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S G Dolley, G F Steyn, T J van Rooyen, F Szelecsényi, Z Kovács, C Vermeulen, N P van der Meulen
A method is described to determine the activity of non-pure positron emitters in a radionuclide production environment by assessing the 511keV annihilation radiation concurrently with selected γ-lines, using a single High-Purity Germanium (HPGe) detector. Liquid sources of (22)Na, (52)Fe, (52m)Mn, (61)Cu, (64)Cu, (65)Zn, (66)Ga, (68)Ga, (82)Rb, (88)Y, (89)Zr and (132)Cs were prepared specifically for this study. Acrylic absorbers surrounding the sources ensured that the emitted β(+)-particles could not escape and annihilate away from the source region...
August 1, 2017: Applied Radiation and Isotopes
Yunxia Gao, Ying Yang, Wenjun Zheng, Yuanyuan Su, Xiang Zhang, Herbert W Roesky
Germanium and tin monoxides (MO, M = Ge, Sn) were trapped by the 1,2,4-diazaphospholide-based germylene and stannylene M[3,5-tBu2dp]2 (M = Ge (2), Sn (3)), resulting in the Lewis acid-base adduct of composition M(μ-O)[M{η(1)(N)-(3,5-tBu2dp)}2]2 (M = Ge (4), Sn (5)). Compounds 4 and 5 were characterized by single-crystal X-ray structural analysis. The bonding features of 4 and 5 were supported by DFT calculations.
August 16, 2017: Inorganic Chemistry
Fengping Li, Wei Wei, Xingshuai Lv, Baibiao Huang, Ying Dai
The structural and electronic properties of germanene are always strongly modulated by the hybridization effects with metal substrates. In order to see what will happen when a buffer layer is introduced in-between germanene and metal substrates, we study the structural and electronic properties of the recently synthesized monolayer and bilayer germanene on Cu(111) though first-principles calculations. Our results show that the monolayer germanene on Cu(111) displays a nearly flat configuration and interface states form between the Ge pz and Cu sp-like states, with the Ge π states maintaining the Dirac character...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Dezhi Tan, Wenjin Zhang, Xiaofan Wang, Sandhaya Koirala, Yuhei Miyauchi, Kazunari Matsuda
Layered materials, such as graphene, transition metal dichalcogenides and black phosphorene, have been established rapidly as intriguing building blocks for optoelectronic devices. Here, we introduce highly polarization sensitive, broadband, and high-temperature-operation photodetectors based on multilayer germanium sulfide (GeS). The GeS photodetector shows a high photoresponsivity of about 6.8 × 10(3) A W(-1), an extremely high specific detectivity of 5.6 × 10(14) Jones, and broad spectral response in the wavelength range of 300-800 nm...
August 15, 2017: Nanoscale
Thaer M Dieb, Shenghong Ju, Kazuki Yoshizoe, Zhufeng Hou, Junichiro Shiomi, Koji Tsuda
Complex materials design is often represented as a black-box combinatorial optimization problem. In this paper, we present a novel python library called MDTS (Materials Design using Tree Search). Our algorithm employs a Monte Carlo tree search approach, which has shown exceptional performance in computer Go game. Unlike evolutionary algorithms that require user intervention to set parameters appropriately, MDTS has no tuning parameters and works autonomously in various problems. In comparison to a Bayesian optimization package, our algorithm showed competitive search efficiency and superior scalability...
2017: Science and Technology of Advanced Materials
Masaki Shimizu, Daiki Ryuse, Takumi Kinoshita
[1]Benzogermolo[3,2-b]indoles, [1]benzogermolo[3,2-b]-benzofuran, [1]benzogermolo[3,2-b]benzothiophene, and [1]benzo-germolo[3,2-b]benzothiophene-S,S-dioxide were synthesized from the corresponding 3-bromo-2-(2-bromophenyl)benzoheteroles and characterized. A comparison of the absorption spectra of the Ph2Ge- and Ph2Si-bridged 2-phenylindoles reveals that the Ge-bridge has the effect of slightly widening the HOMO-LUMO energy gap of the bridged 2-phenylindole π-system with regard to the Si-bridged system. Replacement of the indole ring by benzofuran or benzothiophene rings induces blue-shifts in the absorption spectrum, while the absorption spectrum of the benzothiophene-S,S-dioxide derivative was red-shifted with respect to the indole derivative...
August 11, 2017: Chemistry: a European Journal
Debdas Dhabal, Charusita Chakravarty, Valeria Molinero, Hemant K Kashyap
We use molecular dynamics simulations to compare and contrast the liquid-state anomalies in the Stillinger-Weber models of monatomic water (mW), silicon (Si), and germanium (Ge) over a fairly wide range of temperatures and densities. The relationships between structure, entropy, and mobility, as well as the extent of the regions of anomalous behavior, are discussed as a function of the degree of tetrahedrality. We map out the cascade of density, structural, pair entropy, excess entropy, viscosity, and diffusivity anomalies for these three liquids...
