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  • Molecular Diversity Preservation International  (31)
  • American Institute of Physics (AIP)  (11)
  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 63-67 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For the investigation of high-Z impurities in the ASDEX Upgrade tokamak a sublimation probe was developed and tested. With this probe it is possible to inject materials, that sublimate at temperatures from about 50 to 150 °C into the plasma through a controllable valve. For the investigation of the tungsten transport in ASDEX Upgrade the probe was operated with tungsten carbonyl. The flux of tungsten, which is difficult to determine directly because of the uncertain atomic data, can be determined using the fluxes of oxygen and carbon, the atomic data of which are better known. In this article the setup of the probe and first experiments are described. Here the layer of deposited tungsten was investigated and the number of emitted photons per ionization (the S/XB ratio) for the 400.8 nm line of W I was estimated. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 8061-8065 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: While the nuclear spin relaxation time changes in hydrating cement materials have been widely studied by various groups during the last 20 years, data on the self-diffusion behavior of the pore water during hydration of a cement paste are much scarcer. Taking advantage of improved spectrometer hardware for pulsed field gradient diffusometry and a specialized pulse sequence which is designed to compensate the detrimental effects of inner magnetic field gradients in the sample we have studied the water self-diffusion behavior in pastes prepared from white cement at various water/cement ratios. For the same mixtures, studies of the transverse spin relaxation behavior were also conducted. A comparison of the results from both techniques shows that the diffusion coefficient starts to decrease only much later than the relaxation times for all pastes studied. © 2001 American Institute of Physics.
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  • 13
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 1935-1938 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The pulsed field gradient nuclear magnetic resonance method is applied to study self-diffusion of ethane in beds of zeolite NaX for displacements which are orders of magnitude larger than the size of individual crystals. Comparison of the measured diffusivities with those calculated using simple gas kinetic theory indicates that for the same bed of NaX crystals the apparent tortuosity factor in the Knudsen regime is significantly larger than that in the bulk regime. This finding is tentatively attributed to the more pronounced geometrical trapping by surface imperfections in the Knudsen than in the bulk regime. Tortuosity factors, which are much larger in the Knudsen regime than in the bulk regime, were also recently obtained by dynamic Monte Carlo simulation of gas diffusion in various porous systems. © 2002 American Institute of Physics.
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  • 14
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2949-2951 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have developed a simple, fast, and flexible technique to measure optical scattering spectra of individual metallic nanoparticles. The particles are placed in an evanescent field produced by total internal reflection of light from a halogen lamp in a glass prism. The light scattered by individual particles is collected using a conventional microscope and is spectrally analyzed by a nitrogen-cooled charge-coupled-device array coupled to a spectrometer. This technique is employed to measure the effect of particle diameter on the dephasing time of the particle plasmon resonance in gold nanoparticles. We also demonstrate the use of this technique for measurements in liquids, which is important for the potential application of particle plasmons in chemical or biological nanosensors. © 2000 American Institute of Physics.
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  • 15
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The lattice orientations near the interface of chemical vapor deposited diamond films on Si(001) have been studied by orientation imaging microscopy. This technique is based on the automated analysis of electron backscatter Kikuchi diffraction patterns. The electron beam has been scanned in discrete steps over the reverse side of the diamond film after having removed the substrate. The obtained data have allowed us to determine the texture and to visualize quantitatively the orientational arrangement of and among individual diamond crystallites in the near-interface region. A comparison with the orientation of the substrate has proved the existence of epitaxially nucleated grains. A high amount of twinned diamond has been deduced from the pole figures and verified by analysis of orientation correlations between neighboring crystallites. Moreover, the grain boundary maps have allowed us to monitor and quantify directly the occurring twin boundaries. © 1994 American Institue of Physics.
