The interplay of Kondo screening and magnetic ordering in strongly correlated materials containing local moments is a subtle problem. Usually the number of conduction electrons per unit cell matches or exceeds the number of moments, and a Kondo-screened heavy Fermi liquid develops at low temperatures. Changing the pressure, magnetic field, or chemical doping can displace this heavy Fermi liquid in favor of a magnetically ordered state. Alternatively, Kondo singlet formation can be suppressed when the number of conduction electrons is small compared to the number of magnetic moments, known as the Kondo exhaustion scenario. Here we report the discovery of such an "exhausted" Kondo lattice material, YbIr3Si7, where the bulk electrical conductivity tends to zero in the antiferromagnetic state below the Neel temperature TN = 4.1 K, as all the free carriers are consumed in the formation of Kondo singlets. By contrast, the surface is conducting, as the Yb3+ ions relax into larger nonmagnetic Yb2+ in the presence of reduced chemical pressure, which shifts the chemical potential.

The higher dimensionality in the crystal fields of the Ce2MIn8 (M=Rh,Ir) compounds and its interplay with hybridization and disorder are key ingredients to understand the complex phase diagrams by this family, which have been explored extensively by macroscopic techniques. Here, we present an investigation of the crystal-electric field schemes of Ce2Rh1−xIrxIn8 using x-ray absorption spectroscopy. Our full multiplet calculations for the 4f1 configuration of Ce3+ to describe the temperature-dependent linear dichroism in Ce2MIn8 are consistent with a Γ71=1−α2·|∓32〉−|α|·|±52〉 ground state containing a predominant |±3/2〉 contribution that increases further with x. This enhancement is believed to favor superconductivity in Ce-based heavy fermion materials, observed in previous results in the CeMIn5 family. Our recent observations shed light on the unexpected emergence of the ambient-pressure superconducting dome in the center of the composition phase diagram and its subsequent suppression on the Ir-rich side due to the early onset of fluctuations associated with the structurally more disordered state, inferred from previous neutron magnetic diffraction experiments. Published by the American Physical Society 2024

FexTe thin films were prepared on SrTiO3 (001) substrates by molecular beam epitaxy in a well-ordered epitaxial layer-by-layer fashion. The composition of the films was varied by adjusting the Te flux in a Te-limited growth regime. Changes in the electronic structure were systematically studied using in situ x-ray absorption spectroscopy at the Fe L 2,3 and Te M 4,5 edges and x-ray photoelectron spectroscopy of core levels and valence band. We found that FeTe with optimized composition (Fe/Te ratio approximate to 1) provides the sharpest spectral features, indicating that Fe1.00Te can be synthesized as a thin film, although it is not possible in bulk.

We present a comprehensive study of CaCu$_3$Ru$_4$O$_{12}$ using bulk sensitive hard and soft x-ray spectroscopy combined with local-density approximation (LDA) + dynamical mean-field theory (DMFT) calculations. Correlation effects on both the Cu and Ru ions can be observed. From the Cu $2p$ core level spectra we deduce the presence of magnetic Cu$^{2+}$ ions hybridized with a reservoir of itinerant electrons. The strong photon energy dependence of the valence band allows us to disentangle the Ru, Cu, and O contributions and thus to optimize the DMFT calculations. The calculated spin and charge susceptibilities show that the transition metal oxide CaCu$_3$Ru$_4$O$_{12}$ must be classified as a Kondo system and that the Kondo temperature is in the range of 500-1000 K.

ReO${}_{3}$ is a remarkable transition metal oxide in that it has the highest conductivity of all oxides, comparable even with that of silver. Using state of the art bulk-sensitive angle-resolved photoelectron spectroscopy, the authors are able to observe clear dispersions of the Re 5$d$ and O 2$p$ derived bands as well as the momentum splitting of the Fermi surface due to the Re 5$d$ spin-orbit interaction. The experimental results are compared quantitatively to density functional theory band structure calculations, thereby providing a deeper understanding of the material class of the 5$d$ oxides.

