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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

There exists increasing evidence that the phase diagram of the high-transition temperature (Tc) cuprate superconductors is controlled by a quantum critical point. According to one distinct theoretical proposal, on decreasing the hole-carrier concentration a transition occurs to an ordered state with two circulating orbital currents per CuO2 square. Below the 'pseudogap' temperature T*(T*>Tc), the theory predicts a discrete order parameter and two weakly-dispersive magnetic excitations in structurally simple compounds which should be measurable by neutron scattering. Indeed, novel magnetic order and one such excitation were recently observed. Here, we demonstrate for tetragonal HgBa2CuO4+? the existence of a second excitation with local character, consistent with the theory. The excitations mix with conventional antiferromagnetic fluctuations, which points towards a unifying picture of magnetism in the cuprates that will probably require a multi-band description. [ABSTRACT FROM AUTHOR]

Magnetic Cooper-pairing mechanisms have been proposed for heavy-fermion and cuprate superconductors; however, strong electron correlations and complications arising from a pseudogap or competing phases have precluded commonly accepted theories. In the iron arsenides, the proximity of superconductivity and antiferromagnetism in the phase diagram, the apparently weak electron–phonon coupling and the ‘resonance peak’ in the superconducting spin-excitation spectrum have also fostered the hypothesis of magnetically mediated Cooper pairing. However, as most theories of superconductivity are based on a pairing boson of sufficient spectral weight in the normal state, detailed knowledge of the spin-excitation spectrum above the superconducting transition temperature Tc is required to assess the viability of this hypothesis. Using inelastic neutron scattering we have studied the spin excitations in optimally doped BaFe1.85Co0.15As2 (Tc=25 K) over a wide range of temperatures and energies. We present the results in absolute units and find that the normal-state spectrum carries a weight comparable to that in underdoped cuprates. In contrast to cuprates, however, the spectrum agrees well with predictions of the theory of nearly antiferromagnetic metals, without the aforementioned complications. We also show that the temperature evolution of the resonance energy monotonically follows the closing of the superconducting energy gap Δ, as expected from conventional Fermi-liquid approaches. Our observations point to a surprisingly simple theoretical description of the spin dynamics in the iron arsenides and provide a solid foundation for models of magnetically mediated superconductivity. [ABSTRACT FROM AUTHOR]

Phonons in a metal interact with conduction electrons which give rise to a finite linewidth. In the normal state, this leads to a Lorentzian shape of the phonon line. Density functional theory is able to predict the phonon linewidths as a function of wave vector for each branch of the phonon dispersion. An experimental verification of such predictions is feasible only for compounds with very strong electron{phonon coupling. YN2B2C was chosen as a test example because it is a conventional superconductor with a fairly high Tc (15.2 K). Inelastic neutron scattering experiments did largely confirm the theoretical predictions. Moreover, they revealed a strong temperature dependence of the linewidths of some phonons with particularly strong electron{phonon coupling which can as yet only qualitatively be accounted for by theory. For such phonons, marked changes of the phonon frequencies and linewidths were observed from room temperature down to 15 K. Further changes were observed on entering into the superconducting state. These changes can, however, not be described simply by a change of the phonon linewidth. [ABSTRACT FROM AUTHOR]

Discusses the results of powder diffraction experiments on CdS nanocrystals stabilized with glutathione. Use of high-energy synchrotron radiation; Calculation of the radial distribution function from the data; Evidence that the influence of the surface and the defects cause a significant distinction of the particle core structure from those of zincblende and wirtizite characteristic of bulk CdS.

