bluuebunny/crossref_metadata_2025 huggingface dataset:
Origin of olivine at Copernicus
Authors: Pieters Carle M. , Wilhelms Don E.
Published: December 2012

The central peaks of Copernicus are among the few lunar areas where near‐infrared telescopic reflectance spectra indicate extensive exposures of olivine. Other parts of Copernicus crater and ejecta, which were derived from highland units in the upper parts Of the target site, contain only low‐Ca pyroxene as a mafic mineral. The exposure of compositionally distinct layers including the presence of extensive olivine may result from penetration to an anomalously deep layer of the crust or to the lunar mantle. We suggest that the Procellarum basin and the younger, superposed Insularum basin have provided access to these normally deep‐seated crustal or mantle materials by thinning the upper crustal material early in lunar history. The occurrences of olivine in portions of the compositionally heterogeneous Aristarchus Region, in a related geologic setting, may be due to the same sequence of early events.
A transient heating event in the history of a highlands troctolite from Apollo 12 soil 12033
Authors: Marvin Ursula B. , Walker David
Published: December 2012

A 1.5 mm clast of a highlands troctolite attached to a glassy, alkali‐rich soil breccia was identified in a thin section of 1‐2 mm particles from Apollo 12 soil sample 12033. The troctolite consists of euhedral olivines (Fo89) in a groundmass of granulitic plagioclase (An95); each olivine grain is rimmed by a thin selvage of olivine‐plagioclase glass containing vesicles and minute crystallites of spinel, olivine, and plagioclase. This unique texture records a complex history, beginning with the formation of the troctolite as a plutonic cumulate, followed by subsolidus metamorphism, partial remelting, vesculation, crystallite growth, and quenching. Experimental runs on plagioclase‐olivine melting rates show that, at temperatures above incipient melting, the grain‐boundary selvages in the lunar troctolite would have formed very rapidly (in less than about 10 min). Preservation of selvage glass required rapid cooling. The troctolite was subject to a heat pulse, most likely accompanying an impact event. The same event, or more probably a later one, welded the troctolite to the soil breccia. Inasmuch as this particle was found on Oceanus Procellarum at a site crossed by a ray from Copernicus, and because olivine has been identified by remote sensing experiments as the dominant mafic mineral in the central peak of Copernicus, we suggest that the troctolite is a fragment of Copernicus ejecta.
Thermal structure of the accreting Earth
Authors: Turcotte D. L. , Pflugrath J. C.
Published: December 2012

The energy associated with the accretion of the earth and the segregation of the core is more than sufficient to melt the entire earth. In order to understand the thermal evolution of the early earth it is necessary to study the relevant heat transfer mechanisms. In this paper we postulate the existence of a global magma ocean and carry out calculations of the heat flux through it in order to determine its depth. In the solid mantle heat is transferred by the upward migration of magma. This magma supplies the magma ocean. The increase in the mantle liquidus with depth (pressure) is the dominant effect influencing heat transfer through the magma ocean. We find that a magma ocean with a depth of the order of 20 km would have existed as the earth accreted. We conclude that the core segregated and an atmosphere was formed during accretion.
The parental magma for some rocks from the Norite 1 subzone of the Stillwater Complex: A lunar analog study
Authors: Ryder G. , Spettel B.
Published: December 2012

The interpretation of single lunar highlands igneous samples is hindered not only by their brecciation but also by a lack of similar intensive work on terrestrial plutonic rocks. Terrestrial studies of cumulate rocks are more extensive and have a well‐developed stratigraphic context. In an attempt to establish how much can be learned about the parent magma from single plutonic hand samples, single samples from three successive homogeneous but contrasting layers (anorthosite, anorthositic norite, norite) in the Stillwater Complex Norite 1 subzone were subjected to detailed petrographic and major and trace element chemical analyses. The chemical data show that although the calculated parent magma for each layer is similar, a model of liquidus phases plus trapped magma model is not simultaneously quite consistent with petrography and chemistry. Further, calculated Eu anomalies and the Fe content of the plagioclases provide evidence that the oxidation of the magma was different for each layer. Such oxidation changes can explain qualitatively the Mg/Fe variations otherwise attributed to trapped liquid. However, it would appear that a reasonable estimate of the parent composition can be made even for single hand samples, such as lunar plutonic highlands rocks. There are uncertainties, and a better understanding of crystallization mechanisms for basic plutonic rocks is needed. Without such understanding lunar samples can never be fully interpreted. The calculated parent for the Stillwater Complex Norite 1 subzone rocks considered is chemically similar to some primitive continental tholeiites, except for its high normative orthopyroxene and negative Eu anomaly, both of which are major differences. Published data show that the Eu anomaly existed in parental magmas even for the lower ultramafic zone, and that most REE data are consistent with common or closely related parents for all rocks of the Stillwater. At least, radically different magmas for different parts of the intrusion do not seem likely.
Petrology of types 4–6 carbonaceous chondrites
Authors: Scott Edward R. D. , Taylor Jeffrey
Published: December 2012

