bluuebunny/crossref_metadata_2025 huggingface dataset:
Akzidentelle Lithiumintoxikation
Authors: Fiegler  , Liechti  , Bodmer  , Bruggisser
Published: June 2009

Wir berichten über einen 75-jährigen Patienten mit bekannter bipolar affektiver Störung und bestehender Lithiumtherapie, der wegen arterieller Hypotonie und Vigilanzminderung auf die Notfallstation zugewiesen wurde. Einen Monat vor Eintritt wurde aufgrund einer kardialen Dekompensation eine Herzinsuffizienztherapie mit Betablocker, ACE-Hemmer und einem Schleifendiuretikum eingeleitet. Bei Spitaleintritt wurden ein prärenales Nierenversagen sowie eine Pneumonie diagnostiziert. Laborchemisch zeigte sich ein erhöhter Lithiumspiegel. Im Verlauf kam es zu einer progredienten neurologischen Verschlechterung mit GCS-Abfall auf 7 Punkte, einer Blickdeviation nach oben, einem erhöhten Muskeltonus sowie generalisierten spontanen Myoklonien. Nach Volumengabe und rascher Normalisierung der Nierenfunktion verbesserte sich das neurologische Zustandsbild im Verlauf von zwei Wochen. Aufgrund der typischen Klinik, der Reversibilität der neurologischen Auffälligkeiten sowie Ausschluss hirnorganischer Ursachen, konnte die Diagnose einer chronischen Lithiumintoxikation gestellt werden.
Webbasiertes audiovisuelles Patienten-Informationssystem. Eine Pilotstudie über die präoperative Patientenaufklärung
Authors: Hermann  , Gautschi  , Hildebrandt  , Fournier
Published: June 2009

Im klinischen Alltag besteht ein wesentlicher Teil der ärztlichen Tätigkeit darin, Patienten über medizinische Diagnosen und insbesondere über das Vorgehen operativer Eingriffe zu informieren. In diesen Gesprächen wird das Krankheitsbild, der Ablauf im Spital vor und nach der Operation sowie das Vorgehen während der Operation erklärt. Aus rechtlicher Sicht muss von ärztlicher Seite während des Gesprächs auf alle möglichen Risiken des Eingriffs hingewiesen werden. Um die Informationsvermittlung zu optimieren, werden während des Gesprächs Hilfsmittel wie Zeichnungen, Bilder, Röntgenbilder und Modelle verwendet. Nach einer rein mündlichen Aufklärung wird jedoch nur ein geringer Prozentsatz der Informationen vom Patienten aufgenommen. Damit die Patienten besser und frühzeitig über medizinische Details und interne Abläufe vor einer geplanten Operation informiert werden können, haben wir ein webbasiertes Informationsportal mit einer Kombination aus Bild, Text, Ton und Video über chirurgische Eingriffe entwickelt. Durch den Einsatz dieses Patienten-Informationssystems in der Aufklärungskaskade kann die Patientenzufriedenheit wesentlich verbessert werden. Zusätzlich kann der Einsatz des webbasierten multimedialen Informationsportals für das ärztliche Personal zu einer wesentlichen Zeitersparnis führen.
Wenn das Atmen Mühe macht: Ursachen und Typen der Atemnot
Authors: Brack
Published: June 2009

Atemnot ist die unangenehme Empfindung der eigenen Atmung, die von Gesunden in Ruhe kaum wahrgenommen wird. Wie der Schmerz ist die Atemnot ein Warnzeichen des Körpers, welcher Korrekturmechanismen zur Linderung der Dyspnoe aktiviert. Dyspnoe entsteht durch die zentralnervöse Verarbeitung verschiedener Rückmeldungen des Atemapparates. Neben der zentralen Verarbeitung von Signalen aus den Atemmuskeln, der Brustwand, den Atemwegen und der Lunge werden auch die arteriellen Partialdrücke von Kohlendioxid und Sauerstoff ständig gemessen und reflektorisch konstant gehalten. Atemnot wird je nach deren Ursache verschieden wahrgenommen. Lufthunger bei erhöhtem Kohlendioxid, angestrengte Atmung bei erhöhtem Atemminutenvolumen und thorakales Engegefühl bei Asthma sind die drei wichtigsten Qualitäten der Dyspnoe. Das Atemzentrum sucht vor allem bei chronischer Dyspnoe nach einem Atemmuster, welches Dyspnoe möglichst vermeidet. Wegen des engen Zusammenspiels zwischen autonomer Regulation und kortikaler Modulation zur Atemsteuerung kann die bewusste, willkürliche Atmung auch andere autonome Systeme und die Schmerzempfindung wesentlich beeinflussen.
35-jähriger Maurer mit Durchblutungsstörungen der linken Hand
Authors: Rosemann  , Senn  , Rosemann
Published: June 2009

Ein 35-jähriger Patient stellt sich mit Kälte, Blässe sowie einem Taubheitsgefühl und Schmerzen am Ringfinger (Dig. IV) der linken Hand vor. Der Allen-Test ist pathologisch, die Angiographie zeigt einen Verschluss der A. ulnaris ab Höhe des Hamulus ossis hamati über zirka 4 cm Länge. Es erfolgt die Therapie mit Prostavasin und ASS 100 sowie eine Nikotinkarenz. Nach 10 Tagen ist der Patient subjektiv beschwerdefrei.
Source locations of narrowband radio emissions detected at Saturn
Authors: Ye Sheng‐Yi , Gurnett D. A. , Fischer G. , Cecconi B. , Menietti J. D. , Kurth W. S. , Wang Z. , Hospodarsky G. B. , Zarka P. , Lecacheux A.
Published: June 2009

