Alien eating alien - rapid spread of Aceria fraxiniflora, a non-native gall mite of the invasive green ash (Fraxinus pennsylvanica) in Central-Eastern Europe

The North American gall mite Aceria fraxiniflora was first recorded in Europe in southeast Hungary in 2017. Since then, it has shown a remarkably rapid spread on its host, the also North American green ash (Fraxinus pennsylvanica). By the beginning of 2023 it has been recorded in eight Central-Eastern European countries. In 2022 it was recorded on the other North American ash (Fraxinus Americana) in Zagreb (Croatia) and in Szarvas Arboretum (SE Hungary). Possible reasons and outcomes of this spread are discussed.

A monochromatic confocal micro-x-ray fluorescence (μXRF) spectrometer for the lab

Confocal micro-x-ray fluorescence (μXRF) is a powerful tool to analyze the spatial distribution of major, minor, and trace elements in three dimensions. Typical (confocal) μXRF measurements in the lab use polychromatic excitation, complicating quantification and fundamental parameter-based corrections and furthermore deteriorating peak-to-background ratios due to scattered bremsstrahlung. The goal for the new setup was to remedy these problems, without sacrificing spatial resolution, and keep it flexible for different excitation energies and transportation to other sources. The source assembly consists of a water-cooled fine-focus x-ray diffraction tube and a parallel beam-mirror, which produces a quasi-parallel, monochromatic beam. The presented results were obtained using a 2 kW molybdenum tube and a mirror for Mo-Kα. The confocal setup itself consists of two polycapillary half-lenses, one for the source side and the other for the detector side, where a 50 mm² silicon drift detector is mounted. Both polycapillaries have a focus size of ∼15 μm for Mo-Kα. The second polycapillary can also be exchanged for a custom-designed collimator in order to perform non-confocal μXRF. Details of the technical setup and results from technical and biological samples are presented. Detection limits for selected elements from Ca to Pb in the confocal and non-confocal mode were established (e.g., 1 μg/g non-confocal and 20 μg/g confocal for As) using the NIST standard reference materials (SRMs) 621 and 1412. Furthermore, the results of the measurements of SRM 621 were evaluated using the fundamental parameter based quantification software ATI-QUANT. The results are compared with the certified values and generally are in good agreement.

Thermopower enhancement by encapsulating cerium in clathrate cages

The increasing worldwide energy consumption calls for the design of more efficient energy systems. Thermoelectrics could be used to convert waste heat back to useful electric energy if only more efficient materials were available. The ideal thermoelectric material combines high electrical conductivity and thermopower with low thermal conductivity. In this regard, the intermetallic type-I clathrates show promise with their exceedingly low lattice thermal conductivities. Here we report the successful incorporation of cerium as a guest atom into the clathrate crystal structure. In many simpler intermetallic compounds, this rare earth element is known to lead, through the Kondo interaction, to strong correlation phenomena including the occurrence of giant thermopowers at low temperatures. Indeed, we observe a 50% enhancement of the thermopower compared with a rare-earth-free reference material. Importantly, this enhancement occurs at high temperatures and we suggest that a rattling-enhanced Kondo interaction underlies this effect.

Magnetic soft modes in the distorted triangular antiferromagnet α-CaCr2O4

In this Letter, we explore the phase diagram and excitations of a distorted triangular lattice antiferromagnet. The unique two-dimensional distortion considered here is very different from the "isosceles"-type distortion that has been extensively investigated. We show that it is able to stabilize a 120° spin structure for a large range of exchange interaction values, while new structures are found for extreme distortions. A physical realization of this model is α-CaCr(2)O(4), which has a 120° structure but lies very close to the phase boundary. This is verified by inelastic neutron scattering which reveals unusual rotonlike minima at reciprocal space points different from those corresponding to the magnetic order.

Electron-phonon coupling in the conventional superconductor YNi2B2C at high phonon energies studied by time-of-flight neutron spectroscopy

We report an inelastic neutron scattering investigation of phonons with energies up to 159 meV in the conventional superconductor YNi(2)B(2)C. Using the sweep mode, a newly developed time-of-flight technique involving the continuous rotation of a single crystal specimen, allowed us to measure a four-dimensional volume in (Q, E) space and, thus, determine the dispersion surface and linewidths of the A(1g) (≈102 meV) and A(u) (≈159 meV) type phonon modes over the whole Brillouin zone. Despite of having linewidths of Γ=10 meV, A(1g) modes do not strongly contribute to the total electron-phonon coupling constant λ. However, experimental linewidths show a remarkable agreement with ab initio calculations over the complete phonon energy range, demonstrating the accuracy of such calculations in a rare comparison to a comprehensive experimental data set.

