Synthesis and Crystal Structure of the Europium(II) Hydride Oxide Iodide Eu5H2O2I4 Showing Blue-Green Luminescence.

As the first europium(II) hydride oxide iodide, dark red single crystals of Eu5H2O2I4 could be synthesized from oxygen-contaminated mixtures of EuH2 and EuI2. Its orthorhombic crystal structure (a = 1636.97(9) pm, b = 1369.54(8) pm, c = 604.36(4) pm, Z = 4) was determined via single-crystal X-ray diffraction in the space group Cmcm. Anion-centred tetrahedra [HEu4]7+ and [OEu4]6+ serve as central building blocks interconnected via common edges to infinite ribbons parallel to the c axis. These ribbons consist of four trans-edge connected (Eu2+)4 tetrahedra as repetition unit, two H--centred ones in the inner part, and two O2--centred ones representing the outer sides. They are positively charged, according to ∞1{[Eu5H2O2]4+}, to become interconnected and charge-balanced by iodide anions. Upon excitation with UV light, the compound shows blue-green luminescence with the shortest Eu2+ emission wavelength ever observed for a hydride derivative, peaking at 463 nm. The magnetic susceptibility of Eu5H2O2I4 follows the Curie-Weiss law down to 100 K, and exhibits a ferromagnetic ordering transition at about 10 K.

Association of Long-term Statin Use With the Risk of Intracerebral Hemorrhage: A Danish Nationwide Case-Control Study.

BACKGROUND AND OBJECTIVES: A causal relationship between long-term statin use and the risk of intracerebral hemorrhage (ICH) remains uncertain. We investigated the association between statin use prior to hospital admission for ICH in a Danish population-based, nationwide case-control study. METHODS: We used the Danish Stroke Registry to identify all patients age ≥45-years with a first-ever ICH between 2005-2018. ICH cases were matched for age, sex, and calendar year to controls selected from the general population. A medication registry with information on all dispensed prescriptions at community pharmacies in Denmark since 1995 was used to ascertain prior statin exposure that was classified for recency, duration, and intensity. Using conditional regression and adjusting for potential confounders, we calculated adjusted odds ratios (aORs) and corresponding 95% confidence intervals (CIs) for the risk of ICH. RESULTS: The study population consisted of 16,235 patients with ICH and 640,943 controls. Current statin use (cases 25.9% vs controls 24.5%; aOR 0.74, 95% CI, 0.71-0.78) and longer duration of current statin use (<1 year: aOR 0.86; 95%CI, 0.81-0.92; ≥1 to <5 years: aOR 0.72; 95%CI, 0.68-0.76; ≥5 to <10 years: aOR 0.65; 95%CI, 0.60-0.71; ≥10 years of use, 0.53; 95%CI 0.45-0.62; P for trend <0.001) were associated with lower risk of ICH. Similar treatment duration relationships were found in analyses stratified by statin use intensity (high intensity therapy: <1 year of use, aOR 0.78; 95%CI, 0.66-0.93; ≥10 years of use: 0.46; 95% CI 0.33-0.65; P for trend 0.001). DISCUSSION: We found that longer duration of statin use is associated with a lower risk of ICH. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that current statin use and longer duration of statin use are each associated with a lower risk of ICH.

Sub-nanosecond acousto-electric carrier redistribution dynamics and transport in polytypic GaAs nanowires.