Diffuse layers which are observed in different decagonal quasicrystals perpendicular to the unique 'periodic' axis are explained by one-dimensional (1D) columns of icosahedral Al clusters along this axis. From results of X-ray and purely elastic neutron diffraction experiments we give a qualitative explanation by basically off-layer atomic displacements which are grossly uncorrelated in different columnar clusters. A reversible temperature behaviour of the 1D superstructure which vanishes at high temperatures can be understood in the framework of this interpretation. Diffuse intensity modulations within the diffuse layers are discussed in terms of atomic displacements and chemical ordering within the icosahedral clusters which are the basic structural units of the columns. Computer simulations of different columnar models are carried out, their Fourier transforms are compared with the observed patterns. [ABSTRACT FROM AUTHOR]

Single-crystal X-ray diffraction was carried out on a decagonal Ni-rich phase in the Al-Co-Ni system with a nominal composition of Al72.5Co11Ni16.5. Apart from sharp Bragg reflections, satellite scattering was observed in Al72.5Co11Ni16.5 which is different from the satellite scattering observed in a Ni-poor phase with nominal composition Al72.5Co16.5Ni11. The two types of superorder scattering are interpreted in an unified way by periodic order superimposed on the quasiperiodic averaged substructure. This periodic regimes have a limited correlation length (short-range ordering). While the modulation period stays almost constant over a wide range of compositions in these decagonal alloys, the modulation vector is rotated by pi/10 if passing from Ni-rich (S satellites) to Ni-poor (C satellites) compositions. Arguments are given in favour of this interpretation which is also supported by computer simulations. [ABSTRACT FROM AUTHOR]

The p27[SUPKip1]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 p27[SUPKip1] 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 p27[SUPKip1] protein. After a median follow-up up of 56 months (24-151 months), seven of 21 (33%) patients (Group 1) with loss of p27[SUPKip1] 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 p27[SUPKip1] protein expression (≥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 p27[SUPKip1] 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 p27[SUPKip1] protein expression and the long-term survival of the patients. Prospective studies are urgently needed to confirm the independent prognostic value of decreased p27[SUPKip1] protein expression... [ABSTRACT FROM AUTHOR]

The elucidation of the pseudogap phenomenon of the high-transition-temperature (high-Tc) copper oxides-a set of anomalous physical properties below the characteristic temperature T* and above Tc-has been a major challenge in condensed matter physics for the past two decades. Following initial indications of broken time-reversal symmetry in photoemission experiments, recent polarized neutron diffraction work demonstrated the universal existence of an unusual magnetic order below T* (refs 3, 4). These findings have the profound implication that the pseudogap regime constitutes a genuine new phase of matter rather than a mere crossover phenomenon. They are furthermore consistent with a particular type of order involving circulating orbital currents, and with the notion that the phase diagram is controlled by a quantum critical point. Here we report inelastic neutron scattering results for HgBa2CuO4+δ that reveal a fundamental collective magnetic mode associated with the unusual order, and which further support this picture. The mode's intensity rises below the same temperature T* and its dispersion is weak, as expected for an Ising-like order parameter. Its energy of 52-56 meV renders it a new candidate for the hitherto unexplained ubiquitous electron-boson coupling features observed in spectroscopic studies. [ABSTRACT FROM AUTHOR]

Investigates the deposition of epitaxial YBa[sub 2]Cu[sub 3]O[sub x] thin films on sapphire using Y-stabilized zirconium dioxide buffer layer. Use of magnetron sputtering; Application of Rutherford backscattering spectrometry; Importance of sapphires in passive microwave devices.

Disordered decagonal Al[sub 72]Co[sub 16]Ni[sub 12] quasicrystals were investigated by recording diffuse neutron scattering at instruments D10 and IN8/ILL up to 1000 °C. This neutron work supplements X-ray-diffraction investigations, which do not provide a scattering contrast of the transition metals. Moreover, diffuse scattering of inelastic origin could be suppressed, within the resolution limits, by using an analyser. The temperature dependence of the diffuse scattering in the quasiperiodic plane indicates complex re-ordering processes. A one-dimensional superorder along the unique axis, reflected by diffuse layers perpendicular to it, dissolves at 950 °C; short-range-order maxima remain visible at 980 °C. [ABSTRACT FROM AUTHOR]

