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Henry Auer, Holger Kohlmann
The hydrogenation of Zintl phases enables the formation of new structural entities with main group element-hydrogen bonds in the solid state. The hydrogenation of SrSi, BaSi and BaGe yields the hydrides SrSiH5/3-x, BaSiH5/3-x and BaGeH5/3-x, whose crystal structures were solved by a combination of X-ray, neutron and electron diffraction. Layers of connected HSr4 (HBa4) tetrahedra containing hydride ions alternate with layers of infinite single- and double-chain polyanions, where hydrogen atoms are covalently bound to silicon and germanium...
July 20, 2017: Angewandte Chemie
Shenglai Yao, Yun Xiong, Matthias Driess
Monoatomic zerovalent main-group element complexes emerged very recently and attracted increasing attention of both theoretical and experimental chemists. In particular, zerovalent silicon complexes and their congeners (metallylones) stabilized by neutral Lewis donors are of significant importance not only because of their intriguing electronic structure but also because they can serve as useful building blocks for novel chemical species. Featuring four valence electrons as two lone pairs at the central atoms, such complexes may form donor-acceptor adducts with Lewis acids...
July 19, 2017: Accounts of Chemical Research
Xiaojun Li, Shuna Li, Hongjiang Ren, Juxiang Yang, Yongqiang Tang
A new series of alkali-based complexes, AM@GenAu (AM = Li, Na, and K), have been theoretically designed and investigated by means of the density functional theory calculations. The geometric structures and electronic properties of the species are systematically analyzed. The adsorption of alkali metals maintains the structural framework of the gold-germanium bimetallic clusters, and the alkali metals prefer energetically to be attached on clusters' surfaces or edges. The high chemical stability of Li@Ge12Au is revealed by the spherical aromaticity, the hybridization between the Ge atoms and Au-4d states, and delocalized multi-center bonds, as well as large binding energies...
July 17, 2017: Nanomaterials
Jonas M C Nilsson, Robert R Finck, Christopher L Rääf
For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built...
July 13, 2017: Journal of Environmental Radioactivity
Chih-Hsien Lai, Guo-An Wang, Tsung-Kai Ling, Tzyy-Jiann Wang, Po-Kai Chiu, Yuan-Fong Chou Chau, Chih-Ching Huang, Hai-Pang Chiang
It is desirable to extend the surface-enhanced Raman scattering (SERS) from the conventionally used visible range into the infrared region, because the fluorescence background is lower in the long-wavelength regime. To do this, it is important to have a SERS substrate suitable for infrared operation. In this work, we report the near infrared SERS operation based on the substrates employing star-shaped gold/silver nanoparticles and hyperbolic metamaterial (HMM) structure. We first fabricate the SERS substrate in which nanoparticles are separated from a silver film by a thin dielectric layer...
July 14, 2017: Scientific Reports
Luba Hunakova, Julius Brtko
Among a variety of metal containing organic compounds, tin derivatives are enjoying an increasing interest and appear to be very promising as potential drug candidates. We studied eight organometallic derivatives, nuclear retinoid X receptor (RXR) ligands and two germanium containing derivates that do not serve as RXR ligands. Tributylgermanium chloride (TBGe) and triphenylgermanium chloride (TPGe) did not inhibit growth of human triple negative MDA-MB-231 breast cancer cells. On the other hand, the tributyltin derivatives were highly, the triphenyltin derivatives less cytotoxic, both groups with IC50 values of nanomolar range...
July 11, 2017: Toxicology Letters
Arun Upmanyu, Gurjot Singh, Heena Duggal, H S Kainth, Atul Bhalla, Sanjeev Kumar
The present work reports Rayleigh scattering cross section measurements for the 39.5keV (Sm- Kα2), 40.1keV (Sm-Kα1) and 45.4keV (Sm-Kβ1,3) X-ray photons in 35 elements with 26 ≤ Z ≤ 83 at backward angle of 139°. The scattering measurements were performed in reflection mode geometrical set up involving a secondary photon source consisting of Samarium (62Sm) target excited by the 59.54keV γ-rays from the (241)Am radioactive source. The scattered photons were detected using a low energy germanium (LEGe) detector...
