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Isao Komiya, Yoshiyuki Umezu, Toshioh Fujibuchi, Kazumasa Nakamura, Shingo Baba, Hiroshi Honda
The non-self-shield compact medical cyclotron and the cyclotron vault room were in operation for 27 years. They have now been decommissioned. We efficiently implemented a technique to identify an activation product in the cyclotron vault room. Firstly, the distribution of radioactive concentrations in the concrete of the cyclotron vault room was estimated by calculation from the record of the cyclotron operation. Secondly, the comparison of calculated results with an actual measurement was performed using a NaI scintillation survey meter and a high-purity germanium detector...
2016: Nihon Hoshasen Gijutsu Gakkai Zasshi
Theresia Ahrens, Michael Teltewskoi, Mike Ahrens, Thomas Braun, Reik Laubenstein
The reaction of the silyl complex [Rh{Si(OEt)3}(PEt3)3] (1) with 3,3,3-trifluoropropene afforded the rhodium complex [Rh(CH2CHCF3){Si(OEt)3}(PEt3)2] (2) which features a bonded fluorinated olefin. In contrast the rhodium hydrido complex [Rh(H)(PEt3)3] (3) yielded on treatment with 3,3,3-trifluoropropene in the presence of a base the fluorido complex [Rh(F)(PEt3)3] (4) together with 1,1-difluoro-1-propene by C-F bond activation. At low temperature the intermediate fac-[Rh(H)(CH2CHCF3)(PEt3)3] (5) was detected by NMR spectroscopy...
October 14, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Davide Colleoni, Alfredo Pasquarello
The minimum-energy paths for the diffusion of an interstitial O atom in silicon and germanium are studied through the nudged-elastic-band method and hybrid functional calculations. The reconsideration of the diffusion of O in silicon primarily serves the purpose of validating the procedure for studying the O diffusion in germanium. Our calculations show that the minimum energy path goes through an asymmetric transition state in both silicon and germanium. The stability of these transition states is found to be enhanced by the generation of unpaired electrons in the highest occupied single-particle states...
October 12, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Simantini Nayak, Andreas Erbe
In acidic solution, germanium surfaces undergo a transformation to hydrogen-terminated surfaces at sufficiently negative electrode potentials. Herein, we used in situ and operando attenuated total reflection infrared (ATR-IR) spectroscopy coupled to electrochemical experiments to study the details of this surface transformation on Ge(111) and Ge(100) in 0.1 M HClO4. The ATR-IR data gathered during the surface transformation are consistent with an interpretation according to which an intermediate state exists of a surface with mixed termination...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
Yung-Chen Lin, Ismail Bilgin, Towfiq Ahmed, Renjie Chen, Doug Pete, Swastik Kar, Jian-Xin Zhu, Gautam Gupta, Aditya Mohite, Jinkyoung Yoo
Heterostructuring provides novel opportunities for exploring emergent phenomena and applications by developing designed properties beyond those of homogeneous materials. Advances in nanoscience enable the preparation of heterostructures formed incommensurate materials. Two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides, are of particular interest due to their distinct physical characteristics. Recently, 2D/2D heterostructures have opened up new research areas. However, other heterostructures such as 2D/three-dimensional (3D) materials have not been thoroughly studied yet although the growth of 3D materials on 2D materials creating 2D/3D heterostructures with exceptional carrier transport properties has been reported...
October 6, 2016: Nanoscale
Manish Gupta, Abhinav Kranti
In this work, we examine the feasibility of triggering impact ionisation at sub-bandgap voltages through optimal utilisation of structural non-ideality induced electric field redistribution in the semiconductor film for an energy efficient steep switching junctionless (JL) transistor. While misalignment between front and back gates is often considered as a disadvantage due to loss of gate controllability, the work highlights its usefulness and applicability in nanoscale devices to engineer the electric field to enhance the product of current density (J) and electric field (E) and activate impact ionisation at sub-bandgap applied voltages...
November 11, 2016: Nanotechnology
Harekrishna Ghosh, Ahmed Bouhekka, Thomas Bürgi
Germanium-polyelectrolyte-gold nanoparticle composites were prepared and characterized using FTIR-ATR spectroscopy and scanning electron microscopy. The germanium (Ge) element served as an internal reflection element and the buildup of the layered system was followed in situ. A positively charged polyelectrolyte, poly (allylamine hydrochloride) (PAH) adsorbs spontaneously on negatively charged Ge. Citrate-stabilized gold nanoparticles can then be adsorbed onto the PAH layer. Upon illumination of the device with visible light a prominent absorption over the entire mid infrared region is observed which is due to intervalence band transitions in Ge...