We report our study about the growth and characterization of Bi2Te3 thin films on top of Y3Fe5O12 (111), Tm3Fe5O12 (111), Fe3O4 (111), and Fe3O4 (100) single-crystal substrates. Using molecular-beam epitaxy, we were able to prepare the topological insulator/ferromagnetic insulator heterostructures with no or minimal chemical reaction at the interface. We observed the anomalous Hall effect on these heterostructures and also a suppression of the weak antilocalization in the magnetoresistance, indicating a topological surface-state gap opening induced by the magnetic proximity effect. However, we did not observe any obvious x-ray magnetic circular dichroism (XMCD) on the Te M-45 edges. The results suggest that the ferromagnetism induced by the magnetic proximity effect via van der Waals bonding in Bi2Te3 is too weak to be detected by XMCD, but still can be observed by electrical transport measurements. This is in fact not inconsistent with reported density-functional calculations on the size of the gap opening.

We have synthesized Fe1+y Te thin films by means of molecular beam epitaxy (MBE) under Te-limited growth conditions. We found that epitaxial layer-by-layer growth is possible for a wide range of excess Fe values, wider than expected from what is known from studies on the bulk material. Using x-ray magnetic circular dichroism spectroscopy at the Fe L-2(,3) and Te M-4(,5) edges, we observed that films with high excess Fe contain ferromagnetic clusters while films with lower excess Fe remain nonmagnetic. Moreover, x-ray absorption spectroscopy showed that it is possible to obtain films with very similar electronic structure as that of a high quality bulk single crystal Fe-1.(14) Te. Our results suggest that MBE with Te-limited growth may provide an opportunity to synthesize FeTe films with smaller amounts of excess Fe as to come closer to a possible superconducting phase.

A Neissaria bacterial pilus sugar, bacillosamine, was synthesized and, for the first time, used as a probe to screen a single-chain variable fragment (scFv).

We present inelastic neutron scattering measurements on the ruthenate Sr 1 . 6 Ba 0 . 4 RuO 4 which is on the hitherto almost unknown Ba-substituted side of the doping phase diagram of Sr 2 − x Ae x RuO 4 ( Ae = Ca, Ba). Unlike the Ca-substituted side of the phase diagram no (quasi)static magnetic peaks can be observed in Sr 1 . 6 Ba 0 . 4 RuO 4 . Instead, incommensurate spin fluctuations can be observed around q 0 = ( ± 0 . 3 , ± 0 . 3 , 0). Both the absolute intensity of χ (cid:2)(cid:2) ( Q ,ω ) and its energy and temperature dependence as well as the anisotropy ratio χ (cid:2)(cid:2) c /χ (cid:2)(cid:2) a,b resemble the ones in Sr 2 RuO 4 . Hence, a random potential implied by the substitution of huge Ba ions as well as the induced increase of interatomic distances has less impact on the magnetic properties than octahedral tilts implied by Ca substitution. Moreover, any ferromagnetic spin fluctuations are either absent in Sr 1 . 6 Ba 0 . 4 RuO 4 or below the detection limit.

We report on the exploration to synthesize Sr2−xBaxRuO4, the large volume variant of the unconventional superconductor Sr2RuO4. We have succeeded in growing single crystals for x-values up to 0.4 by making use of the traveling solvent floating zone method. The quality of the obtained crystals is confirmed by X-ray and neutron diffraction measurements and the properties of these Ba-substituted ruthenates were studied with magnetic and electrical transport measurements.

Objectives. - A carbapenem-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex (CRA complex) infection is one of most the difficult infections to control worldwide. We evaluated the long-term effects of infection control interventions on the incidence densities of healthcare-associated infection (HAT) and CRA complex infection, and the rates of Acinetobacter calcoaceticus-Acinetobacter baumannii complex bacteremia (AB).Patients and methods. - We performed a cross-sectional analysis at the Changhua Christian Hospital from January 2002 to December 2013. Interventions for infection control were implemented from 2002 to 2009 (period 1). From 2010 to 2013 (period 2), infection control programs were improved by in-service education and a hand hygiene campaign to prepare for international and national hospital accreditation. The effectiveness of infection and antibiotic control programs was assessed according to the incidence densities of HAT and CRA complex, rates of CRA complex and of AB, chlorhexidine consumption density, and defined daily dose of antibiotics.Results. - The incidence density of HAT decreased from 4.56 parts per thousand to 1.52 parts per thousand from periods 1 to 2 (P < 0.001). Likewise, the incidence of AB decreased from 177.79 to 137.76 per person-years per 100,000 admissions (P < 0.001). The incidence density of CRA complex ranged from 3.17-7.38 parts per thousand. The chlorhexidine consumption density increased from 5.5 to 45.5 L per 1000 patient-days (P < 0.001). The consumption of piperacillin-tazobactam was lower in period 2 than in period 1 (P < 0.001).Conclusion. - Education for infection control programs, hand hygiene campaigns, and antibiotics control programs may decrease the incidence density of AB and HAT, and may help control

