commercial Lithium Ion Batteries by Electronic Structure Investigations.

The degradation of LiNi0.8Co0.15Al0.05O2 (LNCAO) is reflected by the electrochemical performance in the fatigued state and correlated with the redox behavior of these cathodes. The detailed electrochemical performance of these samples is investigated by galvanostatic and voltammetric cycling as well as with the galvanostatic intermittent titration technique (GITT). Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to investigate the oxidation state of all three materials at the Ni L2,3, O K, and Co L2,3 edges at five different states of charge. Surface and more bulklike properties are distinguished by total electron yield (TEY) and fluorescence yield (FY) measurements. The electrochemical investigations revealed that the changes in the cell performance of the differently aged materials can be explained by considering the reaction kinetics of the intercalation/deintercalation process. The failure of the redox process of oxygen and nickel at low voltages leads to a significant decrease of the reaction rates in the fatigued cathodes. The accompanied cyclic voltammogram (CV) peaks appear as two peaks because of the local minimum of the reaction rate, although it is one peak in the CV of the calendarically aged LNCAO. The absence of the oxidation/reduction process at low voltages can be traced back to changes in the surface morphology (formation of a NiO-like structure). Further consequences of these material changes are overpotentials, which lead to capacity losses of up to 30% (cycled with a C/3 rate).

Electronic structure at transition metal phthalocyanine-transition metal oxide interfaces: Cobalt phthalocyanine on epitaxial MnO films.

The electronic structure of the interface between cobalt phthalocyanine (CoPc) and epitaxially grown manganese oxide (MnO) thin films is studied by means of photoemission (PES) and X-ray absorption spectroscopy (XAS). Our results reveal a flat-lying adsorption geometry of the molecules on the oxide surface which allows a maximal interaction between the π-system and the substrate. A charge transfer from MnO, in particular, to the central metal atom of CoPc is observed by both PES and XAS. The change of the shape of N-K XAS spectra at the interface points, however, to the involvement of the Pc macrocycle in the charge transfer process. As a consequence of the charge transfer, energetic shifts of MnO related core levels were observed, which are discussed in terms of a Fermi level shift in the semiconducting MnO films due to interface charge redistribution.

Copper sulphate reduces the metabolic activity of Gammarus fossarum in laboratory and field experiments.

The specialised fauna of freshwater springs is affected by contamination of the water with xenobiotics from human activities in the surrounding landscape. We assessed the effects of exposure to toxins in laboratory and field experiments by using copper sulphate as a model substance and Gammarus fossarum Koch, 1836, as the model organism. This amphipod is a common representative of the European spring fauna and copper is a widespread contaminant, mainly from agricultural practice. The experiments were conducted in test chambers placed in flow channels and directly in a spring. The gammarids were fed with conditioned beech leaf discs, which had been exposed to a 0.8 mg Cu/L solution for 96 h. The feeding activity of the amphipods was quantified on the level of the organism; and the respiratory electron transport system (ETS) assay was conducted in order to determine changes on the cellular level in the test organisms. The results show that the feeding activity, when the leaf discs were contaminated with copper, was not significantly different from the control. The ETS activity of the gammarids, which had been feeding on the copper contaminated leaf discs was however significantly reduced. The results followed the same pattern for gammarids from both the laboratory and the spring. By conducting the experiments not only in a laboratory but also directly in a spring in the field, we took a crucial step towards a more realistic approach when examining environmental pollutants on an organism. Our findings demonstrate the importance of conducting experiments out in the field, in natural conditions, as well as in the laboratory.

Effects of increased temperatures on Gammarus fossarum under the influence of copper sulphate.

The specialised fauna of freshwater springs will have to cope with a possible temperature rise owing to Global Change. It is affected additionally by contamination of the water with xenobiotics from human activities in the surrounding landscape. We assessed the combined effects of temperature increase and exposure to toxins in laboratory experiments by using copper sulphate as a model substance and Gammarus fossarum Koch, 1835, as the model organism. This amphipod is a common representative of the European spring fauna and copper ions are widespread contaminants, mainly from agricultural practice. The experiments were conducted in boxes placed in flow channels and the water temperatures were varied. The gammarids were fed with conditioned beech leaf discs. The feeding activity of the amphipods was quantified on the level of the organism; and the respiratory electron transport system (ETS) assay was conducted in order to determine changes on the cellular level in the test organisms. The results show that the feeding activity increased slightly with higher water temperature. The sub-lethal copper dose had no significant effect other than a trend towards lower feeding activity. The ETS activity was significantly higher at the higher water temperatures, and the copper ions significantly lowered the ETS activity of the organisms. The combination of the two methods was useful when testing for combined effects of environmental changes and pollutants on a species. From the results one can reasonably infer a higher risk of adverse effects with increase in water temperature and exposure to a particular heavy metal.

Photodegradation of C-PCPDTBT and Si-PCPDTBT: influence of the bridging atom on the stability of a low-band-gap polymer for solar cell application.

The kinetics of photodegradation and the reactivity of different sites of the low-band-gap polymers poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (C-PCPDTBT) and poly[2,6-(4,4-bis-(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-alt-4,7-(2,1,3-benzothiadiazole)] (Si-PCPDTBT) are investigated as thin films and are compared to those of poly(3-hexylthiophene) (P3HT). The decay kinetics are monitored with UV/Vis spectroscopy and the reactivity and product evolution are investigated with X-ray photoelectron spectroscopy (XPS). Both polymers exhibit higher stability than P3HT. The bridging atom in the cyclopentadithiophene (CPDT) subunit has a significant influence on the stability. Varying oxidation rates for the different elements were observed. In the case of Si-PCPDTBT, the silicon atom is oxidized primarily, whereas the photooxidation rates of the other elements are reduced relative to C-PCPDTBT. Additionally, XPS experiments with varying excitation energies reveal a significant reaction gradient within a few nanometers of the surface of degraded thin films of C-PCPDTBT.

Luminescence, patterned metallic regions, and photon-mediated electronic changes in single-sided fluorinated graphene sheets.

Single-sided fluorination has been predicted to open an electronic band gap in graphene and to exhibit unique electronic and magnetic properties; however, this has not been substantiated by experimental reports. Our comprehensive experimental and theoretical study of this material on a SiC(0001) substrate shows that single-sided fluorographene exhibits two phases, a stable one with a band gap of ∼6 eV and a metastable one, induced by UV irradiation, with a band gap of ∼2.5 eV. The metastable structure, which reverts to the stable "ground-state" phase upon annealing under emission of blue light, in our view is induced by defect states, based on the observation of a nondispersive electronic state at the top of the valence band, not unlike that found in organic molecular layers. Our structural data show that the stable C2F ground state has a "boat" structure, in agreement with our X-ray magnetic circular dichroism data, which show the absence of an ordered magnetic phase. A high flux of UV or X-ray photons removes the fluorine atoms, demonstrating the possibility of lithographically patterning conducting regions into an otherwise semiconducting 2D material.