September 29, 2016: Physical Chemistry Chemical Physics: PCCP
Duck Hyun Youn, Nicholas A Patterson, Hunmin Park, Adam Heller, C Buddie Mullins
The simple fabrication of composites of germanium nanoparticles dispersed on nitrogen-doped carbon nanospheres (Ge/NC) of varying nitrogen content and their performance in lithium ion battery anodes are reported. A heavily nitrogen-doped carbon gel was formed by condensing m-phenylenediamine with formaldehyde (PF-gel); a less heavily N-doped gel was formed by condensing resorcinol and m-phenylenediamine with formaldehyde (RPF-gel); and an undoped gel was formed by condensing resorcinol with formaldehyde (RF-gel)...
October 6, 2016: ACS Applied Materials & Interfaces
Akihiko Nakatsuka, Kazumasa Sugiyama, Makio Ohkawa, Osamu Ohtaka, Keiko Fujiwara, Akira Yoshiasa
The Sr-Ge-O system has an earth-scientific importance as a potentially good low-pressure analog of the Ca-Si-O system, one of the major components in the constituent minerals of the Earth's crust and mantle. However, it is one of the germanate systems that has not yet been fully examined in the phase relations and structural properties. The recent findings that the SrGeO3 high-pressure perovskite phase is the first Ge-based transparent electronic conductor make the Sr-Ge-O system interesting in the field of materials science...
October 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
David Nieder, Volker Huch, Cem B Yildiz, David Scheschkewitz
An isolable NHC-coordinated disilenyl germylene R2Si═SiR-GePh·NHC(iPr2)(Me2) (5b: R = 2,4,6-triisopropylphenyl, NHC(iPr2)(Me2) = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) is obtained from the reaction of the α-chloro silyl functionalized heavier vinylidene analogue R2(Cl)Si-RSi═Ge·NHC(iPr2)(Me2) with phenyllithium. The disilenyl germylene 5b isomerizes at 40 °C to the NHC-adduct of the corresponding heavier cyclopropylidene analogue 6b. Both 5b and 6b display near perfect regiodiscrimination in their reactions with phenylacetylene and xylyl isocyanide, affording in the case of each reagent two different regioisomers of NHC-coordinated cyclic germylenes...
October 14, 2016: Journal of the American Chemical Society
Lichuan Jin, Dainan Zhang, Huaiwu Zhang, Jue Fang, Yulong Liao, Tingchuan Zhou, Cheng Liu, Zhiyong Zhong, Vincent G Harris
Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10-180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400-1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%...
September 26, 2016: Scientific Reports
Haiping Jia, Richard Kloepsch, Xin He, Marco Evertz, Sascha Nowak, Jie Li, Martin Winter, Tobias Placke
In this work, a ZnFe2O4 anode material was successfully synthesized by a novel ionic liquid-assisted synthesis method followed by a carbon coating procedure. The as-prepared ZnFe2O4 particles demonstrate a relatively homogeneous particle size distribution with particle diameters ranging from 40 to 80 nm. This material, which is well known to offer an interesting combination of an alloying and conversion mechanism, is capable of accommodating nine equivalents of lithium per unit formula, resulting in a high specific capacity (≥ 1,000 mAh g-1)...
2016: Acta Chimica Slovenica
Carlos Alonso-Ramos, Milos Nedeljkovic, Daniel Benedikovic, Jordi Soler Penadés, Callum G Littlejohns, Ali Z Khokhar, Diego Pérez-Galacho, Laurent Vivien, Pavel Cheben, Goran Z Mashanovich
A broad transparency range of its constituent materials and compatibility with standard fabrication processes make germanium-on-silicon (Ge-on-Si) an excellent platform for the realization of mid-infrared photonic circuits. However, the comparatively large Ge waveguide thickness and its moderate refractive index contrast with the Si substrate hinder the implementation of efficient fiber-chip grating couplers. We report for the first time, to the best of our knowledge, a single-etch Ge-on-Si grating coupler with an inversely tapered access stage, operating at a 3...
