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https://www.readbyqxmd.com/read/27908040/modeling-and-design-of-two-dimensional-membrane-type-active-acoustic-metamaterials-with-tunable-anisotropic-density
#1
Ahmed Allam, Adel Elsabbagh, Wael Akl
A two-dimensional active acoustic metamaterial with controllable anisotropic density is introduced. The material consists of composite lead-lead zirconate titanate plates clamped to an aluminum structure with air as the background fluid. The effective anisotropic density of the material is controlled, independently for two orthogonal directions, by means of an external static electric voltage signal. The material is used in the construction of a reconfigurable waveguide capable of controlling the direction of the acoustic waves propagating through it...
November 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27898013/health-effects-due-to-radionuclides-content-of-solid-minerals-within-port-of-richards-bay-south-africa
#2
Felix B Masok, Paulus L Masiteng, Risimati D Mavunda, Peane P Maleka
This study assessed the radiological health hazards to various body organs of workers working within Transnet Precinct in Richards Bay in Kwazulu-Natal, South Africa due to radionuclide content of mineral ores often stored within the facility. Thirty samples were collected from five mineral ores (rock phosphate, rutile, zircon, coal and hematite) and analyzed for (238)U, (234)U, (226)Ra, (210)Pb, (235)U, (232)Th, (228)Ra, (228)Th and (40)K using delayed neutron activation analysis and low energy gamma spectroscopy...
November 25, 2016: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/27886050/design-of-fresnel-lens-type-multi-trapping-acoustic-tweezers
#3
You-Lin Tu, Shih-Jui Chen, Yean-Ren Hwang
In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers use an ultrasound beam produced by a lead zirconate titanate (PZT) transducer operating at 2.4 MHz and 100 Vpeak-to-peak in a water medium. The design of the Fresnel lens (zone plate) is based on air reflection, acoustic impedance matching, and the Fresnel half-wave band (FHWB) theory...
November 23, 2016: Sensors
https://www.readbyqxmd.com/read/27834910/influence-of-pzt-coating-thickness-and-electrical-pole-alignment-on-microresonator-properties
#4
Giedrius Janusas, Sigita Ponelyte, Alfredas Brunius, Asta Guobiene, Andrius Vilkauskas, Arvydas Palevicius
With increasing technical requirements in the design of microresonators, the development of new techniques for lightweight, simple, and inexpensive components becomes relevant. Lead zirconate titanate (PZT) is a powerful tool in the formation of these components, allowing a self-actuation or self-sensing capability. Different fabrication methods lead to the variation of the properties of the device itself. This research paper covers the fabrication of a novel PZT film and the investigations of its chemical, surface, and dynamic properties when film thickness is varied...
November 10, 2016: Sensors
https://www.readbyqxmd.com/read/27799558/warm-storage-for-arc-magmas
#5
Mélanie Barboni, Patrick Boehnke, Axel K Schmitt, T Mark Harrison, Phil Shane, Anne-Sophie Bouvier, Lukas Baumgartner
Felsic magmatic systems represent the vast majority of volcanic activity that poses a threat to human life. The tempo and magnitude of these eruptions depends on the physical conditions under which magmas are retained within the crust. Recently the case has been made that volcanic reservoirs are rarely molten and only capable of eruption for durations as brief as 1,000 years following magma recharge. If the "cold storage" model is generally applicable, then geophysical detection of melt beneath volcanoes is likely a sign of imminent eruption...
October 31, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27783643/cryptic-disc-structures-resembling-ediacaran-discoidal-fossils-from-the-lower-silurian-hellefjord-schist-arctic-norway
#6
Christopher L Kirkland, Breandán A MacGabhann, Brian L Kirkland, J Stephen Daly
The Hellefjord Schist, a volcaniclastic psammite-pelite formation in the Caledonides of Arctic Norway contains discoidal impressions and apparent tube casts that share morphological and taphonomic similarities to Neoproterozoic stem-holdfast forms. U-Pb zircon geochronology on the host metasediment indicates it was deposited between 437 ± 2 and 439 ± 3 Ma, but also indicates that an inferred basal conglomerate to this formation must be part of an older stratigraphic element, as it is cross-cut by a 546 ± 4 Ma pegmatite...