The authors report on a combined structural, optical and acousto-electric study of polytypic GaAs nanowires. Two types of nanowires with different zincblende and wurtzite crystal phase mixing are identified by transmission electron microscopy and photoluminescence spectroscopy. The nanowires exhibit characteristic recombination channels which are assigned to different types of spatially direct recombination (electron and hole within the same crystal phase segment) and spatially indirect recombination (electron and holes localized in different segments). Contact-free acousto-optoelectric spectroscopy is employed to resolve spatiotemporal charge carrier dynamics between different recombination channels induced by a piezoelectric surface acoustic wave. The observed suppression of the emission and its dynamic temporal modulation shows unambiguous fingerprints of the local bandedge variations induced by the crystal phase mixing. A nanowire, which exhibits a variation from a near-pristine zinc blende crystal structure to a highly mixed crystal phase, shows a clear dependence on the propagation direction of the acoustic wave. In contrast, no pronounced directionality is found for a nanowire with an extended near-pristine zincblende segment. The experimental findings are corroborated by solving the drift and diffusion equations of electrons and holes induced by the surface acoustic wave. The key characteristics observed in our experimental data are well reproduced in the numerical simulations by assuming two general bandedge modulations and realistic parameters for the bandedge discontinuities and transport mobilities of electrons and holes. This evidences that even all relevant physical processes are accounted for in the model.

Ultrafast electron cycloids driven by the transverse spin of a surface acoustic wave.

Spin-momentum locking is a universal wave phenomenon promising for applications in electronics and photonics. In acoustics, Lord Rayleigh showed that surface acoustic waves exhibit a characteristic elliptical particle motion strikingly similar to spin-momentum locking. Although these waves have become one of the few phononic technologies of industrial relevance, the observation of their transverse spin remained an open challenge. Here, we observe the full spin dynamics by detecting ultrafast electron cycloids driven by the gyrating electric field produced by a surface acoustic wave propagating on a slab of lithium niobate. A tubular quantum well wrapped around a nanowire serves as an ultrafast sensor tracking the full cyclic motion of electrons. Our acousto-optoelectrical approach opens previously unknown directions in the merged fields of nanoacoustics, nanophotonics, and nanoelectronics for future exploration.

Disseminated Mycobacterium abscessus infection and native valve endocarditis.

Mycobacterium abscessus is a rapidly growing mycobacterium. It rarely causes disseminated infection or endocarditis. A 55-year-old male with a history of hepatitis C, liver cirrhosis, intravenous drug use (last use was four years ago), and chronic back pain presented with a three-week history of a right calf nodular lesion. He did not have a fever, chills, rash, dyspnea, or cough. Laboratory data showed mild leukocytosis. Computed tomography of the chest revealed bilateral cavitating nodules. Skin biopsy, sputum, and blood cultures grew Mycobacterium abscessus. Therapy with meropenem, tigecycline, and amikacin was initiated. He was re-admitted with worsening lower back pain. A lumbar magnetic resonance imaging showed destructive changes of L4 and L5 vertebral bodies concerning for osteomyelitis. Blood culture and bone biopsy grew Mycobacterium abscessus again. An echocardiogram was performed due to persistent bacteremia, which revealed large vegetation on the tricuspid valve and small vegetation on the mitral valve. Therapy was changed to eight weeks of amikacin, with cefoxitin and imipenem for twelve months based on drug susceptibility. Treatment of disseminated Mycobacterium abscessus is challenging due to antibiotic resistance. Typically, multidrug therapy is warranted with at least three active drugs. In severe valvular endocarditis, valve replacement may be required.

Paraganglioma of the middle mediastinum.

A 60-year-old female was evaluated for significant weight loss, nausea, vomiting, and dysphagia. A computed tomography (CT) of the chest showed a 3 cm mass in the middle mediastinum. CT scan of the abdomen and pelvis revealed no abnormality. Positron emission tomography (PET) of the whole body revealed tracer uptake in the pre-carinal nodal mass. There were no other suspicious foci of tracer uptake. Mediastinoscopy and biopsy revealed a well-differentiated low-grade neuroendocrine tumor. She underwent sternotomy, and after careful mobilization of the great vessels, the middle mediastinal mass was successfully resected. Final pathology revealed a paraganglioma with no morphological signs to suggest malignancy. The right lower paratracheal lymph node did not show any tumor cells. She did well postoperatively.

Cavitating pulmonary metastases from a renal cell carcinoma.