    Type of Medium: Electronic Resource
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  • 16
    Publication Date: 2016-07-16
    Description: We show that double-gate ambipolar thin-film transistors can be operated to enhance minority carrier injection. The two gate potentials need to be significantly different for enhanced injection to be observed. This enhancement is highly beneficial in devices such as light-emitting transistors where balanced electron and hole injections lead to optimal performance. With ambipolar single-walled carbon nanotube semiconductors, we demonstrate that higher ambipolar currents are attained at lower source-drain voltages, which is desired for portable electronic applications, by employing double-gate structures. In addition, when the two gates are held at the same potential, the expected advantages of the double-gate transistors such as enhanced on-current are also observed.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 17
    Publication Date: 2014-09-24
    Description: We report on the marked improvements in key device characteristics of single walled carbon nanotube (SWCNT) field-effect transistors (FETs) by coating the active semiconductor with a fluoropolymer layer such as poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE). The observed improvements include: (i) A reduction in off-current by about an order of magnitude, (ii) a significant reduction in the variation of threshold voltage, and (iii) a reduction in bias stress-related instability and hysteresis present in device characteristics. These favorable changes in device characteristics also enhance circuit performance and the oscillation amplitude, oscillation frequency, and increase the yield of printed complementary 5-stage ring oscillators. The origins of these improvements are explored by exposing SWCNT FETs to a number of vapor phase polar molecules which produce similar effects on the FET characteristics as the PVDF-TrFE. Coating of the active SWCNT semiconductor layer with a fluoropolymer will be advantageous for the adoption of SWCNT FETs in a variety of printed electronics applications.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 18
    Publication Date: 2014-07-23
    Description: In this study, the char burnout characteristics of two German coals (a lignite and a high-volatile bituminous coal) were investigated using two different experimental configurations and optical techniques in two distinct laboratories for measurement of temperature and size of burning particles. The optical diagnostic hardware is quite different in the two systems, but both perform two-color pyrometry and optical sizing measurements on individual particles burning in isolation from each other in high-temperature laminar flows to characterize the char consumption kinetics. The performance of the specialized systems is compared for two different combustion atmospheres (with 6.6 and 12 vol.% O 2 ) and gas temperatures between 1700 and 1800 K. The measured particle temperatures and diameters are converted to char burning rate parameters for several residence times during the course of the particles’ burnout. The results confirm that comparable results are obtained with the two configurations, although higher levels of variability in the measured data were observed in the imaging-based pyrometer setup. Corresponding uncertainties in kinetics parameters were larger, and appear to be more sensitive to systematic measurement errors when lower oxygen contents are used in the experiments. Consequently, burnout experiments in environments with sufficiently high O 2 contents may be used to measure reliable char burning kinetics rates. Based on simulation results for the two coals, O 2 concentrations in the range 10%–30% are recommended for kinetic rate measurements on 100  μ m particles.
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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  • 19
    Publication Date: 2020-05-21
    Description: Patellofemoral (PF) disorders are considered a major clinical complication after total knee replacement (TKR). Malpositioning and design of the patellar component impacts knee joint dynamics, implant fixation and wear propagation. However, only a limited number of studies have addressed the biomechanical impact of the patellar component on PF dynamics and their results have been discussed controversially. To address these issues, we implemented a musculoskeletal multibody simulation (MMBS) study for the systematical analysis of the patellar component’s thickness and positioning on PF contact forces and kinematics during dynamic squat motion with virtually implanted unconstrained cruciate-retaining (CR)-TKR. The patellar button thickness clearly increased the contact forces in the PF joint (up to 27%). Similarly, the PF contact forces were affected by superior–inferior positioning (up to 16%) and mediolateral positioning (up to 8%) of the patellar button. PF kinematics was mostly affected by the mediolateral positioning and the thickness of the patellar component. A medialization of 3 mm caused a lateral patellar shift by up to 2.7 mm and lateral patellar tilt by up to 1.6°. However, deviations in the rotational positioning of the patellar button had minor effects on PF dynamics. Aiming at an optimal intraoperative patellar component alignment, the orthopedic surgeon should pay close attention to the patellar component thickness in combination with its mediolateral and superior–inferior positioning on the retropatellar surface. Our generated MMBS model provides systematic and reproducible insight into the effects of patellar component positioning and design on PF dynamics and has the potential to serve as a preoperative analysis tool.
    Electronic ISSN: 1996-1944
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 20
    Publication Date: 2019-01-03
    Description: Serum vitamin D levels negatively correlate with obesity and associated disorders such as non-alcoholic steatohepatitis (NASH). However, the mechanisms linking low vitamin D (VD) status to disease progression are not completely understood. In this study, we analyzed the effect of VD treatment on NASH in mice. C57BL6/J mice were fed a high-fat/high-sugar diet (HFSD) containing low amounts of VD for 16 weeks to induce obesity, NASH and liver fibrosis. The effects of preventive and interventional VD treatment were studied on the level of liver histology and hepatic/intestinal gene expression. Interestingly, preventive and to a lesser extent also interventional VD treatment resulted in improvements of liver histology. This included a significant decrease of steatosis, a trend towards lower non-alcoholic fatty liver disease (NAFLD) activity score and a slight non-significant decrease of fibrosis in the preventive treatment group. In line with these changes, preventive VD treatment reduced the hepatic expression of lipogenic, inflammatory and pro-fibrotic genes. Notably, these beneficial effects occurred in conjunction with a reduction of intestinal inflammation. Together, our observations suggest that timely initiation of VD supplementation (preventive vs. interventional) is a critical determinant of treatment outcome in NASH. In the applied animal model, the improvements of liver histology occurred in conjunction with reduced inflammation in the gut, suggesting a potential relevance of vitamin D as a therapeutic agent acting on the gut–liver axis.
    Electronic ISSN: 2072-6643
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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