In this Letter, we explore the phase diagram and excitations of a distorted triangular lattice anti-ferromagnet. The unique two-dimensional distortion considered here is very different from the "isosce-les"-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 ɑ-CaCr204, 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. [ABSTRACT FROM AUTHOR]

We present an inelastic neutron-scattering study of phonon line shapes in the vortex state of the type II superconductor YNi2B2C. In a previous study [Phys. Rev. Lett. 101, 237002 (2008)] it was shown that certain phonons exhibit a clear signature of the superconducting gap 2&Dgr; on entering the superconducting state. Our interest was to find out whether or not the line shape of such phonons reflects the inhomogeneous nature of the vortex state induced by a magnetic field smaller than the upper critical field Bc2-We found that this is indeed the case because the observed phonon line shapes can be well described by a model considering the phonon as a local probe of the spatial variation of the superconducting gap. We found that even at B = 3 T, where the intervortex distance is less than 300 Â, the phonon line shape still shows evidence for a variation of the gap. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) on sapphire has been investigated with two different pretreatments prior to sputter deposition of the AlN layer to improve the orientation and homogeneity of the thin film. An inverse sputter etching of the substrate in argon atmosphere results in an improvement of the uniformity of the alignment of the AlN grains and hence, in enhanced electro-mechanical AlN film properties. This effect is demonstrated in the raw measurements of SAW test devices. Additionally, the impulse response of several devices shows that a poor AlN thin film layer quality leads to a higher signal damping during the transduction of energy in the inter-digital transducers. As a result, the triple-transit signal cannot be detected at the receiver. [ABSTRACT FROM AUTHOR]

The low energy magnetic excitation spectrum of charge stripe ordered La2-xSrxNiO4, x=0.4 and x=0.45 samples, were studied by neutron scattering. Two excitation modes are observed in both materials, one from the ordered magnetic moments, and a second mode consistent with pseudo-one-dimensional antiferromagnetic excitations of the charge stripe electrons (q-1D). The dispersion of the q-1D excitation follows the same relation as in x=1/3 composition, with even spectral weight in the two counterpropagating branches of the x=0.4 sample, however in the x=0.45 sample only one dispersion branch has any measurable spectral weight. The evolution of the q-1D excitations on doping to the checkerboard charge ordered phase is discussed. [ABSTRACT FROM AUTHOR]

We present a combined density functional perturbation theory and inelastic neutron scattering study of the lattice dynamical properties of YNi2B2C. In general, very good agreement was found between theory and experiment for both phonon energies and line widths. Our analysis reveals that the strong coupling of certain low energy modes is linked to the presence of large displacements of the light atoms, i.e., B and C, which is unusual in view of the rather low phonon energies. Specific modes exhibiting a strong coupling to the electronic quasiparticles were investigated as a function of temperature. Their energies and line widths showed marked changes on cooling from room temperature to just above the superconducting transition at Tc = 15.2 K. Calculations simulating the effects of temperature allow us to model the observed temperature dependence qualitatively. [ABSTRACT FROM AUTHOR]

We report an inelastic neutron scattering investigation of phonons with energies up to 159 meV in the conventional superconductor YNi2B2C. 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 Au (≈ 102 meV) and Au (≈ 159 meV) type phonon modes over the whole Brillouin zone. Despite of having linewidths of r = 10 meV, A1g modes do not strongly contribute to the total electron-phonon coupling constant A. 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. [ABSTRACT FROM AUTHOR]

Motivated by predictions of a substantial contribution of the "buckling" vibration of the CuO2 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 YBa2Cu3O7. 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. [ABSTRACT FROM AUTHOR]