We have studied the petrology of three type 4 carbonaceous chondrites, Coolidge, Karoonda, and Pecora Escarpment 82500, which was previously classified as an LL6 chondrite, and compared them to published descriptions of the other known metamorphosed C chondrites, Yamato 6903 and Mulga (west). All except Coolidge have abundant matrix, typically 80 vol %, composed largely of homogeneous olivine, Fa 29–33, and surprisingly heterogeneous plagioclase, mostly An 20–75. Their opaque mineralogy indicates high oxygen fugacities during metamorphism: metallic Fe,Ni and troilite are rare, and magnetite and pentlandite are abundant with accessory pyrrhotite, chalcopyrite, and pyrite. Possibly because of a lower matrix abundance, Coolidge has more reduced minerals: metallic Fe,Ni and olivine with Fa 14. The properties of all C4–6 chondrites appear to be consistent with an origin by metamorphism of C3‐like precursors by processes analogous to those operating in ordinary chondrite parent bodies or planetesimals. However, type 4–6 material was not well mixed with type 3 material in the CV3 parent body, as it was in the ordinary chondrite parent bodies. Conceivably, C4–6 chondrites come from one or more separate parent bodies.
NRM directions around a centimetersized dark inclusion in Allende
Authors: Sugiura N. , Strangway D. W.
Published: December 2012

The natural remanent magnetization (NRM) carried by a centimeter‐sized dark inclusion, the surrounding matrix, and individual chondrules in Allende was measured to determine the magnetic history of the meteorite. It was found that before demagnetization all the bulk specimens (matrix and the inclusion) have roughly the same NRM directions. There are, however, significant differences in direction between the inclusion and three separate regions of the surrounding matrix. It was also found that in one region the matrix had a systematic variation in NRM directions. The NRM directions of individual chondrules are scattered but they are grouped in one quadrant, with a mean direction different from that of the matrix. Stepwise thermal demagnetization revealed that all specimens carry two components of magnetization. The lower temperature component appears to be carried by pyrrhotite. The directions of the high‐temperature component of NRM in both chondrules and bulk matrix specimens are almost randomly scattered. It is difficult to explain all the observed features of the NRM, but the following conditions appear to be required: (1) Chondrules and the inclusion were magnetized before accretion of Allende, hence they carry the record of early solar system magnetic fields. (2) The whole rock was partially remagnetized after accretion by a thermochemical event, thus carrying a record of a magnetic field that was present during or after accretion. (3) The bulk matrix, the inclusion, and some of the chondrules have rotated (or were deformed) after they were remagnetized.
Iron‐montmorillonite: A spectral analog of Martian soil
Authors: Banin A. , Margulies L. , Chen Y.
Published: December 2012

Light absorption and reflectance by smectite clays containing various adsorbed ions were measured in the UV, VIS, and NIR ranges and compared to Martian dust and surface soil spectra. Structural iron in the octahedral sheet of smectites is responsible for a characteristic absorption feature in the UV at 240–260 nm, resulting from an O2−—Fe3+ charge transfer that is similar to one observed in the Martian spectrum. Adsorbed iron affects, via crystal field absorptions, the reflectance of montmorillonite in the VIS and NIR (to 1.3 μm), causing stronger absorption and higher opacity in the wavelength range 0.4–0.6 μm, without developing any specific pronounced absorption feature. In both general appearance and presence of, or lack of, spectral features, the iron‐montmorillonite reflectance spectra in the VIS and NIR are similar to the Martian spectra. At present, however, spectral similarity cannot be used as the sole criterion for constraining Martian mineralogy since several other minerals, other than Fe‐smectites, show sufficient similitude to the Martian spectra; other properties have to be explored and combined to obtain a definitive identification.
Dark halo craters and the thickness of grooved terrain on Ganymede
Authors: Schenk Paul M. , McKinnon William B.
Published: December 2012

Dark halo craters in grooved terrain on Ganymede represent potential probes of the subsurface geology. These craters are surrounded by a broad, diffuse, low albedo annulus, or halo. Halo radius is linearly proportional to crater radius, indicating that the halo is related to the continuous ejecta deposit of the crater and is not removed by natural aging processes, such as regolith development and exposure to the space environment. The halos have orange/violet albedo ratios that are intermediate between ratios associated with grooved terrain and cratered terrain. We propose that halos result from the incorporation of cratered terrain material into crater ejecta. In Uruk Sulcus, only craters greater than ∼12 km in diameter have halos, indicating that the cratered terrain material there forms a stratigraphic horizon, buried at depth in the grooved terrain, into which only larger craters can excavate. This depth can be calculated from the transition diameter by reconstructing the transient crater. We calculate a depth of excavation, corresponding to the depth of burial of cratered terrain, of 1.0 to 1.6 km. This shallow burial is inconsistent with deep subsidence and burial, stoping into the interior, or lateral spreading apart of ancient cratered terrain units, but is consistent with a filled graben model for grooved terrain, where relatively clean ice has been emplaced over downdropped blocks of cratered terrain.
“Globus Symptoms”: A Rare Case of Giant Osteochondroma of the Axis Treated with High Cervical Extrapharyngeal Approach
Authors: Wong Ken , Bhagat Shaishav , Clibbon Jonothan , Rai A. S.
Published: December 2012