December 7, 2016: Journal of Chemical Physics
Shingo Kobayashi, Takayuki Shinomiya, Takahiro Ishikawa, Hitoshi Imaseki, Kazuki Iwaoka, Hisashi Kitamura, Satoshi Kodaira, Keisuke Kobayashi, Masakazu Oikawa, Norihiro Miyaushiro, Yoshio Takashima, Yukio Uchihori
A low (134)Cs/(137)Cs ratio anomaly in the north-northwest (NNW) direction from the Fukushima Dai-ichi Nuclear Power Station (FDNPS) is identified by a new analysis of the (134)Cs/(137)Cs ratio dataset which we had obtained in 2011-2015 by a series of car-borne surveys that employed a germanium gamma-ray spectrometer. We found that the (134)Cs/(137)Cs ratio is slightly lower (0.95, decay-corrected to March 11, 2011) in an area with a length of about 15 km and a width of about 3 km in the NNW direction from the FDNPS than in other directions from the station...
August 7, 2017: Journal of Environmental Radioactivity
Lada Vukušić, Josip Kukučka, Hannes Watzinger, Georgios Katsaros
Heavy holes confined in quantum dots are predicted to be promising candidates for the realization of spin qubits with long coherence times. Here we focus on such heavy-hole states confined in Germanium hut wires. By tuning the growth density of the latter we can realize a T-like structure between two neighboring wires. Such a structure allows the realization of a charge sensor, which is electrostatically and tunnel coupled to a quantum dot, with charge-transfer signals as high as 0.3 e. By integrating the T-like structure into a radio-frequency reflectometry setup, single-shot measurements allowing the extraction of hole tunneling times are performed...
August 10, 2017: Nano Letters
Blaž Alič, Melita Tramšek, Anton Kokalj, Gašper Tavčar
The recently prepared novel naked fluoride reagent 1,3-bis(2,6-diisopropylphenyl)imidazolium fluoride ([(L(Dipp))H][F]), treated with an excess of MF4 (M = Si, Ge), results in isolation of [(L(Dipp))H][MF5] products with the elusive trigonal bipyramidal MF5(-) anions. Specific steric characteristics of the [(L(Dipp))H](+) cation readily support isolation of monomeric and discrete trigonal bipyramidal fluorido anions of silicon and germanium. Based on combination of experimental results and DFT calculations, we demonstrate that the role of bulky cation is not solely due to steric hindering but also due to electrostatic effects, which are important in the design of such uncommon species...
August 9, 2017: Inorganic Chemistry
L Pibida, B Zimmerman, D E Bergeron, R Fitzgerald, J T Cessna, L King
The National Institute of Standards and Technology (NIST) performed new standardization measurements for (64)Cu. As part of this work the photon emission probability for the main gamma-ray line and the half-life were determined using several high-purity germanium (HPGe) detectors. Half-life determinations were also carried out with a NaI(Tl) well counter and two pressurized ionization chambers.
July 4, 2017: Applied Radiation and Isotopes
Ibtihel Chaabane, Debika Banerjee, Oualid Touayar, Sylvain G Cloutier
Due to its high refractive index, reflectance is often a problem when using Germanium for optoelectronic devices integration. In this work, we propose an effective and low-cost nano-texturing method for considerably reducing the reflectance of bulk Germanium. To do so, uniform V-shape pit arrays are produced by wet electroless chemical etching in a 3:1 volume ratio of highly-concentrated hydrochloridric and nitric acids or so-called aqua regia bath using immersion times ranging from 5 to 60 min. The resulting pit morphology, the crystalline structure of the surface and the changes in surface chemistry after nano-patterning are all investigated...
July 26, 2017: Materials
Manuel Radek, Bartosz Liedke, Bernd Schmidt, Matthias Voelskow, Lothar Bischoff, John Lundsgaard Hansen, Arne Nylandsted Larsen, Dominique Bougeard, Roman Böttger, Slawomir Prucnal, Matthias Posselt, Hartmut Bracht
Crystalline and preamorphized isotope multilayers are utilized to investigate the dependence of ion beam mixing in silicon (Si), germanium (Ge), and silicon germanium (SiGe) on the atomic structure of the sample, temperature, ion flux, and electrical doping by the implanted ions. The magnitude of mixing is determined by secondary ion mass spectrometry. Rutherford backscattering spectrometry in channeling geometry, Raman spectroscopy, and transmission electron microscopy provide information about the structural state after ion irradiation...
