X-ray Diffraction Analysis of γ2 (Sn-Hg) Phase in High Copper Amalgams of Varying Mercury Content

Microstructures of high copper commercial amalgams containing varying amounts of mercury, ranging from 20% above to 25% below recommended values, were primarily investigated by x-ray diffraction. Mechanisms relating to the absence or presence of γ2 (Sn-Hg) phase in these amalgams were discussed in relation to the presence of copper and tin elements in their original alloys. The optimum mercury concentration in some amalgams was determined in order to keep them free of the γ2 (Sn-Hg) phase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66731/2/10.1177_00220345810600021001.pd

Low temperature characterization of modulation doped SiGe grown on bonded silicon-on-insulator

Modulation doped pseudomorphic Si0.87Ge0.13 strained quantum wells were grown on bonded silicon-on-insulator (SOI) substrates. Comparison with similar structures grown on bulk Si(100) wafers shows that the SOI material has higher mobility at low temperatures with a maximum value of 16 810 cm 2/V s for 2.05 × 1011 cm – 2 carries at 298 mK. Effective masses obtained from the temperature dependence of Shubnikov–de Haas oscillations have a value of (0.27 ± 0.02) m0 compared to (0.23 ± 0.02) m0 for quantum wells on Si(100) while the cyclotron resonance effective masses obtained at higher magnetic fields without consideration for nonparabolicity effects have values between 0.25 and 0.29 m0. Ratios of the transport and quantum lifetimes, tau/tau q=2.13 ± 0.10, were obtained for the SOI material that are, we believe, the highest reported for any pseudomorphic SiGe modulation doped structure and demonstrates that there is less interface roughness or charge scattering in the SOI material than in metal–oxide–semiconductor field effect transistors or other pseudomorphic SiGe modulation doped quantum wells

TwiddleNet: Smartphones as Personal Servers

TwiddleNet uses smartphones as personal servers to enable instant content capture and dissemination for firstresponders. It supports the information sharing needs of first responders in the early stages of an emergency response operation. In TwiddleNet, content, once captured, is automatically tagged and disseminated using one of the several networking channels available in smartphones. TwiddleNet pays special attention to minimizing the equipment, network set-up time, and content capture and dissemination effort. It can support small operations of emergency responders in the first 48-72 hours of an emergency response by using handheld devices based infrastructure and scale up to handle hundred of users with more robust backend infrastructure

A study on the thermal conductivity of compacted bentonites

Thermal conductivity of compacted bentonite is one of the most important properties in the design of high-level radioactive waste repositories where this material is proposed for use as a buffer. In the work described here, a thermal probe based on the hot wire method was used to measure the thermal conductivity of compacted bentonite specimens. The experimental results were analyzed to observe the effects of various factors (i.e. dry density, water content, hysteresis, degree of saturation and volumetric fraction of soil constituents) on the thermal conductivity. A linear correlation was proposed to predict the thermal conductivity of compacted bentonite based on experimentally observed relationship between the volumetric fraction of air and the thermal conductivity. The relevance of this correlation was finally analyzed together with others existing methods using experimental data on several compacted bentonites

Rapid fabrication of annuloplasty rings by electron beam melting

Electron Beam Melting (EBM) is an Additive Manufacturing (AM) technology capable of producing intricate parts by melting powder metal with the aid of an electron beam gun. EBM has facilitated the production of standard and customisable implants. Customizable implants such as orthopaedic implants, cranial implants and dental implants have already been developed and implanted successfully after being fabricated by AM technology. Other medical devices can also benefit from the possibilities offered by AM. An example of such a medical device would be the annuloplasty ring. Standard annuloplasty rings are implanted whenever a patient is diagnosed with mitral valve regurgitation. This problem arises when the mitral valve does not close properly, causing back leakage through the closed valve resulting in blood flowing to the atrium instead of the aorta during systole. The latest designs of annuloplasty rings allow restoration of the mitral annulus configuration to a saddle-shaped shape.peer-reviewe

Performance-Based Design Procedure of a Novel Friction-Based Cladding Connection for Blast Mitigation

Cladding systems are conventionally designed to provide buildings with environmental protection against wind, temperature, humidity, moisture, etc. Recently, researchers have proposed to leverage these systems to provide additional protection against manmade (e.g., blast) and natural (e.g., earthquakes, hurricanes) hazards. This can be achieved, for example, by redesigning the connection between the cladding and the structural system to provide energy dissipation via friction. While promising, the use of flexible cladding connection has only been considered for singular hazards. In this study, the authors propose a novel semi-active damping system to connect the cladding to the structure via a variable friction mechanism. By varying the normal force applied on friction plates through a system of adjustable toggles, it is possible to mitigate vibrations over a wide frequency range, therefore enabling mitigation of different types of hazards (i.e. to achieve multi-hazard resistance). In its passive in-situ mode, the device is designed to provide very high stiffness and friction resistance to mitigate the effects of blast. The objective of this paper is to enable a holistic integration of said device within the structural design process by developing a performance-based design procedure. The study will focus on the passive in-situ mode of the device, which will provide a stepping stone for the development of performance-based design procedures for its semi-active (i.e. actuated) capabilities. The proposed performance-based design procedure consists of the following: 1) determine the design performance criteria, including the blast properties and allowable connection gap between the cladding and structure; 2) select design properties for the cladding connection, including stiffness and damping; and 3) design a rubber impact bumper located between the structure and the cladding in order to mitigate slamming of the cladding into the structure for very high blast loads

Efficient molecular organic light-emitting diodes based on silole derivatives

Abstract We report the performance of molecular organic light-emitting diodes (MOLEDs) using silole derivatives as emissive and electron transport materials. Two siloles, namely 2,5-di-(3-biphenyl)-1,1-dimethyl-3,4-diphenylsilacyclopentadiene (PPSPP) and 1,2-bis(1-methyl-2,3,4,5,-tetraphenylsilacyclopentadienyl)ethane (2PSP), with high PL quantum yields of 94% and 85%, respectively, were used as emissive materials. Another silole, namely 2,5-bis-(2',2''-bipyridin-6-yl)-1,1-dimethyl-3,4-diphenylsilacyclopentadiene (PyPySPyPy), was used as the electron transport material. MOLEDs using these two siloles and NPB as the hole transport material show a low operating voltage of approximately 4.5 V at a luminance of 100 cd/m 2 and high external electroluminescence (EL) quantum efficiencies of 3.4% and 3.8%, respectively, at 100 A/m 2 . MOLEDs based on PPSPP exhibit a red-shifted EL spectrum which is assigned to an exciplex formed at the PPSPP:NPB interface. Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number

Realization of the farad from the dc quantum Hall effect with digitally-assisted impedance bridges

A new traceability chain for the derivation of the farad from dc quantum Hall effect has been implemented at INRIM. Main components of the chain are two new coaxial transformer bridges: a resistance ratio bridge, and a quadrature bridge, both operating at 1541 Hz. The bridges are energized and controlled with a polyphase direct-digital-synthesizer, which permits to achieve both main and auxiliary equilibria in an automated way; the bridges and do not include any variable inductive divider or variable impedance box. The relative uncertainty in the realization of the farad, at the level of 1000 pF, is estimated to be 64E-9. A first verification of the realization is given by a comparison with the maintained national capacitance standard, where an agreement between measurements within their relative combined uncertainty of 420E-9 is obtained.Comment: 15 pages, 11 figures, 3 table