Elastic properties of single crystal Bi12SiO20 as a function of pressure and temperature and acoustic attenuation effects in Bi12 MO20 (M = Si, Ge and Ti)

A comprehensive study of sillenite Bi12SiO20 single-crystal properties, including elastic stiffness and piezoelectric coefficients, dielectric permittivity, thermal expansion and molar heat capacity, is presented. Brillouin-interferometry measurements (up to 27 GPa), which were performed at high pressures for the first time, and ab initio calculations based on density functional theory (up to 50 GPa) show the stability of the sillenite structure in the investigated pressure range, in agreement with previous studies. Elastic stiffness coefficients c 11 and c 12 are found to increase continuously with pressure while c 44 increases slightly for lower pressures and remains nearly constant above 15 GPa. Heat-capacity measurements were performed with a quasi-adiabatic calorimeter employing the relaxation method between 2 K and 395 K. No phase transition could be observed in this temperature interval. Standard molar entropy, enthalpy change and Debye temperature are extracted from the data. The results are found to be roughly half of the previous values reported in the literature. The discrepancy is attributed to the overestimation of the Debye temperature which was extracted from high-temperature data. Additionally, Debye temperatures obtained from mean sound velocities derived by Voigt-Reuss averaging are in agreement with our heat-capacity results. Finally, a complete set of electromechanical coefficients was deduced from the application of resonant ultrasound spectroscopy between 103 K and 733 K. No discontinuities in the temperature dependence of the coefficients are observed. High-temperature (up to 1100 K) resonant ultrasound spectra recorded for Bi12 MO20 crystals revealed strong and reversible acoustic dissipation effects at 870 K, 960 K and 550 K for M = Si, Ge and Ti, respectively. Resonances with small contributions from the elastic shear stiffness c 44 and the piezoelectric stress coefficient e 123 are almost unaffected by this dissipation. © 2020 The Author(s). Published by IOP Publishing Ltd

Erectile dysfunction: role of computed tomography cavernosography in the diagnosis and treatment planning of venous leak.

BACKGROUND Venous leak appears to be the most common cause of vasculogenic erectile dysfunction (ED), which can be treated with venous embolization. Traditionally, conventional cavernosography was used for the diagnosis and treatment planning of venous leak. Recently, computed tomography (CT) cavernosography was introduced as a novel cross-sectional imaging method proposed to be advantageous over conventional cavernosography. We created a novel management algorithm for diagnosing venous leak including CT cavernosography as an imaging modality. In order to provide a broader basis for our management algorithm, a systematic literature review was conducted. MAIN BODY In this article we systematically review relevant literature on using CT cavernosography for the diagnosis and treatment planning in ED patients with venous leak following the PRISMA selection process. Nine full-text articles were included in the review and assigned a level of evidence grade (all grade II). Two studies (2/9) compared the results of conventional cavernosography with those of CT cavernosography which was superior for site-specific venous leak identification (19.4% vs. 100%, respectively). CT cavernosography is a more detailed imaging method that is faster to perform, exposes the patient to less radiation, and requires less contrast material. In one study (1/9), CT cavernosography was used for diagnostic purposes only. Eight studies (8/9) cover both, diagnostic imaging and treatment planning including embolization (1/9) and sclerotherapy (2/9) of venous leak in patients with venogenic ED. Three studies (3/9) describe anatomical venous leak classifications that were established based on CT cavernosography findings for accurate mapping of superficial and/or deep venous leak and identification of mixed or more complex forms of venous leak present in up to 84% of patients. In addition to treatment planning, one study (1/9) used CT cavernosography also for follow-up imaging post treatment. CONCLUSION CT cavernosography is superior to conventional cavernosography for diagnosis and treatment planning in patients with ED caused by venous leak (grade II levels of evidence). Consequently, CT cavernosography should be included in management algorithms for ED patients with suspected venous leak

Tuning the Morphological Appearance of Iron(III) Fumarate: Impact on Material Characteristics and Biocompatibility

Iron(III) fumarate materials are well suited for biomedical applications as they feature biocompatible building blocks, porosity, chemical functionalizability, and magnetic resonance imaging (MRI) activity. The synthesis of these materials however is difficult to control, and it has been challenging to produce monodisperse particle sizes and morphologies that are required in medical use. Here, we report the optimization of iron(III) fumarate nano- and microparticle synthesis by surfactant-free methods, including room temperature, solvothermal, microwave, and microfluidic conditions. Four variants of iron(III) fumarate with distinct morphologies were isolated and are characterized in detail. Structural characterization shows that all iron(III) fumarate variants exhibit the metal–organic framework (MOF) structure of MIL-88A. Nanoparticles with a diameter of 50 nm were produced, which contain crystalline areas not exceeding 5 nm. Solvent-dependent swelling of the crystalline particles was monitored using in situ X-ray diffraction. Cytotoxicity experiments showed that all iron(III) fumarate variants feature adequate biotolerability and no distinct interference with cellular metabolism at low concentrations. Magnetic resonance relaxivity studies using clinical MRI equipment, on the other hand, proved that the MRI contrast characteristics depend on particle size and morphology. All in all, this study demonstrates the possibility of tuning the morphological appearance of iron(III) fumarate particles and illustrates the importance of optimizing synthesis conditions for the development of new biomedical materials

Thermoelastic anomalies in selected spinel- and perovskite-type single crystal substrate materials

Einkristallines NdScO$_3$, SmScO$_3$, TbScO$_3$, DyScO$_3$ ($\it RE$ScO$_3$) und NdGaO$_3$ mit Perowskitstruktur sowie MgGa$_2$O$_4$ mit Spinellstruktur sind bedeutende Substratmaterialien zur Epitaxie dünner Schichten. In dieser Arbeit werden thermoelastische Eigenschaften dieser Phasen charakterisiert und strukturell interpretiert. Ein glasartiger Übergang in der Kationenordnung von MgGa$_2$O$_4$ spiegelt sich in Knicken im Temperaturverlauf der thermischen Dehnung und elastischer Steifigkeiten wider. Die Anisotropie der Steifigkeit der Perowskite bildet bei hohen Temperaturen zunehmend höhere Symmetrien aus; die Phasen schmelzen, bevor die zugehörigen strukturellen Symmetrien realisiert werden können. Der Tieftemperaturverlauf von Scherwiderständen der REScO3 zeigt strukturelle Instabilitäten auf, die bisher keine nachgewiesenen Phasenumwandlungen aktiviert haben. Die Steifigkeiten anderer $\it RE$ScO$_3$ und $\it RE$GaO$_3$ werden vorhergesagt und die Anisotropie der thermischen Dehnung innerhalb dieser Stoffgruppen interpretiert.Single-crystal NdScO$_3$, SmScO$_3$, TbScO$_3$, DyScO$_3$ ($\it RE$ScO$_3$) and NdGaO$_3$ with perovskite-type structure and MgGa2O4 with spinel-type structure are important substrate materials for epitaxial thin film growth. In this work, thermoelastic properties of these phases are characterized and interpreted structurally. A glass-like transition in the cation distribution of MgGa$_2$O$_4$ is reflected in kinks of the temperature evolution of its thermal expansion and elastic stiffnesses. At high temperatures, the anisotropy of the elastic stiffness of the perovskite phases increasingly develops higher symmetries but the materials melt before the associated structural symmetries can be realized. The temperature coefficients of some shear stiffnesses of the REScO3 at low temperatures reveal structural instabilities that have not activated known phase transitions yet. The stiffnesses of other $\it RE$ScO$_3$ und $\it RE$GaO$_3$ are predicted and the anisotropy of thermal expansion within these groups of materials is interpreted