Since Cassini's arrival at Saturn in 2004, the Radio and Plasma Wave Science instrument has detected numerous narrowband (NB) radio emission events. These emissions, mostly detected around 5 and 20 kHz, usually occur periodically for several days after intensifications of Saturn kilometric radiation. We present calculations based on an electron density profile of Saturn's plasma torus and a dipole magnetic field model showing that the NB emissions originate from the northern and southern edges of Saturn's plasma torus at L shells ∼ 8 to 10 for 5‐kHz NB and L ∼ 4 to 7 for 20‐kHz NB. In many cases, Cassini passes through the source region of the 20‐kHz NB, as indicated by intense electrostatic upper hybrid (ESUH) waves in close proximity to electromagnetic emissions on spectrograms. The positions of the spacecraft when intense ESUH waves are observed agree with the model predictions of the NB source locations. Source locations determined by goniopolarimetric (also known as direction‐finding) analysis of the NB emissions also support the above results, although sometimes the directions of arrival point toward the region interior to Saturn's plasma torus. A polarization reversal technique is applied to localize the NB emissions observed during spacecraft rotation, on the basis of the fact that the source is within the antenna plane when the apparent circular polarization degree switches sign. The NB emissions are found to be L‐O mode polarized, which is consistent with the prediction of linear/nonlinear mode conversion theory. It is also found that sometimes right‐hand polarized NB emissions are generated at second harmonic frequencies of the 20‐kHz NB; in which case, wave‐wave interactions between oppositely propagating ESUH waves may play an important role in the mode conversion process.
Wormhole formation in dissolving fractures
Authors: Szymczak P. , Ladd A. J. C.
Published: June 2009

We investigate the dissolution of artificial fractures with three‐dimensional, pore‐scale numerical simulations. The fluid velocity in the fracture space was determined from a lattice Boltzmann method, and a stochastic solver was used for the transport of dissolved species. Numerical simulations were used to study conditions under which long conduits (wormholes) form in an initially rough but spatially homogeneous fracture. The effects of flow rate, mineral dissolution rate, and geometrical properties of the fracture were investigated, and the optimal conditions for wormhole formation were determined.
Effects of ambient velocity shear on nonlinear internal wave associated mixing at the Columbia River plume front
Authors: Pan Jiayi , Jay David A.
Published: June 2009

Large‐amplitude nonlinear internal waves (NLIWs) are frequently observed propagating away from Columbia River tidal plume fronts. They are generated because of the deceleration of the frontal bulge. During the River Influences on Shelf Ecosystems project cruises, the velocity, density structure and acoustic backscatter of the plume fronts and frontal NLIWs were observed using a towed vehicle, vessel‐mounted instrumentation, and a vessel X band radar. These observations indicate that in the presence of strong ambient velocity shear, the NLIWs with maximum amplitudes occur well below the density interface and at a depth deeper than in the absence of shear. This deepening of the NLIW shear is associated with intensified vertical mixing below the interface. This is consistent with a dynamic analysis of NLIWs under the influence of sheared ambient flow, obtained from a high‐order KdV model. There are two mechanisms responsible for the vertical turbulent mixing intensification. The nonlinear interaction between ambient shear and the NLIWs increases total velocity shear and causes the gradient Richardson number Rig to decrease below a critical value in certain depth ranges. Also, because of the presence of the ambient shear, the maximum NLIW velocity shear occurs at a depth below the density interface where there is less stratification.
Beaufort Gyre freshwater reservoir: State and variability from observations
Authors: Proshutinsky Andrey , Krishfield Richard , Timmermans Mary‐Louise , Toole John , Carmack Eddy , McLaughlin Fiona , Williams William J. , Zimmermann Sarah , Itoh Motoyo , Shimada Koji
Published: June 2009

We investigate basin‐scale mechanisms regulating anomalies in freshwater content (FWC) in the Beaufort Gyre (BG) of the Arctic Ocean using historical observations and data collected in 2003–2007. Specifically, the mean annual cycle and interannual and decadal FWC variability are explored. The major cause of the large FWC in the BG is the process of Ekman pumping (EP) due to the Arctic High anticyclonic circulation centered in the BG. The mean seasonal cycle of liquid FWC is a result of interplay between the mechanical (EP) and thermal (ice transformations) factors and has two peaks. One peak occurs around June–July when the sea ice thickness reaches its minimum (maximum ice melt). The second maximum is observed in November–January when wind curl is strongest (maximum EP) and the salt input from the growing ice has not yet reached its maximum. Interannual changes in FWC during 2003–2007 are characterized by a strong positive trend in the region varying by location with a maximum of approximately 170 cm a−1 in the center of EP influenced region. Decadal FWC variability in the period 1950–2000 is dominated by a significant change in the 1990s forced by an atmospheric circulation regime change. The center of maximum FWC shifted to the southeast and appeared to contract in area relative to the pre‐1990s climatology. In spite of the areal reduction, the spatially integrated FWC increased by over 1000 km3 relative to climatology.
Wave‐current interaction in nearshore shear instability analyzed with a vortex force formalism
Authors: Uchiyama Yusuke , McWilliams James C. , Restrepo Juan M.
Published: June 2009