Phonon-lifetimes in demixing systems

The dynamics of silver-alkali halide mixed single crystals (Ag(x)Na(1-x)Br, x = 0.23, 0.35, 0.40 and 0.70) were studied by inelastic neutron scattering during the process of spinodal decomposition. Using the thermal three-axes spectrometer PUMA as well as the time-of-flight spectrometer IN5, the time evolution of phonons was observed in time-resolved, stroboscopic measurements. Complementary to the study of long wavelength acoustic phonons, as studied previously, we extended these investigations to Brillouin-zone boundary modes that are particularly sensitive to variations of the local structure. Starting from the homogeneous mixed phase the behaviour of these modes during demixing is observed in real-time. A simple dynamical model based on local structure variants helps to interpret the results. It is shown that the phonon lifetimes vary strongly during the phase separation and increase drastically during the coarsening process. Up to a critical size of precipitates of about 10 nm, zone-boundary modes are found to be strongly damped, while beyond the line widths are reduced to the experimental resolution. This finding leads to the conclusion that the typical mean free path of these modes is of the order of 10 nm, which corresponds to 20 unit cells.

Highly anisotropic anomaly in the dispersion of the copper-oxygen bond-bending phonon in superconducting YBa2Cu3O7 from inelastic neutron scattering

Motivated by predictions of a substantial contribution of the "buckling" vibration of the CuO(2) layers to d-wave superconductivity in the cuprates, we have performed an inelastic neutron scattering study of this phonon in an array of untwinned crystals of YBa(2)Cu(3)O(7). The data reveal a pronounced softening of the phonon at the in-plane wave vector q=(0,0.3) upon cooling below ~105 K, but no corresponding anomaly at q=(0.3,0). Based on the observed in-plane anisotropy, we argue that the electron-phonon interaction responsible for this anomaly supports an electronic instability associated with a uniaxial charge-density modulation and does not mediate d-wave superconductivity.

Switching behaviour of modulated ferroelectrics: the kinetics of the field induced lock-in transition in K₂SeO₄

The field induced switching process across the ferroelectric lock-in transition in K(2)SeO(4) has been studied on a millisecond timescale using stroboscopic neutron diffraction. The time evolution of both the first and the third order satellites was examined. The time constants are found to vary with temperature between 0.2 and 1.2 ms. This is an order of magnitude faster than in the isostructural Rb(2)ZnCl(4). Moreover, the time dependence of the satellite's linewidth provides information about the evolution of the coherence of the modulated structure.

Incommensurate magnetic order and dynamics induced by spinless impurities in YBa(2)Cu(3)O(6.6)

We report an inelastic-neutron-scattering and muon-spin-relaxation study of the effect of 2% spinless (Zn) impurities on the magnetic order and dynamics of YBa(2)Cu(3)O(6.6), an underdoped high-temperature superconductor that exhibits a prominent spin pseudogap in its normal state. Zn substitution induces static magnetic order at low temperatures and triggers a large-scale spectral-weight redistribution from the magnetic resonant mode at 38 meV into uniaxial, incommensurate spin excitations with energies well below the spin pseudogap. These observations indicate a competition between incommensurate magnetic order and superconductivity close to a quantum critical point. Comparison to prior data on La(2-x)Sr(x)CuO(4) suggests that this behavior is universal for the layered copper oxides and analogous to impurity-induced magnetic order in one-dimensional quantum magnets.

Quantitative determination of domain distribution in SrTiO3-competing effects of applied electric field and mechanical stress

Below its ordering temperature at 105 K, perovskite-type SrTiO(3) exhibits a tetragonal phase with three different structural domains that are strongly influenced by the application of uniaxial mechanical stresses and electric fields. A careful neutron diffraction study of superlattice reflections provides full quantitative information about the varying domain distributions under external loads as a function of temperature. It is shown that electric field and uniaxial stress exhibit competitive effects and the simultaneous application leads to a complex redistribution behaviour of the tetragonal domains. The results are discussed in the context of the formation of a field induced ferroelectric phase at low temperatures. The experimental findings demonstrate that its polarization is always perpendicular to the tetragonal axis and the polar phase has orthorhombic symmetry.

Direct observation of the superconducting gap in phonon spectra

We show that the superconducting energy gap 2Delta can be directly observed in phonon spectra, as predicted by recent theories. In addition, since each phonon probes the gap on only a small part of the Fermi surface, the gap anisotropy can be studied in detail. Our neutron scattering investigation of the anisotropic conventional superconductor YNi2B2C demonstrates this new application of phonon spectroscopy.

Magnetic excitations in multiferroic TbMnO3: evidence for a hybridized soft mode

The magnetic excitations in multiferroic TbMnO3 have been studied by inelastic neutron scattering in the spiral and sinusoidally ordered phases. At the incommensurate magnetic zone center of the spiral phase, we find three low-lying magnons whose character has been fully determined using neutron-polarization analysis. The excitation at the lowest energy is the sliding mode of the spiral, and two modes at 1.1 and 2.5 meV correspond to rotations of the spiral rotation plane. These latter modes are expected to couple to the electric polarization. The 2.5 meV mode is in perfect agreement with recent infrared-spectroscopy data giving strong support to its interpretation as a hybridized phonon-magnon excitation.