July 17, 2017: Materials
Muazzez Çelik Karakaya, Mahmut Doğru, Necati Karakaya, Fatih Kuluöztürk, Mahmut Tahir Nalbantçılar
The study aims to determine the radioactivity levels of thermal waters which have been used seasonally or permanently in spas for therapeutic intentions. Samples were collected from spas in different regions of Turkey. Some radionuclides ((40)K, (232)Th, (226)Ra, (137)Cs), gross alpha (GA) and gross beta (GB) activities, and physical and some chemical parameters were measured. Gamma radiation measurements for (226)Ra, (232)Th and (40)K radionuclides were performed by using a high purity germanium (HPGe) detector...
August 2017: Journal of Water and Health
Siwei Tang, Ivan Kravchenko, T Z Ward, Qiang Zou, Jieyu Yi, Cheng Ma, Miaofang Chi, Guixin Cao, An-Ping Li, David Mandrus, Zheng Gai
We report the synthesis of single-crystal iron germanium nanowires via chemical vapor deposition without the assistance of any catalysts. The assembly of single-crystal FeGe2 nanowires with tetragonal C16 crystal structure shows anisotropic magnetic behavior along the radial direction or the growth axial direction, with both antiferromagnetic and ferromagnetic orders. Single FeGe2 nanowire devices were fabricated using e-beam lithography. Electronic transport measurement in these devices show two resistivity anomalies near 250 K and 200 K which are likely signatures of the two spin density wave states in FeGe2...
August 2, 2017: Scientific Reports
Sho Iwagami, Yuichi Onda, Maki Tsujimura, Manami Hada, Ishwar Pun
Radiocesium ((137)Cs) migration from headwater forested areas to downstream rivers has been investigated in many studies since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, which was triggered by a catastrophic earthquake and tsunami on 11 March 2011. The accident resulted in the release of a huge amount of radioactivity and its subsequent deposition in the environment. A large part of the radiocesium released has been shown to remain in the forest. The dissolved (137)Cs concentration and its temporal dynamics in river water, stream water, and groundwater have been reported, but reports of dissolved (137)Cs concentration in soil water remain sparse...
July 28, 2017: Environmental Pollution
Oleksandr Kysliak, Claudio Schrenk, Andreas Schnepf
The reaction of [(Hyp)2Ge9](2-) (Hyp = Si(SiMe3)3) with ClSiMe2-C6H4-SiMe2Cl gives [K(THF)][(Hyp)2Ge9-SiMe2-C6H4-SiMe2-Ge9(Hyp)2K] K1 in 45% yield in the form of orange-red crystals. 1 is thereby the first compound where two Ge9(Hyp)2 clusters are bound together via a bridging ligand. 1 is stable in solution but cannot be transferred intact into the gas phase via electrospray ionization indicating a higher reactivity with respect to other metalloid Ge9R3 clusters. The arrangement of the nine germanium atoms within the two Ge9 units in 1 is unique for metalloid Ge9R3 clusters...
August 1, 2017: Inorganic Chemistry
Andrew C Serino, Jesse S Ko, Michael T Yeung, Jeffrey J Schwartz, Chris B Kang, Sarah H Tolbert, Richard B Kaner, Bruce S Dunn, Paul S Weiss
The high theoretical energy density of alloyed lithium and germanium (Li15Ge4), 1384 mAh/g, makes germanium a promising anode material for lithium-ion batteries. However, common alloy anode architectures suffer from long-term instability upon repetitive charge-discharge cycles that arise from stress-induced degradation upon lithiation (volume expansion >300%). Here, we explore the use of the two-dimensional nanosheet structure of germanane to mitigate stress from high volume expansion and present a facile method for producing stable single-to-multisheet dispersions of pure germanane...
August 7, 2017: ACS Nano
Zhongyunshen Zhu, Yuxin Song, Qimiao Chen, Zhenpu Zhang, Liyao Zhang, Yaoyao Li, Shumin Wang
We theoretically investigate highly tensile-strained Ge nanowires laterally on GaSb. Finite element method has been used to simulate the residual elastic strain in the Ge nanowire. The total energy increment including strain energy, surface energy, and edge energy before and after Ge deposition is calculated in different situations. The result indicates that the Ge nanowire on GaSb is apt to grow along 〈100〉 rather than 〈110〉 in the two situations and prefers to be exposed by {105} facets when deposited a small amount of Ge but to be exposed by {110} when the amount of Ge exceeds a critical value...
December 2017: Nanoscale Research Letters
Amy Christine Brown
BACKGROUND: No tabular summary of potentially life-threatening, kidney-toxic dietary supplements (DS; includes herbs) based on PubMed case reports is currently available online and continually updated to forewarn United States consumers, clinicians, and companies manufacturing DS. The purpose of this review was to create an online research summary table of kidney toxicity case reports related to DS. METHODS: Documented PubMed case reports (1966 to May 2016, and cross-referencing) of DS appearing to contribute to kidney toxicity were listed in "DS Toxic Tables...
September 2017: Food and Chemical Toxicology
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