Magnetic Cooper-pairing mechanisms have been proposed for heavy-fermion and cuprate superconductors; however, strong electron correlations and complications arising from a pseudogap or competing phases have precluded commonly accepted theories. In the iron arsenides, the proximity of superconductivity and antiferromagnetism in the phase diagram, the apparently weak electron–phonon coupling and the ‘resonance peak’ in the superconducting spin-excitation spectrum have also fostered the hypothesis of magnetically mediated Cooper pairing. However, as most theories of superconductivity are based on a pairing boson of sufficient spectral weight in the normal state, detailed knowledge of the spin-excitation spectrum above the superconducting transition temperature Tc is required to assess the viability of this hypothesis. Using inelastic neutron scattering we have studied the spin excitations in optimally doped BaFe1.85Co0.15As2 (Tc=25 K) over a wide range of temperatures and energies. We present the results in absolute units and find that the normal-state spectrum carries a weight comparable to that in underdoped cuprates. In contrast to cuprates, however, the spectrum agrees well with predictions of the theory of nearly antiferromagnetic metals, without the aforementioned complications. We also show that the temperature evolution of the resonance energy monotonically follows the closing of the superconducting energy gap Δ, as expected from conventional Fermi-liquid approaches. Our observations point to a surprisingly simple theoretical description of the spin dynamics in the iron arsenides and provide a solid foundation for models of magnetically mediated superconductivity. [ABSTRACT FROM AUTHOR]

Cd1−xMnxTe crystals, obtained by the high-pressure Bridgman method for x=0, 0.27, 0.49, 0.67 and 0.8, were investigated. Crystal composition was determined by electron microprobe analysis. For an Mn content lower than 0.7, a single phase of pure zinc blend structure was found. In Cd0.2Mn0.8Te samples a two-phase structure was revealed. Auger electron spectroscopy (AES) was used to determine the composition of the crystal surfaces. AES depth profiles obtained by argon sputtering and AES analysis allowed to find the distribution of Cd, Mn and Te inside the sub-surface region. Spectroscopic ellipsometry was applied to determine the complex dielectric function &epsiv; of the samples. Ellipsometric measurements were performed at room temperature in the photon energy range 0.75–6.5 eV. The spectral dependence of &epsiv; was used to find the energy gaps Eg of the alloys with different Mn content. Ellipsometric data were correlated with the compositional results obtained from the electron microprobe and AES depth profile investigations. A linear increase of energy gaps with increasing x was observed for chemically homogeneous CdMnTe crystals. [Copyright &y& Elsevier]

In recent years, the oak lace bug, Corythucha arcuata, has emerged as a significant threat to European oak forests. This species, native to North America, has in the last two decades rapidly extended its range in Europe, raising concerns about its potential impact on the continent's invaluable oak populations. To address this growing concern, we conducted an extensive study to assess the distribution, colonization patterns, and potential ecological niche of the oak lace bug in Europe. We gathered 1792 unique presence coordinates from 21 Eurasian countries, utilizing diverse sources such as research observations, citizen science initiatives, GBIF database, and social media reports. To delineate the realized niche and future distribution, we employed an ensemble species distribution modelling (SDM) framework. Two future greenhouse gas scenarios (RCP 4.5 and RCP 8.5) were considered across three-time intervals (2021-2040, 2061-2080, and 2081-2100) to project and evaluate the species' potential distribution in the future. Our analysis revealed that significant hotspots rich in host species occurrence for this invasive insect remain uninvaded so far, even within its suitable habitat. Furthermore, the native ranges of Turkey oak (Quercus cerris L.) and Hungarian oak (Quercus frainetto L.) species offer entirely suitable environments for the oak lace bug. In contrast, the pedunculate oak and sessile oak distribution ranges currently show only 40 % and 50 % suitability for colonization, respectively. However, our predictive models indicate a significant transformation in the habitat suitability of the oak lace bug, with suitability for these two oak species increasing by up to 90 %. This shift underlines an evolving landscape where the oak lace bug may exploit more of its available habitats than initially expected. It emphasises the pressing need for proactive measures to manage and stop its expanding presence, which may lead to a harmful impact on the oak population across the European landscape., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)