We examine wave‐current interactions in littoral current shear instabilities above a single‐barred beach using a fully coupled wave and barotropic current model based on the multiscale asymptotic theory derived by McWilliams et al. (2004). This Eulerian wave‐averaged model captures wave effects on currents (WEC) in a manner that leads to simple interpretations. The dynamically conservative WEC are the vortex force and material transport by Stokes drift and the sea level adjustment by wave set‐down and setup. In the setting considered here there are also important current effects on the waves (CEW): induction of a Doppler shift by currents and surface elevation variation in the wave dispersion relation. Nonconservative effects, due to wave breaking and bottom drag, also play a prominent role in generating and equilibrating the mean alongshore current, consistent with prior studies. High bottom drag stabilizes the currents, while a drag reduction below a critical threshold value leads to shear instability with nearly periodic, alongshore‐fluctuating eddies. An even smaller bottom drag yields irregular eddy motions with intermittent offshore eruption of vortex pairs from the meandering alongshore current. Several alternative parameterizations of the bottom drag are contrasted here. Including CEW in the model leads to a delay in the onset of the instability, a suppression of fluctuations in cross‐shore velocity and lateral Reynolds stress, and an enhancement of the mean alongshore velocity. The WEC increase the Reynolds stress in the offshore region, and the conservative vortex force and mean advection are comparable in magnitude to the breaking acceleration and bottom drag. Conversely, the CEW reduce the Reynolds stress and attenuate the breaking acceleration through refractive focusing by current shear. Overall, the WEC enhance the instantaneous cross‐shore momentum flux to induce more energetic eddy motions and retard the mean alongshore current, while the CEW stabilize the fluctuations and help maintain a strong mean current.
Sensitivity analysis, calibration, and testing of a distributed hydrological model using error‐based weighting and one objective function
Authors: Foglia L. , Hill M. C. , Mehl S. W. , Burlando P.
Published: June 2009

We evaluate the utility of three interrelated means of using data to calibrate the fully distributed rainfall‐runoff model TOPKAPI as applied to the Maggia Valley drainage area in Switzerland. The use of error‐based weighting of observation and prior information data, local sensitivity analysis, and single‐objective function nonlinear regression provides quantitative evaluation of sensitivity of the 35 model parameters to the data, identification of data types most important to the calibration, and identification of correlations among parameters that contribute to nonuniqueness. Sensitivity analysis required only 71 model runs, and regression required about 50 model runs. The approach presented appears to be ideal for evaluation of models with long run times or as a preliminary step to more computationally demanding methods. The statistics used include composite scaled sensitivities, parameter correlation coefficients, leverage, Cook's D, and DFBETAS. Tests suggest predictive ability of the calibrated model typical of hydrologic models.
Intraplate volcanism with complex age‐distance patterns: A case for small‐scale sublithospheric convection
Authors: Ballmer M. D. , van Hunen J. , Ito G. , Bianco T. A. , Tackley P. J.
Published: June 2009

Many volcano chains in the Pacific do not follow the most fundamental predictions of hot spot theory in terms of geographic age progressions. One possible explanation for non–hot spot intraplate volcanism is small‐scale sublithospheric convection (SSC), and we explore this concept using 3‐D numerical models that simulate melting with rheology laws that account for the effects of dehydration. SSC spontaneously self‐organizes beneath relatively mature oceanic lithosphere. Whenever this lithosphere is sufficiently young and thin, SSC replaces the shallow layer of harzburgite, which was formed by partial melting at the mid‐ocean ridge, with fresh peridotite. This mechanism enables magma generation without any preexisting thermochemical anomalies. However, the additional effect of melting‐induced dehydration to stiffen the harzburgite requires lower background viscosities to allow for vigorous SSC, overturn of the compositional stratification, and related magmatism. The intrinsic stiffness of the dehydrated harzburgite furthermore restricts penetration of SSC into very shallow and cooler levels. On the one hand, such a restriction precludes high degrees of melting, but on the other hand, it slows asthenospheric cooling and thus prolongs the duration of melting (to ∼25 Ma). Volcanism over such an elongated melting anomaly continues for at least 10–20 Ma and occurs on seafloor ages of ∼20 to ∼60 Ma. These seafloor ages increase with increasing mantle temperature due to the effect of forming a thicker harzburgite layer from more extensive mid‐ocean ridge melting. The long durations of volcanism predicted reconcile observations of extended activity of individual seamounts and synchronous activity over great distances along some volcanic chains. SSC thus gives an explanation for previously enigmatic volcano ages along the Line Islands and the Gilbert and Pukapuka ridges, as well as along the individual subchains of the Wakes, Marshalls, and Cook‐Australs.
Rates of sea‐level change over the past century in a geocentric reference frame
Authors: Wöppelmann G. , Letetrel C. , Santamaria A. , Bouin M.‐N. , Collilieux X. , Altamimi Z. , Williams S. D. P. , Miguez B. Martin
Published: June 2009

The results from a carefully implemented GPS analysis, using a strategy adapted to determine accurate vertical station velocities, are presented. The stochastic properties of our globally distributed GPS position time series were inferred, allowing the computation of reliable velocity uncertainties. Most uncertainties were several times smaller than the 1–3 mm/yr global sea level change, and hence the vertical velocities could be applied to correct the long tide gauge records for land motion. The sea level trends obtained in the ITRF2005 reference frame are more consistent than in the ITRF2000 or corrected for Glacial‐Isostatic Adjustment (GIA) model predictions, both on the global and the regional scale, leading to a reconciled global rate of geocentric sea level rise of 1.61 ± 0.19mm/yr over the past century in good agreement with the most recent estimates.
A long‐term data set of globally averaged thermospheric total mass density
Authors: Emmert J. T.
Published: June 2009

We present a long‐term data set, available on the CEDAR Data System, of globally averaged thermospheric total mass density derived from the orbits of ∼5000 objects. The data cover the years 1967–2007 at heights from 200 to 600 km. The data have a temporal resolution of 3–6 days, a typical short‐term precision of ±2%, and a long‐term accuracy of 5–10%. We describe in detail the procedure used to generate the data set, provide an example of its scientific use, and discuss its limitations.
Effects of inertia and directionality on flow and transport in a rough asymmetric fracture
Authors: Cardenas M. Bayani , Slottke Donald T. , Ketcham Richard A. , Sharp John M.
Published: June 2009