Cavitary lung lesions are quite common findings on chest imaging and often pose a diagnostic challenge to the clinicians. We describe a case of a 75-year-old male who presented to the emergency room with hemoptysis. Computed tomography of the chest demonstrated multiple cavitary pulmonary nodules with peripheral groundglass opacities. Bronchoscopy did not reveal any active bleeding source, and washings were negative for malignancy and infectious cause. Computed Tomography guided biopsy of the left lung nodule showed metastatic carcinoma consistent with papillary renal cell carcinoma. This case highlights the unusual presentation of metastatic renal cell carcinoma.

Breakdown of Corner States and Carrier Localization by Monolayer Fluctuations in Radial Nanowire Quantum Wells.

We report a comprehensive study of the impact of the structural properties in radial GaAs-Al0.3Ga0.7As nanowire-quantum well heterostructures on the optical recombination dynamics and electrical transport properties, emphasizing particularly the role of the commonly observed variations of the quantum well thickness at different facets. Typical thickness fluctuations of the radial quantum well observed by transmission electron microscopy lead to pronounced localization. Our optical data exhibit clear spectral shifts and a multipeak structure of the emission for such asymmetric ring structures resulting from spatially separated, yet interconnected quantum well systems. Charge carrier dynamics induced by a surface acoustic wave are resolved and prove efficient carrier exchange on native, subnanosecond time scales within the heterostructure. Experimental findings are corroborated by theoretical modeling, which unambiguously show that electrons and holes localize on facets where the quantum well is the thickest and that even minute deviations of the perfect hexagonal shape strongly perturb the commonly assumed 6-fold symmetric ground state.

Health-Related Genetic Direct-to-Consumer Tests in the German Setting: The Available Offer and the Potential Implications for a Solidarily Financed Health-Care System.

BACKGROUND: The global genetic direct-to-consumer (DTC) market will reach a volume of USD 230 billion in 2018. The expenditures for this genetic analysis are borne by the customer, whereas consequential costs may arise for a solidarily financed system. In a first step, it is essential to gain an overview of the currently available offer in the German setting. METHODS: In April 2016, we conducted a systematic internet search in the Google search engine. In November 2016, we updated the information of the webpages in terms of country, language, types of health-related tests, additional offer of non-health-related DTC test, information about sensitivity and specificity, certification and accreditation, costs as well as reference to German Act on Genetic Testing. RESULTS: Thirty-five webpages were included in the final overview. A plurality of different predictive analysis options was identified. Price information was not available for all offered genetic analyses. Costs for predictive analysis in one disease vary between EUR 90 and 990, for predictive package analysis between EUR 232.18 and 375, and for genetic lifestyle analysis between EUR 84.55 and 570.20. CONCLUSIONS: Genetic results may lead to uncertainty and anxiety; therefore, subsequent costs for a solidarily financed system may arise. Genetic DTC tests may have an influence on different players on the micro-, meso- and macro-levels, which may have a cost-cutting or cost-increasing effect on health-care expenditures. The increased interest in genetic analysis as well as the possibility of worldwide internet-based access to genetic tests requires population-wide education.

Crystal Phase Quantum Dots in the Ultrathin Core of GaAs-AlGaAs Core-Shell Nanowires.

Semiconductor quantum dots embedded in nanowires (NW-QDs) can be used as efficient sources of nonclassical light with ultrahigh brightness and indistinguishability, needed for photonic quantum information technologies. Although most NW-QDs studied so far focus on heterostructure-type QDs that provide an effective electronic confinement potential using chemically distinct regions with dissimilar electronic structure, homostructure NWs can localize excitons at crystal phase defects in leading to NW-QDs. Here, we optically investigate QD emitters embedded in GaAs-AlGaAs core-shell NWs, where the excitons are confined in an ultrathin-diameter NW core and localized along the axis of the NW core at wurtzite (WZ)/zincblende (ZB) crystal phase defects. Photoluminescence (PL)-excitation measurements performed on the QD-emission reveal sharp resonances arising from excited electronic states of the axial confinement potential. The QD-like nature of the emissive centers are suggested by the observation of a narrow PL line width, as low as ~300 µeV, and confirmed by the observation of clear photon antibunching in autocorrelation measurements. Most interestingly, time-resolved PL measurements reveal a very short radiative lifetime <1 ns, indicative of a transition from a type-II to type-I band alignment of the WZ/ZB crystal interface in GaAs due to the strong quantum confinement in the ultrathin NW core.

