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Physical review / B 97(13), 134111 (2018). doi:10.1103/PhysRevB.97.134111, The high-pressure behavior of monoclinic $(P2_{1}/c)\alpha$-chalcocite, $\mathrm{Cu_{2}}S$, was investigated at ambient temperature by single-crystal x-ray diffraction, electrical resistance measurements, and optical absorption spectroscopy up to 16 GPa. The experiments were complemented by density-functional-theory-based calculations. Single-crystal x-ray diffraction data show that monoclinic $\alpha$-chalcocite undergoes two pressure-induced first-order phase transitions at ∼3.1 and ∼7.1 GPa. The crystal structure of the first high-pressure polymorph, HP1, was solved and refined in space group $P2_{1}/c$ with $a=10.312(4)Å, b=6.737(3)Å, c=7.305(1)Å$, and β=$100.17(2)∘$ at 6.2(3) GPa. The crystal structure of the second high-pressure polymorph, HP2, was solved and refined in space group $P2_{1}/c$ with $a=6.731(4)Å, b=6.689(2)Å, c=6.967(8)Å$, and β=$93.18(3)∘$ at 7.9(4) GPa. Electrical resistance measurements upon compression and optical absorption experiments upon decompression show that the structural changes in α-chalcocite are accompanied by changes of the electrical and optical properties. Upon pressure release, the band gap $Eg$ of $\alpha$-chalcocite (1.24 eV at ambient conditions) widens across the first structural phase transition, going from 1.24 eV at 2.2 GPa (α-chalcocite) to 1.35 eV at 2.6 GPa (HP1), and closes significantly across the second phase transition, going from 1.32 eV at 4.4 GPa (HP1) to 0.87 eV at 4.9 GPa (HP2). The electrical resistance shows similar behavior: its highest value is for the first high-pressure polymorph (HP1), and its lowest value is for the second high-pressure polymorph (HP2) of $\alpha$-chalcocite. These results are interpreted on the basis of calculated electronic band structures., Published by APS, Woodbury, NY

First-principles calculations have been employed to examine the possible use of electron energy loss spectroscopy (EELS) as a tool for determining the presence of OH groups and hence hydrogen content in compounds. Our density functional theory (DFT) based calculations describe accurately the experimental EELS results for forsterite (Mg2SiO4), hambergite (Be2BO3(OH)), brucite (Mg(OH)2) and diaspore (α-AlOOH). DFT calculations were complemented by an experimental time resolved study of the oxygen K-edge in diaspore. The results show unambiguously that there is no connection between a pre-edge feature in the oxygen K-edge spectrum of diaspore and the presence of OH groups in the structure. Instead, the experimental study shows that the pre-edge feature in diaspore is transient. It can be explained by the presence of molecular O2, which is produced as a result of the electron irradiation.

Physical review / B 94(13), 134109 (2016). doi:10.1103/PhysRevB.94.134109, The pressure-induced phase transition of monazite-type LaPO$_{4}$ at ≈26 GPa is studied by single-crystal x-ray diffraction and second harmonic generation (SHG) up to 31 GPa. The structure of the postmonazite phase of LaPO$_{4}$ has been obtained and it is shown that it corresponds to a post-barite-type structure with an acentric space group P2$_1$2$_1$2$_1$. A strong increase of the SHG signal at the transition confirms that the high-pressure polymorph is noncentrosymmetric. The phase transition involves a significant discontinuous decrease of the unit-cell volume by 6%, which is mainly due to a strong contraction of the a lattice parameter. Enthalpy differences between polymorphs with monazite-, barite-, and post-barite-type structures have been obtained from density-functional-theory-based calculations. They also yield a transition pressure of 21 GPa for the monazite to postbarite phase transition, but indicate that the barite-type phase is significantly more stable, implying that the transition into this phase may be kinetically hindered. As the transition pressure for the monazite-type to post-barite-type structure is reproduced with reasonable accuracy, we predict the corresponding phase-transition pressures of NdPO$_{4}$ and GdPO$_{4}$ to be 35 and 45 GPa, respectively., Published by Inst., Woodbury, NY

We report on a nine-month-old girl who presented with persisting cough, and diminished ventilation of the left hemithorax. Viral pneumonia was suspected after Adenovirus detection by PCR, but chest X-rays showed a persistent shadowing of the left hemithorax and persistent coughing despite clinical improvement. Because of the discrepancy between clinical and radiological signs further investigations by ultrasound and CT scan were performed, which visualized an intrathroracic tumor. Histopathology confirmed diagnosis of a teratoma. This case highlights the need for careful evaluation by the treating physicians. If the chest X-ray provides a discrepancy to the clinical findings or persistent pathologies exist, differential diagnosis should be discussed and further diagnostics be performed.

To spur energy security for sustainable rural development the “Integrated Renewable Energy Potential Assessment” (IREPA) was developed to explore the implementation potential of renewable resources considering the role of energy in diverse rural livelihoods. IREPA was applied in a case study in rural South Africa. Based on a participatory and holistic household and community assessment (i) currently un-utilized bioenergy resources, including animal manures, human faeces, organic wastes and grassland biomass, were assessed; (ii) social, environmental and techno­economic sustainability criteria (social cohesion, food and water security, gender aspects -protection of soil, water and air -operation and maintenance, investment costs) and available construction material were identified; and (iii) appropriate bioenergy technologies were selected with the Analytical Hierarchy Process. A simple plastic plug flow biodigester is considered the most appropriate bioenergy technology resulting in an implementation potential of 942 MWh per year on community level (or 3.5 kWh useable energy per household and day). The holistic and participatory bottom-up IREPA approach encourages the implementation of existing bioenergy potentials to spur access to clean and modern energy in rural areas of developing and emerging economies., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 273-281