September 15, 2016: Optics Letters
Francesco De Leonardis, Benedetto Troia, Richard A Soref, Vittorio M N Passaro
Silicon (Si), tin (Sn), and germanium (Ge) alloys have attracted research attention as direct band gap semiconductors with applications in electronics and optoelectronics. In particular, GeSn field effect transistors can exhibit very high performance in terms of power reduction and operating speed because of the high electron drift mobility, while the SiGeSn system can be constructed using CMOS-compatible techniques to realize lasers, LED, and photodetectors. The wide Si, Ge and Sn transparencies allow the use of binary and ternary alloys extended to mid-IR wavelengths, where nonlinearities can also be employed...
2016: Scientific Reports
Ruining Wang, Davide Campi, Marco Bernasconi, Jamo Momand, Bart J Kooi, Marcel A Verheijen, Matthias Wuttig, Raffaella Calarco
Using reflection high-energy electron diffraction (RHEED), the growth onset of molecular beam epitaxy (MBE) deposited germanium telluride (GeTe) film on Si(111)-(√3 × √3)R30°-Sb surfaces is investigated, and a larger than expected in-plane lattice spacing is observed during the deposition of the first two molecular layers. High-resolution transmission electron microscopy (HRTEM) confirms that the growth proceeds via closed layers, and that those are stable after growth. The comparison of the experimental Raman spectra with theoretical calculated ones allows assessing the shift of the phonon modes for a quasi-free-standing ultra-thin GeTe layer with larger in-plane lattice spacing...
2016: Scientific Reports
R Alaee, M Albooyeh, S Tretyakov, C Rockstuhl
We suggest a novel switchable plasmonic dipole nanoantenna operating at mid-infrared frequencies that exploits phase-change materials. We show that the induced dipole moments of a nanoantenna, where a germanium antimony telluride (Ge<sub>3</sub>Sb<sub>2</sub>Te<sub>6</sub> or GST for short) nanopatch acts as a spacer between two coupled metallic nanopatches, can be controlled in a disruptive sense. By switching GST between its crystalline and amorphous phases, the nanoantenna can exhibit either an electric or a balanced magneto-electric dipole-like radiation...
September 1, 2016: Optics Letters
Lingen Zhang, Zhenming Xu
Germanium, as strategic reserve metal, plays critical role in high-tech industry. However, a contradiction of increasing consumption and scarcity of germanium resource is becoming more and more prominent. This paper proposed an integrated process to recycle germanium from coal fly ash. This technological process mainly consisted of two procedures: vacuum reduction with the purposes of enriching germanium and chlorinated distillation with the purposes of purifying germanium. Several highlights are summarized as follows: (i) Separation principle and reaction mechanism were discussed to understand this integrated process...
August 30, 2016: Journal of Hazardous Materials
Kazuhiro Fuchizaki, Takahiro Sakagami, Shinji Kohara, Akitoshi Mizuno, Yuta Asano, Nozomu Hamaya
A molecular liquid GeI4 is a candidate that undergoes a pressure-induced liquid-to-liquid phase transition. This study establishes the reference structure of the low-pressure liquid phase. Synchrotron x-ray diffraction measurements were carried out at several temperatures between the melting and the boiling points under ambient pressure. The molecule has regular tetrahedral symmetry, and the intramolecular Ge-I length of 2.51 Å is almost temperature-independent within the measured range. A reverse Monte Carlo (RMC) analysis is employed to find that the distribution of molecular centers remains self-similar against heating, and thus justifying the length-scaling method adopted in determining the density...
November 9, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Dongdong Li, Pengfei Li, Bingyan Qu, B C Pan, B Zhang, H Y He, Rulong Zhou
A global search for the stable structures of bilayer Ge (BLG) is performed, and the most stable and meta-stable BLG structures are predicted for the first time. Phonon-spectrum calculations and ab initio molecular dynamics simulations confirm their dynamical and thermal stability. The computed electronic structures suggest that the most stable structure is metal while the meta-stable structure of BLG is a semiconductor with an indirect band gap (0.32 eV at the level of PBE functional and 0.81 eV at the level of HSE06)...
September 28, 2016: Nanoscale
O Aviv, H B Spitz, H Datz, G Haquin, Y Shamai, E Daniely, Z Yungrais, J Koch
The performance characteristics of a shadow-shield whole-body counter system with an array of four high-resolution germanium detectors using whole-body and organ-specific (lungs, liver, head, knee and thyroid) physical phantoms are described. Detection efficiency and minimum detectable activities for selected radionuclides and several measurement configurations are presented. Results demonstrate that the system meets the requirements for direct radio bioassay and that detection efficiency and minimum detectable activities are similar in magnitude to other whole-body (or organ) counting systems installed in fully shielded structures...
September 2, 2016: Radiation Protection Dosimetry
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