Tunable quantum confinement in ultrathin, optically active semiconductor nanowires via reverse-reaction growth.

A unique growth scheme is demonstrated to realize ultrathin GaAs nanowires on Si with sizes down to the sub-10 nm regime. While this scheme preserves the bulk-like crystal properties, correlated optical experiments reveal huge blueshifted photo-luminescence (up to ≈100 meV) with decreasing nanowire cross-section, demonstrating very strong quantum confinement effects.

Dynamic acoustic control of individual optically active quantum dot-like emission centers in heterostructure nanowires.

We probe and control the optical properties of emission centers forming in radial heterostructure GaAs-Al0.3Ga0.7As nanowires and show that these emitters, located in Al0.3Ga0.7As layers, can exhibit quantum-dot like characteristics. We employ a radio frequency surface acoustic wave to dynamically control their emission energy, and occupancy state on a nanosecond time scale. In the spectral oscillations, we identify unambiguous signatures arising from both the mechanical and electrical component of the surface acoustic wave. In addition, different emission lines of a single emission center exhibit pronounced anticorrelated intensity oscillations during the acoustic cycle. These arise from a dynamically triggered carrier extraction out of the emission center to a continuum in the radial heterostructure. Using finite element modeling and Wentzel-Kramers-Brillouin theory we identify quantum tunneling as the underlying mechanism. These simulation results quantitatively reproduce the observed switching and show that in our systems these emission centers are spatially separated from the continuum by >10.5 nm.

Lasing from individual GaAs-AlGaAs core-shell nanowires up to room temperature.

Semiconductor nanowires are widely considered to be the next frontier in the drive towards ultra-small, highly efficient coherent light sources. While NW lasers in the visible and ultraviolet have been widely demonstrated, the major role of surface and Auger recombination has hindered their development in the near infrared. Here we report infrared lasing up to room temperature from individual core-shell GaAs-AlGaAs nanowires. When subject to pulsed optical excitation, NWs exhibit lasing, characterized by single-mode emission at 10 K with a linewidth <60 GHz. The major role of non-radiative surface recombination is obviated by the presence of an AlGaAs shell around the GaAs-active region. Remarkably low threshold pump power densities down to ~760 W cm(-2) are observed at 10 K, with a characteristic temperature of T(0)=109±12 K and lasing operation up to room temperature. Our results show that, by carefully designing the materials composition profile, high-performance infrared NW lasers can be realised using III/V semiconductors.

High mobility one- and two-dimensional electron systems in nanowire-based quantum heterostructures.

Free-standing semiconductor nanowires in combination with advanced gate-architectures hold an exceptional promise as miniaturized building blocks in future integrated circuits. However, semiconductor nanowires are often corrupted by an increased number of close-by surface states, which are detrimental with respect to their optical and electronic properties. This conceptual challenge hampers their potentials in high-speed electronics and therefore new concepts are needed in order to enhance carrier mobilities. We have introduced a novel type of core-shell nanowire heterostructures that incorporate modulation or remote doping and hence may lead to high-mobility electrons. We demonstrate the validity of such concepts using inelastic light scattering to study single modulation-doped GaAs/Al0.16Ga0.84As core-multishell nanowires grown on silicon. We conclude from a detailed experimental study and theoretical analysis of the observed spin and charge density fluctuations that one- and two-dimensional electron channels are formed in a GaAs coaxial quantum well spatially separated from the donor ions. A total carrier density of about 3 × 10(7) cm(-1) and an electron mobility in the order of 50,000 cm(2)/(V s) are estimated. Spatial mappings of individual GaAs/Al0.16Ga0.84As core-multishell nanowires show inhomogeneous properties along the wires probably related to structural defects. The first demonstration of such unambiguous 1D- and 2D-electron channels and the respective charge carrier properties in these advanced nanowire-based quantum heterostructures is the basis for various novel nanoelectronic and photonic devices.