July 8, 2017: Applied Radiation and Isotopes
Masahiro Kako, Shigeru Nagase, Takeshi Akasaka
Exohedral derivatization of endohedral metallofullerenes (EMFs) has been exploited as a useful method for characterizing the structural and chemical properties of EMFs, and for functionalizing them for potential applications. The introduction of heteroatoms, such as electropositive silicon atoms, to fullerene cages is a novel functionalization method that remarkably affects the electronic characteristics of fullerenes. This review comprehensively describes the results of the reactions of monometallofullerene, dimetallofullerene, and trimetallic nitride template EMFs with disilirane, silirane, silylene, and digermirane, which afforded the corresponding silylated and germylated fullerenes...
July 14, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Chi Xu, Nalin S Fernando, Stefan Zollner, John Kouvetakis, José Menéndez
Phase-filling singularities in the optical response function of highly doped (>10^{19}  cm^{-3}) germanium are theoretically predicted and experimentally confirmed using spectroscopic ellipsometry. Contrary to direct-gap semiconductors, which display the well-known Burstein-Moss phenomenology upon doping, the critical point in the joint density of electronic states associated with the partially filled conduction band in n-Ge corresponds to the so-called E_{1} and E_{1}+Δ_{1} transitions, which are two-dimensional in character...
June 30, 2017: Physical Review Letters
Dharmraj Kotekar-Patil, Binh-Minh Nguyen, Jinkyoung Yoo, Shadi A Dayeh, Sergey M Frolov
We study signatures of ballistic quantum transport of holes through Ge/Si core/shell nanowires at low temperatures. We observe Fabry-Perot interference patterns as well as conductance plateaus at integer multiples of 2e^2/h at zero magnetic field. Magnetic field evolution of these plateaus reveals relatively large effective Lande g-factors. Ballistic effects are observed in nanowires with silicon shell thicknesses of 1 - 3 nm, but not in bare germanium wires. These findings inform the future development of spin and topological quantum devices which rely on ballistic subband-resolved transport...
July 13, 2017: Nanotechnology
Yuan Tu, Bin Han, Yasuo Shimizu, Koji Inoue, Yuiko Fukui, Maasa Yano, Takashi Tanii, Takahiro Shinada, Yasuyoshi Nagai
Ion implantation through nanometer-scale apertures (nano-apertures) is a promising method to precisely position ions in silicon matrices, which is a requirement for next generation electronic and quantum computing devices. This paper reports the first-ever use of atom probe tomography (APT) to investigate the three-dimensional distribution of germanium atoms in silicon after implantation through nano-aperture of 10 nm in diameter, for evaluation of the amount and spatial distribution of implanted dopants. The experimental results obtained by APT are consistent with a simple simulation with consideration to several effects during lithography and ion implantation, such as channeling and resist flow...
July 12, 2017: Nanotechnology
M-C Lépy, L Brondeau, Y Ménesguen, S Pierre, J Riffaud
The efficiency calibration for different high-purity germanium detectors in the low-energy range was established by the conventional method, using standard radioactive sources. The peak shapes were carefully analysed taking account of natural linewidth, full-energy width at half maximum and scattering. Complementary information was obtained by Monte Carlo simulation using the PENELOPE code, after optimization of the geometrical parameters. This was used to measure photon emission intensities of some low-energy emitting radionuclides, including (133)Ba, and compared to the tabulated values...
July 5, 2017: Applied Radiation and Isotopes
Maritina Rouchota, Maria Georgiou, Eleftherios Fysikopoulos, Eirini Fragogeorgi, Konstantinos Mikropoulos, Panagiotis Papadimitroulas, George Kagadis, George Loudos
OBJECTIVE: To present a prototype tri-modal imaging system, consisting of a single photon emission computed tomography (SPET), a positron emission tomography (PET), and a computed tomography (CT) subsystem, evaluated in planar mode. MATERIALS AND METHODS: The subsystems are mounted on a rotating gantry, so as to be able to allow tomographic imaging in the future. The system, designed and constructed by our group, allows whole body mouse imaging of competent performance and is currently, to the best of our knowledge, unequaled in a national and regional level...
July 12, 2017: Hellenic Journal of Nuclear Medicine
Zhenyang Xia, Haomin Song, Munho Kim, Ming Zhou, Tzu-Hsuan Chang, Dong Liu, Xin Yin, Kanglin Xiong, Hongyi Mi, Xudong Wang, Fengnian Xia, Zongfu Yu, Zhenqiang Jack Ma, Qiaoqiang Gan
Miniaturization of optoelectronic devices offers tremendous performance gain. As the volume of photoactive material decreases, optoelectronic performance improves, including the operation speed, the signal-to-noise ratio, and the internal quantum efficiency. Over the past decades, researchers have managed to reduce the volume of photoactive materials in solar cells and photodetectors by orders of magnitude. However, two issues arise when one continues to thin down the photoactive layers to the nanometer scale (for example, <50 nm)...