Two‐dimensional flow and transport simulations are conducted for a 15‐cm‐long fracture mapped via X‐ray computed tomography. The simulations consider either Navier‐Stokes equation (NSE) based flow or Stokes equation (SE) based flow and are run for opposing directions. NSE and SE solutions deviate at larger bulk velocity, and the errors are sensitive to fracture geometry. Transport in all cases is non‐Fickian, owing mainly to the presence of a large eddy, and exhibits power law residence time distributions (RTDs). The tailing is more persistent at higher Reynolds numbers (Re), with the exponents of the power law RTDs related to Re via a power function, and becomes asymptotic at higher Re. The late‐time portion of the RTD changes with flow direction and is also sensitive to whether the flow is represented by the NSE or the SE. The sensitivity of transport to flow direction and formulation is primarily driven by varying eddy geometry under the different conditions. Our study opens the path to developing robust and mechanistic continuum‐scale models of solute transport in fractured geologic media.
NK cells enhance the induction of CTL responses by IL‐15 monocyte‐derived dendritic cells
Authors: Hardy Melinda Y , Kassianos Andrew J , Vulink Annelie , Wilkinson Ray , Jongbloed Sarah L , Hart Derek N J , Radford Kristen J
Published: June 2009

Dendritic cells differentiated from monocytes (MoDC) in the presence of GM‐CSF and IL‐15 (IL‐15 MoDC) exhibit superior migration and cytotoxic T‐lymphocyte (CTL) induction compared with MoDC differentiated in IL‐4 and GM‐CSF (IL‐4 MoDC) and are promising candidates for DC immunotherapy. We explored the mechanisms by which IL‐15 MoDC induce CTL. IL‐15 MoDC expressed higher levels of CD40 and secreted high levels of TNF‐α, but little or no IL‐12p70 compared with IL‐4 MoDC. Despite immuno‐selecting monocytes to >97% purity before MoDC generation, a tiny population (0.2%) of natural killer (NK) cells was identified that was increased sevenfold during IL‐15 MoDC, but not IL‐4 MoDC differentiation. These NK cells produced high levels of IFN‐γ and were responsible for the enhanced CTL‐inducing capacity of the IL‐15 MoDC, but not for their increased expression of CD40 or secretion of TNF‐α. Interestingly, a proportion of IL‐15 MoDC were found to express the NK cell marker, CD56, but these did not secrete IFN‐γ. These data implicate a role for small percentages of NK cells in the enhanced capacity of IL‐15 MoDC to induce tumour‐specific CTL independent of IL‐12p70.
Biosynthesis and bioproduction of coenzyme Q10 by yeasts and other organisms
Authors: Kawamukai Makoto
Published: June 2009

CoQ (coenzyme Q), an isoprenylated benzoquinone, is a well‐known component of the electron‐transfer system in eukaryotes. The main role of CoQ is to transfer electrons from NADH dehydrogenase and succinate dehydrogenase to CoQ:cytochrome c reductase in the respiratory chain. However, recent evidence indicates that an involvement in respiration is not the only role of CoQ. The second apparent role of CoQ is its anti‐oxidation property, and other novel roles for CoQ, such as in disulfide‐bond formation, sulfide oxidation and pyrimidine metabolism, have been reported. CoQ10, having ten isoprene units in the isoprenoid side chain, has been used as a medicine and is now commercially popular as a food supplement. Two yeast species, namely the budding yeast Saccharomyces cerevisiae, which produces CoQ6, and the fission yeast Schizosaccharomyces pombe, which produces CoQ10, are the main subjects of the present minireview because they have greatly contributed to our basic knowledge of CoQ biosynthesis among eukaryotes. The biosynthetic pathway that converts p‐hydroxybenzoate into CoQ consists of eight steps in yeasts. The five enzymes involved in the biosynthetic pathway have been identified in both yeasts, yet the functions of three proteins were still not known. Analyses of the biosynthetic pathway in yeasts also contribute to the understanding of human genetic diseases related to CoQ deficiency. In the present minireview I focus on the biochemical and commercial aspects of CoQ in yeasts and in other organisms for comparison.
Production of heterologous proteins using the fission‐yeast (Schizosaccharomyces pombe) expression system
Authors: Takegawa Kaoru , Tohda Hideki , Sasaki Mayumi , Idiris Alimjan , Ohashi Takao , Mukaiyama Hiroyuki , Giga‐Hama Yuko , Kumagai Hiromichi
Published: June 2009

The fission yeast Schizosaccharomyces pombe is a particularly useful model for studying the function and regulation of genes from higher eukaryotes. The genome of Sc. pombe has been sequenced, and DNA microarray, proteome and transcriptome analyses have been carried out. Among the well‐characterized yeast species, Sc. pombe is considered an attractive host for the production of heterologous proteins. Expression vectors for high‐level expression in Sc. pombe have been developed and many foreign proteins have been successfully expressed. However, further improvements in the protein‐expressing host systems are still required for the production of heterologous proteins involved in post‐translational modification, metabolism and intracellular trafficking. This minireview focuses on recent advances in heterologous protein production by use of engineered fission‐yeast strains.
Inverse momentum expectation values for hydrogenic systems
Authors: Delbourgo R. , Elliott D.
Published: June 2009

By using the Fourier transforms of the general hydrogenic bound state wave functions (as ultraspherical polynomials), one may find expectation values of arbitrary functions of momentum p. In this manner the effect of a reciprocity perturbation b/p can be evaluated for all hydrogenic states.
Local and average structures of the proton conducting Y-doped BaCeO3 from neutron diffraction and neutron pair distribution function analysis
Authors: Malavasi Lorenzo , Kim HyunJeong , Proffen Thomas
Published: June 2009