This study investigated the in vitro susceptibilities of methicillin-resistant Staphylococcus aureus (MRSA) to nine antimicrobial agents in Taiwan. A total of 1,725 isolates were obtained from 20 hospitals throughout Taiwan from 2006 to 2010. The minimum inhibitory concentrations (MICs) of the nine agents were determined by the agar dilution method. The MICs of mupirocin and tyrothricin were determined for 223 MRSA isolates collected from 2009 to 2010. For vancomycin, 99.7 % were susceptible; however, 30.0 % (n = 517) exhibited MICs of 2 μg/ml and 0.3 % (n = 6) demonstrated intermediate susceptibility (MICs of 4 μg/ml). Nearly all isolates (≥99.9 %) were susceptible to teicoplanin, linezolid, and daptomycin. The MIC90 values were 2 μg/ml for ceftobiprole and 1 μg/ml for nemonoxacin. The MIC90 values of mupirocin and tyrothricin were 0.12 and 4 μg/ml, respectively. MIC creep was noted for daptomycin during this period, but not for vancomycin, teicoplanin, linezolid, or tigecycline. For isolates with vancomycin MICs of 2 μg/ml, the MIC90 values were 2 μg/ml for teicoplanin, 0.5 μg/ml for daptomycin, and 0.5 μg/ml for tigecycline. Those values were four- to eight-fold higher than those among isolates with vancomycin MICs of 0.5 μg/ml (2, 0.06, and 0.12 μg/ml, respectively). Of the nine MRSA isolates exhibiting non-susceptibility to vancomycin (n = 6), teicoplanin (n = 1), daptomycin (n = 2), or tigecycline (n = 1), all had different pulsotypes, indicating the absence of intra-hospital or inter-hospital spread. The presence of a high proportion of MRSA isolates with elevated MICs (2 μg/ml) and MIC creep of daptomycin might alert clinicians on the therapy for serious MRSA infections in Taiwan.

A new iterative one-pot sequential method for the solution-phase synthesis of oligosaccharides has been devised on the basis of the electrochemical oxidation of a propagating thioglycoside terminus to generate the corresponding triflate, followed by the reaction with a thioglycoside building block having a free hydroxyl group. A practical automated synthesizer was developed for the method and was effectively used for assembling up to six thioglycoside building blocks to synthesize partial structures of poly-β-D-(1-6)-N-acetylglucosamine.

BACKGROUND:The current study investigated risk factor related to gram-negative bacterial (GNB) infection by Acinetobacter baumannii and non-A baumannii groups, in liver transplantation (OLT) recipients.MATERIALS AND METHODS:All patients with OLT and their living donors were analyzed retrospectively. After excluding those with Gram-positive and fungal infections 89 patients remained in the study including 59 who were noninfected and 30 with GNB infection. The risk factors for GNB infection were classified into the preoperative versus the postoperative periods.RESULTS:GNB-infected patients were classified as non-A baumannii versus A baumannii (15 patients per group). A significant difference was observed in the numbers of intensive care and hospitalized days, hemodialysis requirement, and reoperation frequency compared with the noninfected group. Infection also correlated with hospital mortality, overall survival, and Model for End-Stage Liver Disease (MELD) scores with significance upon univariate but only the last feature on multivariate analysis.CONCLUSIONS:Preoperative MELD scores were more likely to be higher among the non-A baumannii compared with the A baumannii-infected group. However, the 1-year survival of the A baumannii-infected subjects was lower than that of the non-A baumannii infected group.