July 2017: Science Advances
Esteban D Cantero, Lara M Solis, Yongfeng Tong, Javier D Fuhr, María Luz Martiarena, Oscar Grizzi, Esteban A Sánchez
We studied the growth of Ge layers on Au(111) under ultra-high vacuum conditions from the submonolayer regime up to a few layers with Scanning Tunneling Microscopy (STM), Direct Recoiling Spectroscopy (DRS) and Low Energy Electron Diffraction (LEED). Most STM images for the thicker layers are consistent with a commensurate 5 × 8 arrangement. The high surface sensitivity of TOF-DRS allows us to confirm the coexistence of Au and Ge atoms in the top layer for all stages of growth. An estimation of the Au to Ge ratio at the surface of the thick layer gives about 1 Au atom per 2 Ge ones...
July 7, 2017: Physical Chemistry Chemical Physics: PCCP
M Fortin-Deschênes, O Waller, T O Menteş, A Locatelli, S Mukherjee, F Genuzio, P L Levesque, A Hébert, R Martel, O Moutanabbir
The lack of large-area synthesis processes on substrates compatible with industry requirements has been one of the major hurdles facing the integration of 2D materials in mainstream technologies. This is particularly the case for the recently discovered monoelemental group V 2D materials which can only be produced by exfoliation or growth on exotic substrates. Herein, to overcome this limitation, we demonstrate a scalable method to synthesize antimonene on germanium substrates using solid-source molecular beam epitaxy...
July 11, 2017: Nano Letters
Basel A Khader, Sean A F Peel, Mark R Towler
Glass polyalkenoate cements (GPCs) have potential as bio-adhesives due to their ease of application, appropriate mechanical properties, radiopacity and chemical adhesion to bone. Aluminium (Al)-free GPCs have been discussed in the literature, but have proven difficult to balance injectability with mechanical integrity. For example, zinc-based, Al-free GPCs reported compressive strengths of 63 MPa, but set in under 2 min. Here, the authors design injectable GPCs (IGPCs) based on zinc-containing, Al-free silicate compositions containing GeO₂, substituted for ZnO at 3% increments through the series...
July 5, 2017: Journal of Functional Biomaterials
C Bobin, C Thiam, J Bouchard
In the framework of an international BIPM comparison (Bureau International des Poids et Mesures), the activity standardization of (68)Ge in a solution of (68)Ge/(68)Ga in equilibrium provided by NIST was carried out at LNHB. This exercise was organized to meet the growing interest in (68)Ga as a radiopharmaceutical in nuclear medicine services (e.g. as a surrogate of (18)F for PET imaging). Due to the volatility of germanium, the activity standardization of (68)Ge was investigated at LNHB by means of 4πβ-γ coincidence counting based on Cherenkov measurements...
June 29, 2017: Applied Radiation and Isotopes
Justyna Marganiec-Gałązka, Ole J Nähle, Karsten Kossert
Germanium-68 is an important radionuclide since it is used to generate its daughter (68)Ga which is frequently used for positron emission tomography (PET). In addition, (68)Ge/(68)Ga sources are often used as surrogates for short-lived PET isotopes when calibrating instruments. In this work, 4πβ(Č)-γ coincidence counting was used to determine the activity concentration of a (68)Ge/(68)Ga solution. The presented measurements were made by means of a new PTB-custom-built 4π(LS)β-γ coincidence counting system, where a liquid scintillation detector in the β channel can also be used as a Čerenkov counter, and a NaI(Tl) crystal detects annihilation radiation...
June 20, 2017: Applied Radiation and Isotopes
Scott C Coste, Bess Vlaisavljevich, Danna E Freedman
Precise modulation of the magnetic anisotropy of a transition-metal center would affect physical properties ranging from photoluminescence to magnetism. Over the past decade, exerting nuanced control over ligand fields enabled the incorporation of significant magnetic anisotropy in a number of mononuclear transition-metal complexes. An alternate approach to increasing spin-orbit coupling relies upon using heavy diamagnetic main-group elements as sources of magnetic anisotropy. Interacting first-row transition metals with main-group elements enables the transfer of magnetic anisotropy to the paramagnetic metal center without restricting coordination geometry...
July 17, 2017: Inorganic Chemistry
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