In this paper we investigated the most important family of proton conducting oxides, i.e., cerates, by means of neutron diffraction and of pair distribution function analysis (PDF). The paper describes the structural effects of Y-doping and water incorporation in cerates proton conductors from a viewpoint of the average structure (determined from diffraction) and the local structure (determined from PDF analysis).
Amorphous clusters in Co implanted ZnO induced by boron preimplantation
Authors: Potzger K. , Shalimov A. , Zhou Shengqiang , Schmidt H. , Mücklich A. , Helm M. , Fassbender J. , Liberati M. , Arenholz E.
Published: June 2009

We demonstrate the formation of superparamagnetic/ferromagnetic regions within ZnO(0001) single crystals sequentially implanted with B and Co. While the preimplantation with B plays a minor role for the electrical transport properties, its presence leads to the formation of amorphous phases. Moreover, B acts strongly, reducing the implanted Co. Thus, the origin of the ferromagnetic ordering in local clusters with large Co concentration is itinerant d-electron as in the case of metallic Co. The amorphous Co-based phases are nondetectable by common x-ray diffraction.
Phonon-coupled trap-assisted charge injection in metal-nitride-oxide-silicon/silicon-oxide-nitride-oxide-silicon structures
Authors: Nasyrov K. A. , Shaimeev S. S. , Gritsenko V. A. , Han J. H.
Published: June 2009

A phonon-coupled trap model is proposed for trap-assisted injection mechanism in silicon-oxide-nitride-oxide-silicon (SONOS)/metal-nitride-oxide-silicon (MNOS) structures at low voltages. On the basis of this model, a theory of charge injection in SONOS/MNOS has been developed. Charge injection experimental data was fitted by this theory. Obtained trap parameters are close to those previously reported [K. A. Nasyrov et al., J. Appl. Phys. 96, 4293 (2004)], where the current dependence on temperature and electric field was investigated in MNOS.
Anomalous transport induced by sheath instability in Hall effect thrusters
Authors: Taccogna Francesco , Longo Savino , Capitelli Mario , Schneider Ralf
Published: June 2009

It is well recognized to ascribe the anomalous cross-field conductivity inside Hall-effect thrusters to fluctuation-induced transport due to gradient-driven instabilities (Rayleigh or electron drift) and to electron-wall interaction (near-wall conductivity). In this letter, we have performed numerical experiments showing the possibility of another mechanism inducing azimuthal fluctuations: the lateral sheath instability. It is created by a negative differential resistance of the current-voltage I-V characteristic of the floating wall as a consequence of high secondary electron emission. The contribution from this effect to the anomalous axial current is calculated and it accounts of more than 80% of the experimental value.
Self-oscillation conditions of a resonant nanoelectromechanical mass sensor
Authors: Colinet Eric , Duraffourg Laurent , Labarthe Sébastien , Hentz Sébastien , Robert Philippe , Andreucci Philippe
Published: June 2009

This article presents a comprehensive study and design methodology of cointegrated oscillators for nanoscale mass sensing applications based on resonant nanoelectromechanical system (NEMS). In particular, a comparison is provided between the capacitive and the piezoresistive transduction schemes in terms of overall sensor performance. The developed model is clearly in accordance with the general experimental observations obtained for NEMS-based mass detection. The piezoresistive devices are more sensitive (up to 10 zg/√Hz) than capacitive ones (close to 100 zg/√Hz) since they can work at higher frequency. Moreover, the high doped silicon piezoresistive gauge, which is of great interest for very large scale integration, shows similar theoretical resolution to that of the metallic gauge already used experimentally.
Converse magnetoelectric effects in a galfenol and lead zirconate titanate bilayer
Authors: Fetisov Y. K. , Kamentsev K. E. , Chashin D. V. , Fetisov L. Y. , Srinivasan G.
Published: June 2009

Polycrystalline samples of galfenol Fe1−xGax (x=0.17–0.3) have been prepared and used in a bilayer with lead zirconate titanate for studies on the magnetoelectric (ME) effect. The converse ME effect which is the magnetic response of the sample to an applied ac electric field has been investigated. Piezoelectric deformations due the electric field result in an induced magnetization in galfenol that is measured as a voltage U in a pick-up coil wound on the bilayer. A resonance enhancement in the magnitude of U is evident for bending oscillations and longitudinal acoustic oscillations in the bilayer. Data on U as a function of the strength and orientation of bias field H show a maximum in ME coupling strength for in-plane component of H≈250Oe. The data have been analyzed in terms of H dependence of the magnetostriction for galfenol. The converse ME coupling is strong enough for use of the bilayer as a sensor of magnetic and electric fields.
Photofilling of intermediate bands
Authors: Strandberg Rune , Reenaas Turid Worren
Published: June 2009

A detailed balance model for the intermediate band (IB) solar cell has been developed. The model allows the electron concentration in the IB to vary and assumes a linear relation between this concentration and the absorption coefficients related to transitions over the subband gaps. Numerical results show that for IBs with densities of states typical for quantum dot-superlattices it is possible to sustain a useful population of photogenerated electrons in the IB when the cell is exposed to concentrated light. For unconcentrated light the IB must be partially filled by means of doping to achieve high efficiencies within reasonable optical path lengths. The filling of the IB is shown to vary with light intensity, cell voltage, density of IB-states, and the positioning of the IB in the main band gap both for cells that are partially filled by doping and for photofilled cells.
Coercivity of bulk anisotropic nanocomposite Sm(CoFeTi)8–10 magnets
Authors: Huang M. Q. , Turgut Z. , Chen Z. M. , Shen Y. H. , Lee D. , Higgins A. , Chen C. H. , Liu S. , Liu J. F. , Horwath J. C. , Fingers R. T.
Published: June 2009