2016: PloS One
https://www.readbyqxmd.com/read/27749037/incorporation-of-thorium-in-the-zircon-structure-type-through-the-th1-xerx-sio4-1-x-po4-x-thorite-xenotime-solid-solution
#7
Adel Mesbah, Nicolas Clavier, M Janeth Lozano-Rodriguez, Stephanie Szenknect, Nicolas Dacheux
Pure powdered compounds with a general formula Th1-xErx(SiO4)1-x(PO4)x belonging to the zircon-xenotime family were successfully synthesized under hydrothermal conditions (250 °C, 7 days) as recently reported for the preparation of coffinite. Therefore, a thorough, combined PXRD, EDX, EXAFS, Raman, and FTIR analysis showed the formation of a solid solution in agreement with Vegard's law. Moreover, the examination of the local structure shows that the Th-O distances remain close to those found in ThSiO4, whereas the Er-O distances show a significant decrease from 2...
October 17, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/27715087/deformation-behavior-across-the-zircon-scheelite-phase-transition
#8
Binbin Yue, Fang Hong, Sébastien Merkel, Dayong Tan, Jinyuan Yan, Bin Chen, Ho-Kwang Mao
The pressure effects on plastic deformation and phase transformation mechanisms of materials are of great importance to both Earth science and technological applications. Zircon-type materials are abundant in both nature and the industrial field; however, there is still no in situ study of their deformation behavior. Here, by employing radial x-ray diffraction in a diamond anvil cell, we investigate the dislocation-induced texture evolution of zircon-type gadolinium vanadate (GdVO_{4}) in situ under pressure and across its phase transitions to its high-pressure polymorphs...
September 23, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27696864/probing-grain-boundary-chemistry-and-electronic-structure-in-proton-conducting-oxides-by-atom-probe-tomography
#9
Daniel Ryan Clark, Huayang Zhu, David R Diercks, Sandrine Ricote, Robert J Kee, Ali Almansoori, Brian P Gorman, Ryan P O'Hayre
A laser-assisted atom-probe-tomographic (LAAPT) method has been developed and applied to measure and characterize the three-dimensional atomic and electronic nanostructure at an yttrium-doped barium zirconate (BaZr0.9Y0.1O3-δ, BZY10) grain boundary. Proton-conducting perovskites, such as BZY10, are attracting intense interest for a variety of energy conversion applications. However, their implementation has been hindered, in part, because of high grain-boundary (GB) resistance that is attributed to a positive GB space-charge layer (SCL)...
October 3, 2016: Nano Letters
https://www.readbyqxmd.com/read/27682487/-health-status-of-dust-exposed-workers-in-a-precision-casting-enterprise
#10
B Yu, B M Ding, C H Fan, Q D Liu, L Ding, B S Wang, J Wang, H D Zhang, F Zhang
Objective: To investigate the health status of workers exposed to zircon sand and silica dust in a precision casting enterprise, and to provide a basis for the development of prevention and control measures. Methods: Occupational health examination, questionnaire survey, and field investigation of occupational health were performed for 176 male workers (18 workers in the zirconium dust exposure group, 109 in the non-zirconium dust exposure group, and 49 in the non-dust exposure group) in a precision casting enterprise, and a statistical analysis was performed for the data obtained...