Investigation of nanocrystalline CdS–glutathione particles by radial distribution function

Using high-energy synchrotron radiation, powder diffraction experiments were carried out on CdS nanocrystals stabilized with glutathione. The radial distribution function was calculated from the data and analysed. The nanoparticle core, of diameter estimated as 15–20 Å, consists of Cd and S atoms in the proportion 1:1. Inside the core, both Cd and S atoms coordinate each other approximately tetrahedrally. The surface S atoms are connected to just two or three Cd atoms of the core and belong to the glutathione molecules of the particle shell. These S atoms are also a part of the core structure and contribute about one half of the total number of S atoms per particle. First-neighbour Cd—S distances are 2.523 Å with a narrow distance distribution. No difference is observed between the lengths of Cd—S bonds involving the sulfur of the glutathione molecules and the sulfur atoms which are solely bound to Cd. The bond angle Cd—S—Cd at the surface bridging S atoms of glutathione isca99.5°,i.e.significantly smaller than an average one of 109.5° characteristic of the Cd and S atom packing inside the core. Beyond the range of the near interatomic distances, the influence of the surface and the defects cause a significant distinction of the particle core structure from those of zincblende and wurtzite, characteristic of bulk CdS.

Predictive value of decreased p27Kip1 protein expression for the recurrence-free and long-term survival of prostate cancer patients

The p27Kip1 gene has been identified as inductor of cell cycle arrest at the G1 checkpoint to prevent entry of somatic cells into the S phase of the cell cycle when substantial DNA damage has occurred. It has been suggested that decreased expression of the p27Kip1 protein may contribute to the development of human malignancies due to loss of critical antiproliferative mechanisms. In the present study, 95 specimens (T1-T4) from 95 randomly selected patients undergoing radical prostatectomy at the Urological Department of Hannover University (82 patients) as well as in the Josef Hospital Regensburg (13 patients) between 1981 and 1992 for whom tissue blocks for immunohistochemical investigation were available, were investigated for different biological and clinical characteristics as possible predictors for recurrence-free and long-term survival: age, depth of tumour infiltration, histological grade, lymph node status, as well as decreased expression of the p27Kip1 protein. After a median follow-up up of 56 months (24-151 months), seven of 21 (33%) patients (Group 1) with loss of p27Kip1 protein expression or a relative amount of <10% of positively stained tumour cells developed recurrent disease in contrast to 17 of 74 (23%) patients (Group 2) with retained p27Kip1 protein expression (> or =10% of positively stained tumour cells). The median recurrence-free survival was 14 months (5-40 months) for patients from Group 1 and 31 months (7-133 months) for Group 2 patients (P = 0.02). In multivariate analysis, loss of p27Kip1 protein expression was identified as the only independent prognostic parameter for recurrence-free survival. In contrast, neither the univariate nor the multivariate analysis showed a correlation between loss of p27Kip1 protein expression and the long-term survival of the patients. Prospective studies are urgently needed to confirm the independent prognostic value of decreased p27Kip1 protein expression together with overexpression of the p53 tumour suppressor protein in patients with localized prostate cancer. The availability of more refined prognostically important biological variables in addition to established prognostic factors like tumour stage or Gleason score might help decision making in patients at high risk for the development of local recurrence or systemic tumour progression.

Prognostic value of p27Kip1 and p21WAF/Cip protein expression in muscle invasive bladder cancer

Two genes, namely p27Kip1 and p21WAF/Cip1 that reveal distinct structural homology, have been identified as inductors of cell cycle arrest at the G1-checkpoint to prevent entry of somatic cells into the S phase of the cell cycle when substantial DNA damage has occurred. It was demonstrated that the p21WAF/Cip1 gene is induced by pathways dependent and independent from a functionally intact p53 tumour suppressor protein. It has been suggested that decreased expression both of the p21WAF/Cip1 and p27Kip1 protein may contribute to the development of human malignancies due to loss of critical antiproliferative mechanisms. So far, the role of altered p21WAF/Cip1 and mainly of a decreased p27Kip1 protein expression in patients with muscle invasive bladder cancer has not been investigated. In the present study, 50 tumour specimens from 50 patients undergoing radical cystectomy (T2-T4) were investigated for different biological and clinical characteristics as possible prognostic factors: age, depth of tumour infiltration (T-stage), histological grading (G), lymph node status as well as immunohistochemical staining for the p21WAF/Cip1 and p27Kip1 proteins. The median recurrence-free survival for patients with and without retained p21WAF/Cip1 protein expression was 54 months (3-86 months) and 13 months (1-40 months), respectively (p=0.07). During univariate analysis, loss of p21WAF/Cip1 protein expression (p=0.02), T-stage (p=0.02) and histological grading (p=0.03) were significant prognostic factors for survival, among which a negative reaction for the p21WAF/Cip1 protein (p=0.02) as well as T-stage (p=0.005) remained independent significant predictors during multivariate analysis. Loss of p27Kip1 protein expression was not correlated with the recurrence-free or the overall survival of the patients. Prospective studies are needed to confirm the independent prognostic potential of cell-cycle associated proteins such as p21WAF/Cip1 in patients with muscle invasive bladder cancer. The availability of more refined prognostic factors should assist decision making regarding the value of more aggressive treatment options, such as adjuvant or neoadjuvant chemotherapy, for defined subgroups of patients.