The present study investigates the effects of nonmagnetic metal additions on Sm(CobalFe0.2Ti0.05MxB0.01)z (x=0–0.04 and z=8–10) based melt-spun alloys. M=Nb, Ga, Cu, and Al were selected to form anisotropic nanocomposite bulk magnets via hot pressing followed by a hot deformation. The effects of Nb, Ga, Cu, and Al substitutions on intrinsic coercivity Hci and possible mechanisms behind the improvement in Hci, such as phase formations, anisotropy field HA, and microstructure were investigated. Experimental results indicated an over 20%–50% enhancement in Hci after hot deformation (HD) with Nb, Ga, and Cu additions for magnets with z=8 and z=10. Especially with the Nb addition, the Hci improved from 8.7 to 12 kOe for the z=8 magnet, and from 5 to 11 kOe for the z=10 magnet. An unusual enhancement in Hci, from 9 kOe after hot pressing (HP) at 700 °C to 11 kOe after HD at 850 °C, was observed in the Nb-doped magnet with z=10. Our analysis on possible mechanisms behind the improvement in Hci indicated that Ga and Cu atoms tend to accompany and thus likely to stabilize a 1:5H phase, which possesses a higher anisotropy field HA, resulting in an improvement of Hci. Nb atoms tend to localize at the grain boundaries of (1:5H or 2:17R) phases and form a Nb-rich CoFe phase with average sizes around 50 nm. This phase is believed to suppress grain growth during HP and HD resulting in a stronger Hci. A subgrain structure (∼50 nm) within the apparently larger grains (a few hundred nanometers) of 1:5H or 2:17R phases was observed in the Nb-doped HD-magnet of z=10. The formation of these subgrains could be the mechanism responsible for increased Hci values after HD. Al atoms did not show any particular location preference and positive effect on Hci. The highest (BH)max of 13.4 MG Oe was obtained on anisotropic magnets of Sm(Co0.74Fe0.2Ti0.05B0.01)8.
Hard x-ray response of pixellated CdZnTe detectors
Authors: Abbene L. , Del Sordo S. , Caroli E. , Gerardi G. , Raso G. , Caccia S. , Bertuccio G.
Published: June 2009

In recent years, the development of cadmium zinc telluride (CdZnTe) detectors for x-ray and gamma ray spectrometry has grown rapidly. The good room temperature performance and the high spatial resolution of pixellated CdZnTe detectors make them very attractive in space-borne x-ray astronomy, mainly as focal plane detectors for the new generation of hard x-ray focusing telescopes. In this work, we investigated on the spectroscopic performance of two pixellated CdZnTe detectors coupled with a custom low noise and low power readout application specific integrated circuit (ASIC). The detectors (10×10×1 and 10×10×2 mm3 single crystals) have an anode layout based on an array of 256 pixels with a geometric pitch of 0.5 mm. The ASIC, fabricated in 0.8 μm BiCMOS technology, is equipped with eight independent channels (preamplifier and shaper) and characterized by low power consumption (0.5 mW/channel) and low noise (150–500 electrons rms). The spectroscopic results point out the good energy resolution of both detectors at room temperature [5.8% full width at half maximum (FWHM) at 59.5 keV for the 1 mm thick detector; 5.5% FWHM at 59.5 keV for the 2 mm thick detector) and low tailing in the measured spectra, confirming the single charge carrier sensing properties of the CdZnTe detectors equipped with a pixellated anode layout. Temperature measurements show optimum performance of the system (detector and electronics) at T=10 °C and performance degradation at lower temperatures. The detectors and the ASIC were developed by our collaboration as two small focal plane detector prototypes for hard x-ray multilayer telescopes operating in the 20–70 keV energy range.
Investigating the exchange bias in multilayer triangular nanorings
Authors: Jain S. , Tripathy D. , Adeyeye A. O.
Published: June 2009

Exchange bias effects have been systematically investigated in individual spin valve triangular rings using the synchronous transport measurement technique. Preferential pinning of antiferromagnetic (AFM) layer and ferromagnetic (FM) layer domain walls at the corners of the ring results in stronger interface coupling leading to higher blocking temperatures in the ring structure compared to the continuous film of the same film composition. At low temperature, the competition between unidirectional anisotropy and configurational anisotropy results in the formation of large domains at the corners of the ring, which results in lower values of exchange bias in the ring as compared to the continuous film. The effect of cooling field direction was also studied. We observed that the magnitude of bias obtained for negative field cooling direction is larger than that obtained for positive field cooling direction with sweeping field always starting from negative saturation. This observation has been ascribed to the dominance of FM domain magnetization determined by the external magnetic field over the cooling field which defines the AFM-FM interface coupling.
Modeling on domain switching in ferroelectric ceramics near the morphotropic phase boundary
Authors: Li F. X. , Li Y. W.
Published: June 2009

In this paper, domain switching in ferroelectric ceramics near the morphotropic phase boundary (MPB), where tetragonal phase and rhombohedral phase coexist, is analyzed by a micromechanical model using an inverse-pole-figure (IPF) method. Charge screening effect in ferroelectric ceramics is taken into account, thus the depolarization field by polarization switching vanishes. The mechanical constraint caused by non-180° switching, however, cannot be neglected and is assumed to be proportional to the switching strain caused by non-180° domain switching with a factor β as the measure of the constrained level. Using the IPF method, the domain switching induced polarization and strain can be explicitly obtained via integrations over the unit spherical surface. Two limiting cases are studied in this paper, i.e., the energy barrier for the interphase non-180° domain switching is equal to or much larger than that for the in-phase non-180° switching. In the former case, it is found that domains always tend to switch to the rhombohedral phase especially when the constrained level is high, i.e., at a large value of β. If the mechanical constraint is neglected, i.e., β=0, the maximum achievable polarization and strain can be analytically obtained in this case. While in the latter case, interphase domain switching is suppressed, thus domain switching in MPB ceramics is only a superposition of independent in-phase domain switching in tetragonal ceramics and rhombohedral ceramics.
Threshold photoionization and density functional theory studies of bimetallic-carbide nanocrystals and fragments: Ta3ZrCy (y=–4)
Authors: Dryza V. , Metha G. F.
Published: June 2009