July 20, 2016: Chinese Journal of Industrial Hygiene and Occupational Diseases
https://www.readbyqxmd.com/read/27617295/nanogeochronology-of-discordant-zircon-measured-by-atom-probe-microscopy-of-pb-enriched-dislocation-loops
#11
Emily M Peterman, Steven M Reddy, David W Saxey, David R Snoeyenbos, William D A Rickard, Denis Fougerouse, Andrew R C Kylander-Clark
Isotopic discordance is a common feature in zircon that can lead to an erroneous age determination, and it is attributed to the mobilization and escape of radiogenic Pb during its post-crystallization geological evolution. The degree of isotopic discordance measured at analytical scales of ~10 μm often differs among adjacent analysis locations, indicating heterogeneous distributions of Pb at shorter length scales. We use atom probe microscopy to establish the nature of these sites and the mechanisms by which they form...
September 2016: Science Advances
https://www.readbyqxmd.com/read/27614638/perovskite-type-titanate-zirconate-as-photocatalyst-for-textile-wastewater-treatment
#12
A M Ferrari-Lima, A C Ueda, E A Bergamo, R G Marques, E A V Ferri, C S Pinto, C A A Pereira, P H Yassue-Cordeiro, R P Souza
Calcium titanate zirconate, Ca(Ti(1-x)Zrx)O3 (CZT), powders have been synthesised by the polymeric precursor method. The structural analysis of the CZT powders was monitored by X-ray diffraction (XRD), photoacoustic spectroscopy (PAS) and textural analysis. The photocatalytic properties were evaluated by methylene blue (MB) decomposition and real textile wastewater (RTW) combined treatment (coagulation/flocculation/photocatalysis). Chemical oxygen demand (COD) of RTW was successfully reduced from 6195 mg L(-1) (untreated) to 662 mg L(-1) after coagulation/flocculation with a tannin-based coagulant (Tanfloc®) and finally to 471 mg L(-1) after combined treatment (coagulation/flocculation/photocatalysis) applying ultraviolet radiation and CaTiO3 as photocatalyst...
September 10, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27587151/s-shape-spring-sensor-sensing-specific-low-frequency-vibration-by-energy-harvesting
#13
Lan Zhang, Jian Lu, Ryohei Takei, Natsumi Makimoto, Toshihiro Itoh, Takeshi Kobayashi
We have developed a Si-based microelectromechanical systems sensor with high sensitivity for specific low-frequency vibration-sensing and energy-harvesting applications. The low-frequency vibration sensor contains a disk proof mass attached to two or three lead zirconate titanate (PZT) S-shape spring flexures. To obtain a faster and less expensive prototype, the design and optimization of the sensor structure are studied via finite-element method analysis. To validate the sensor structure to detect low-frequency vibration, the effects of geometrical dimensions, including the width and diameter of the S-shape spring of the proof mass, were analyzed and measured...
August 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27556470/monitoring-of-grouting-compactness-in-a-post-tensioning-tendon-duct-using-piezoceramic-transducers
#14
Tianyong Jiang, Qingzhao Kong, Wenxi Wang, Linsheng Huo, Gangbing Song
A post-tensioning tendon duct filled with grout can effectively prevent corrosion of the reinforcement, maintain bonding behavior between the reinforcement and concrete, and enhance the load bearing capacity of concrete structures. In practice, grouting of the post-tensioning tendon ducts always causes quality problems, which may reduce structural integrity and service life, and even cause accidents. However, monitoring of the grouting compactness is still a challenge due to the invisibility of the grout in the duct during the grouting process...
2016: Sensors
https://www.readbyqxmd.com/read/27538343/a-comparison-of-zircon-u-pb-age-results-of-the-red-clay-sequence-on-the-central-chinese-loess-plateau
#15
Hujun Gong, Junsheng Nie, Zhao Wang, Wenbin Peng, Rui Zhang, Yunxiang Zhang
Single grain zircon U-Pb geochronology has demonstrated great potentials in extracting tectonic and atmospheric circulation signal carried by aeolian, fluvial, and fluviolacustrine sediments. A routine in this sort of studies is analyzing 100-150 grains and then compares zircon U-Pb age spectra between the measured sample and the potential sources. Here we compared the zircon U-Pb age results of the late Miocene-Pliocene Red Clay sequence of two neighboring sites from the Chinese Loess Plateau where similar provenance signal is expected...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27532506/aesthetic-preformed-paediatric-crowns-systematic-review
#16
Elody Aiem, Violaine Smaïl-Faugeron, Michèle Muller-Bolla
BACKGROUND: Different aesthetic preformed crowns (APC) are proposed to restore decayed and damaged primary teeth because the stainless steel crowns (SSCs) do not satisfy parents concerned about aesthetic. AIM: The objective was to evaluate the clinical effectiveness of all types of APC for restoring primary teeth compared with conventional filling materials or other types of crowns. DESIGN: Relevant articles were searched in electronic databases of PubMed via MEDLINE and the Cochrane central register of controlled trials...