Spontaneous alloy composition ordering in GaAs-AlGaAs core-shell nanowires.

By employing various high-resolution metrology techniques we directly probe the material composition profile within GaAs-Al0.3Ga0.7As core-shell nanowires grown by molecular beam epitaxy on silicon. Micro Raman measurements performed along the entire (>10 µm) length of the [111]-oriented nanowires reveal excellent average compositional homogeneity of the nominally Al0.3Ga0.7As shell. In strong contrast, along the radial direction cross-sectional scanning transmission electron microscopy and associated chemical analysis reveal rich structure in the AlGaAs alloy composition due to interface segregation, nanofaceting, and local alloy fluctuations. Most strikingly, we observe a 6-fold Al-rich substructure along the corners of the hexagonal AlGaAs shell where the Al-content is up to x ~ 0.6, a factor of 2 larger than the body of the AlGaAs shell. This is associated with facet-dependent capillarity diffusion due to the nonplanarity of shell growth. A modulation of the Al-content is also found along the radial [110] growth directions of the AlGaAs shell. Besides the ~10(3)-fold enhancement of the photoluminescence yield due to inhibition of nonradiative surface recombination, the AlGaAs shell gives rise to a broadened band of sharp-line luminescence features extending ~150-30 meV below the band gap of Al0.3Ga0.7As. These features are attributed to deep level defects under influence of the observed local alloy fluctuations in the shell.

Direct observation of a noncatalytic growth regime for GaAs nanowires.

We identify a new noncatalytic growth regime for molecular beam epitaxially grown GaAs nanowires (NWs) that may provide a route toward axial heterostructures with discrete material boundaries and atomically sharp doping profiles. Upon increase of the As/Ga flux ratio, the growth mode of self-induced GaAs NWs on SiO(2)-masked Si(111) is found to exhibit a surprising discontinuous transition in morphology and aspect ratio. For effective As/Ga ratios <1, in situ reflection high-energy electron diffraction measurements reveal clear NW growth delay due to formation of liquid Ga droplets since the growth proceeds via the vapor-liquid-solid mechanism. In contrast, for effective As/Ga ratios >1 an immediate onset of NW growth is observed indicating a transition to droplet-free, facet-driven selective area growth with low vertical growth rates. Distinctly different microstructures, facet formation and either the presence or absence of Ga droplets at the apex of NWs, are further elucidated by transmission electron microscopy. The results show that the growth mode transition is caused by an abrupt change from As- to Ga-limited conditions at the (111)-oriented NW growth front, allowing precise tuning of the dominant growth mode.

Directional and dynamic modulation of the optical emission of an individual GaAs nanowire using surface acoustic waves.

We report on optical experiments performed on individual GaAs nanowires and the manipulation of their temporal emission characteristics using a surface acoustic wave. We find a pronounced, characteristic suppression of the emission intensity for the surface acoustic wave propagation aligned with the axis of the nanowire. Furthermore, we demonstrate that this quenching is dynamical as it shows a pronounced modulation as the local phase of the surface acoustic wave is tuned. These effects are strongly reduced for a surface acoustic wave applied in the direction perpendicular to the axis of the nanowire due to their inherent one-dimensional geometry. We resolve a fully dynamic modulation of the nanowire emission up to 678 MHz not limited by the physical properties of the nanowires.