Gas-phase bimetallic tantalum-zirconium-carbide clusters are generated using a constructed double ablation cluster source. The Ta3ZrCy (y=0–4) clusters are examined by photoionization efficiency spectroscopy to extract experimental ionization energies (IEs). The IE trend for the Ta3ZrCy cluster series is reasonably similar to that of the Ta4Cy cluster series [V. Dryza et al., J. Phys. Chem. A 109, 11180 (2005)], although the IE reductions upon carbon addition are greater for the former. Complementary density functional theory calculations are performed for the various isomers constructed by attaching carbon atoms to the different faces of the tetrahedral Ta3Zr cluster. The good agreement between the experimental IE trend and that calculated for these isomers support a 2×2×2 face centered cubic nanocrystal structure for Ta4ZrC4 and nanocrystal fragment structures for the smaller clusters.
NIF unconverted light and its influence on DANTE measurements
Authors: Girard Frederic , Suter Larry , Landen Otto , Munro Dave , Regan Sean , Kline John
Published: June 2009

NIF laser facility produces 1053 nm light and a fundamental requirement for NIF is to give up to 1.8 MJ of 351 nm light for target physics experiments. The 351 nm light is provided by frequency tripling the 1053 nm light in nonlinear crystals in the final optics assembly, just before the laser light enters the target chamber. Since this tripling process is not 100% efficient, unconverted light from the conversion process also enters the chamber. This unconverted light does not directly hit the target but it can strike target support structures at average intensities of few TW/cm2 where it can generate unwanted, background soft x-rays that are measured by the soft x-ray diagnostic DANTE installed on the NIF target chamber. This diagnostic quantifies the x-radiation intensity inside the hohlraum by measuring the x-ray flux coming from the target’s laser entrance hole. Due to its centimeter wide field of view, it integrates x-ray emission from both the flux exiting a hohlraum laser entrance hole and from the target support structure irradiated by residual 1ω and 2ω unconverted light. This work gives quantitative evaluations of the unconverted light for the first time and the effects on DANTE measurements for the future NIF tuning experiment called “Shock timing.” Emission spectra are significantly modified leading to an overestimation of radiative temperature during the foot of the laser pulse since background x-rays are predominant in first two DANTE channel measurements. Mitigations of these effects by coating silicon paddle with plastic, using a smaller collimator to reduce DANTE field of view or eliminating DANTE channels in the analysis have been investigated.
Near-infrared photon time-of-flight spectroscopy of turbid materials up to 1400 nm
Authors: Svensson Tomas , Alerstam Erik , Khoptyar Dmitry , Johansson Jonas , Folestad Staffan , Andersson-Engels Stefan
Published: June 2009

Photon time-of-flight spectroscopy (PTOFS) is a powerful tool for analysis of turbid materials. We have constructed a time-of-flight spectrometer based on a supercontinuum fiber laser, acousto-optical tunable filtering, and an InP/InGaAsP microchannel plate photomultiplier tube. The system is capable of performing PTOFS up to 1400 nm, and thus covers an important region for vibrational spectroscopy of solid samples. The development significantly increases the applicability of PTOFS for analysis of chemical content and physical properties of turbid media. The great value of the proposed approach is illustrated by revealing the distinct absorption features of turbid epoxy resin. Promising future applications of the approach are discussed, including quantitative assessment of pharmaceuticals, powder analysis, and calibration-free near-infrared spectroscopy.
The dynamics of the H2+CO+ reaction on an interpolated potential energy surface
Authors: Ramazani Shapour , Frankcombe Terry J. , Andersson Stefan , Collins Michael A.
Published: June 2009

A potential energy surface that describes the title reaction has been constructed by interpolation of ab initio data. Classical trajectory studies on this surface show that the total reaction rate is close to that predicted by a Langevin model, although the mechanism is more complicated than simple ion-molecule capture. Only the HCO++H product is observed classically. An estimate of the magnitude of rotational inelastic scattering is also reported.
Fluorescence diffuse optical tomography using upconverting nanoparticles
Authors: Xu Can T. , Axelsson Johan , Andersson-Engels Stefan
Published: June 2009

Fluorescence diffuse optical tomography (FDOT) can provide important information in biomedical studies. In this ill-posed problem, suppression of background tissue autofluorescence is of utmost importance. We report a method for autofluorescence-insensitive FDOT using nonlinear upconverting nanoparticles (NaYF4:Yb3+/Tm3+) in a tissue phantom under excitation intensities well below tissue-damage thresholds. Even with the intrinsic autofluorescence from the phantom only, the reconstruction of the nanoparticles is of much better quality than the reconstruction of a Stokes-shifting dye. In addition, the nonlinear power dependence leads to more confined reconstructions and may increase the resolution in FDOT.
Tunable nuclear polarization with external stationary fields in weakly coupled double quantum dots
Authors: Iñarrea Jesús , Lopez-Monis Carlos , Platero Gloria
Published: June 2009