August 17, 2016: International Journal of Paediatric Dentistry
https://www.readbyqxmd.com/read/27505613/imaging-nanoscale-lattice-variations-by-machine-learning-of-x-ray-diffraction-microscopy-data
#17
Nouamane Laanait, Zhan Zhang, Christian M Schlepütz
We present a novel methodology based on machine learning to extract lattice variations in crystalline materials, at the nanoscale, from an x-ray Bragg diffraction-based imaging technique. By employing a full-field microscopy setup, we capture real space images of materials, with imaging contrast determined solely by the x-ray diffracted signal. The data sets that emanate from this imaging technique are a hybrid of real space information (image spatial support) and reciprocal lattice space information (image contrast), and are intrinsically multidimensional (5D)...
September 16, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27448957/indoor-radon-risk-associated-to-post-tectonic-biotite-granites-from-vila-pouca-de-aguiar-pluton-northern-portugal
#18
L M O Martins, M E P Gomes, R J S Teixeira, A J S C Pereira, L J P F Neves
At Vila Pouca de Aguiar area, northern Portugal, crops out a post-tectonic Variscan granite pluton, related with the Régua-Vila Real-Verín fault zone, comprising three types of biotite granites. Among these granites, PSG granite yield the highest average contents of U, probably due to its enrichment in accessory U-bearing minerals such as zircon. In the proximity of faults and joints, these granites are often affected by different degrees of hydrothermal alteration, forming reddish altered rocks, commonly known as "episyenites"...
November 2016: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/27410344/electrostrictive-effect-for-active-control-of-surface-plasmon-signals
#19
Lucas Karperien, Ribal Georges Sabat
Real-time surface plasmon modulation was achieved by electrically varying the pitch of a nanoscale surface relief diffraction grating inscribed on an azobenzene thin film covered with a layer of silver. The azobenzene film was spin coated on an electrostrictive Lead Lanthanum Zirconate Titanate (PLZT) ceramic substrate and a combination of DC bias and AC electric fields were applied longitudinally on the PLZT ceramic causing a change in the grating's pitch as well as the surface plasmon's resonance wavelength...
June 13, 2016: Optics Express
https://www.readbyqxmd.com/read/27375857/crystal-structure-of-bis-n-tert-butyl-benzamidinium-hexa-chlorido-zirconate-iv-di-chloro-methane-disolvate
#20
Zhi-Hao Jiang, Jian-Ping Zhao, Xiu-Ming Ma, Sheng-Di Bai
In the Zr(IV) complex anion of the title complex salt, [(C4H9)HNC(C6H5)NH2]2[ZrCl6]·2CH2Cl2, the Zr(IV) cation, located on an inversion centre, is coordinated by six Cl(-) anions in a distorted octa-hedral geometry with Zr-Cl distances in the range 2.433 (2)-2.4687 (19) Å; in the amidinium cation, the dihedral angle between the aromatic ring and [NCN] plane is 43.3 (4)°. In the crystal, the amidinium cations and [ZrCl6](2-) anions are linked by N-H⋯Cl hydrogen bonds, forming a two-dimensional network extending along the b axis; two di-chloro-methane solvent mol-ecules are linked by a pair of weak C-H⋯Cl hydrogen bonds, forming a centrosymmetric [CHCl]2 six-membered ring...
April 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
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