Hyperfine interaction in double quantum dots releases spin blockade allowing the flux of electronic current. This interaction gives rise to a feedback mechanism between the spins of the electrons transported through the device and nuclei spins. In this letter, we analyze the role played by an external dc voltage in the dynamical nuclear polarization induced in a double quantum dot by hyperfine interaction. Accordingly, we show that the nuclear polarization in the quantum dots can be tuned by a source-drain external voltage and an external magnetic field.
Tunable ultraviolet emission of ZnO quantum dots in transparent poly(methyl methacrylate)
Authors: Sun Dazhi , Sue Hung-Jue
Published: June 2009

We report experimental results on tuning ultraviolet (UV) emissions of colloidal ZnO quantum dots (QDs) with uniform size in poly(methyl methacrylate) (PMMA) through controlling their dispersion. Instead of using organic ligands, exfoliated nanoplatelets were utilized as an inorganic dispersant to achieve controlled aggregate sizes of ZnO QDs in PMMA. The polymer nanocomposites are highly transparent in the visible range and readily exhibit blueshifted UV luminescence as the aggregate size of ZnO QDs reduces. The mechanisms responsible for the observed dispersion-dependent UV emissions are also described. The above approach presents an alternative way to design inorganic/organic hybrids with desired physical properties.
Reversible pyroelectric response in Pb0.955La0.03(Zr0.42Sn0.40Ti0.18)O3 ceramics near its phase transition
Authors: Zhang Hongling , Chen Xuefeng , Cao Fei , Wang Genshui , Dong Xianlin , Gu Yan , Liu Yusheng
Published: June 2009

Phase transition and pyroelectric behaviors of Pb0.955La0.03(Zr0.42Sn0.40Ti0.18)O3 (PLZST) ceramics were investigated as functions of temperature and electric field. Pyroelectric coefficient about 160×10−8 C cm−2 K−1 is detected at the electric-field-induce ferroelectric (FEIN) to antiferroelectric phase transition for the poled samples. Reversible pyroelectric response with a pyroelectric coefficient maximum about 50×10−8 C cm−2 K−1 is obtained when a dc bias is applied on the depoled sample simultaneously.
Silicon carbide nanostructures: A tight binding approach
Authors: Patrick Anthony D. , Dong Xiao , Allison Thomas C. , Blaisten-Barojas Estela
Published: June 2009

A tight-binding model Hamiltonian is newly parametrized for silicon carbide based on fits to a database of energy points calculated within the density functional theory approach of the electronic energy surfaces of nanoclusters and the total energy of bulk 3C and 2H polytypes at different densities. This TB model includes s and p angular momentum symmetries with nonorthogonal atomic basis functions. With the aid of the new TB model, minima of silicon carbide cagelike clusters, nanotubes, ring-shaped ribbons, and nanowires are predicted. Energetics, structure, growth sequences, and stability patterns are reported for the nanoclusters and nanotubes. The band structure of SiC nanotubes and nanowires indicates that the band gap of the nanotubes ranges from 0.57 to 2.38 eV depending on the chirality, demonstrating that these nanotubes are semiconductors or insulators. One type of nanowire is metallic, another type is semiconductor, and the rest are insulators.
High performance metal-insulator-metal capacitor using a SrTiO3/ZrO2 bilayer
Authors: Jorel C. , Vallée C. , Gonon P. , Gourvest E. , Dubarry C. , Defay E.
Published: June 2009

Future integration of metal-insulator-metal capacitors requires devices with high capacitance density and low quadratic voltage coefficient of capacitance (α). A major problem is that the increase in capacitance density is usually accompanied by increased voltage nonlinearities. By combining two high-k materials with opposite α, it is demonstrated that it is possible to obtain capacitors with both high capacitance density and minimal nonlinearity. A SrTiO3/ZrO2 bilayer was used to elaborate capacitors displaying a voltage coefficient of −60 ppm/V2 associated with a density of 11.5 fF/μm2. These devices constitute excellent candidates for the next generation of metal-insulator-metal capacitors.
Single-crystal-like, c-axis oriented BaTiO3 thin films with high-performance on flexible metal templates for ferroelectric applications
Authors: Shin Junsoo , Goyal Amit , Jesse Stephen , Kim Dae Ho
Published: June 2009

Epitaxial, c-axis oriented BaTiO3 thin films were deposited using pulsed laser ablation on flexible, polycrystalline Ni alloy tape with biaxially textured oxide buffer multilayers. The high quality of epitaxial BaTiO3 thin films with P4mm group symmetry was confirmed by x-ray diffraction. The microscopic ferroelectric domain structure and the piezoelectric domain switching in these films were confirmed via spatially resolved piezoresponse mapping and local hysteresis loops. Macroscopic measurements demonstrate that the films have well-saturated hysteresis loops with a high remanent polarization of ∼11.5 μC/cm2. Such high-quality, single-crystal-like BaTiO3 films on low-cost, polycrystalline, flexible Ni alloy substrates are attractive for applications in flexible lead-free ferroelectric devices.
Method to measure the viscosity of nanometer liquid films from the surface fluctuations
Authors: Yang Zhaohui , Lam Chi-Hang , DiMasi Elaine , Bouet Nathalie , Jordan-Sweet Jean , Tsui Ophelia K. C.
Published: June 2009

We describe a method to measure the viscosity of polystyrene liquid films with thicknesses ∼5 and ∼80 nm spin-cast on oxide-coated silicon. In this method, temporal evolution of the film surface is monitored and modeled according to the dynamics of the surface capillary waves. Viscosities obtained from the ∼80 nm films display an excellent agreement with those of the bulk polymer, but those from the ∼5 nm films are up to 106 times reduced. By modeling the data to the Vogel–Fulcher–Tammann relation, we find that the observations are consistent with the thickness dependence of the glass transition temperature previously reported of these films.