Background

Osteochondroma is the most common primary bone tumor, composing 35% of benign bone tumors and 9% of all bone tumors; 1.3 to 4.1% of all osteochondromas originate from the spine. A rare differential diagnosis for globus symptoms is an osteochondroma originating from the anterior surface of the axis. We describe a rare case of osteochondroma of the dens resulting in “globus symptoms” (the subjective sensation of a mass in the throat) treated with excision via the high cervical extrapharyngeal approach.

Purpose

To discuss the surgical management of this problem, with an emphasis on surgical approach used. The clinical history, examination, and investigations are presented and illustrated, along with clinical patient outcome.

Study Design/Setting

This article is a case report of a patient treated at the Department of Trauma and Orthopaedics in an active university teaching hospital.

Methods

Case presentation. For the discussion, we used handpicked articles, as well as MEDLINE and PubMed database searches with the keywords “C2,” “dens,” “osteochondroma,” “globus,” “extrapharyngeal approach.”

Results

Uncomplicated procedure. Histological analysis confirmed a benign osteochondroma with no evidence of malignancy. The patient underwent an uncomplicated postoperative recovery and was discharged 24 hours after surgery, fully ambulatory and eating and drinking well.

Conclusions

The high cervical retropharyngeal approach is safe and reproducible for the excision of osteochondromas or osteophytes of the upper cervical spine.
Rabi and Larmor nuclear quadrupole double resonance of spin-1 nuclei
Authors: Prescott D. W. , Malone M. W. , Douglass S. P. , Sauer K. L.
Published: December 2012

We demonstrate the creation of two novel double-resonance conditions between spin-1 and spin-1/2 nuclei in a crystalline solid. Using a magnetic field oscillating at the spin-1/2 Larmor frequency, the nuclear quadrupole resonance (NQR) frequency is matched to the Rabi or Rabi plus Larmor frequency, as opposed to the Larmor frequency as is conventionally done. We derive expressions for the cross-polarization rate for all three conditions in terms of the relevant secular dipolar Hamiltonian, and demonstrate with these expressions how to measure the strength of the heterogenous dipolar coupling using only low magnetic fields. In addition, the combination of different resonance conditions permits the measurement of the spin-1/2 angular momentum vector using spin-1 NQR, opening up an alternate modality for the monitoring of low-field nuclear magnetic resonance. We use ammonium nitrate to explore these resonance conditions, and furthermore use the oscillating field to increase the signal-to-noise ratio per time by a factor of 3.5 for NQR detection of this substance.
Molecular elimination of Br2 in photodissociation of CH2BrC(O)Br at 248 nm using cavity ring-down absorption spectroscopy
Authors: Fan He , Tsai Po-Yu , Lin King-Chuen , Lin Cheng-Wei , Yan Chi-Yu , Yang Shu-Wei , Chang A. H. H.
Published: December 2012

The primary elimination channel of bromine molecule in one-photon dissociation of CH2BrC(O)Br at 248 nm is investigated using cavity ring-down absorption spectroscopy. By means of spectral simulation, the ratio of nascent vibrational population in v = 0, 1, and 2 levels is evaluated to be 1:(0.5 ± 0.1):(0.2 ± 0.1), corresponding to a Boltzmann vibrational temperature of 581 ± 45 K. The quantum yield of the ground state Br2 elimination reaction is determined to be 0.24 ± 0.08. With the aid of ab initio potential energy calculations, the obtained Br2 fragments are anticipated to dissociate on the electronic ground state, yielding vibrationally hot Br2 products. The temperature-dependence measurements support the proposed pathway via internal conversion. For comparison, the Br2 yields are obtained analogously from CH3CHBrC(O)Br and (CH3)2CBrC(O)Br to be 0.03 and 0.06, respectively. The trend of Br2 yields among the three compounds is consistent with the branching ratio evaluation by Rice-Ramsperger-Kassel-Marcus method. However, the latter result for each molecule is smaller by an order of magnitude than the yield findings. A non-statistical pathway so-called roaming process might be an alternative to the Br2 production, and its contribution might account for the underestimate of the branching ratio calculations.
Multicolor in vivo brain imaging with a microscope-coupled fiber-bundle microprobe
Authors: Doronina-Amitonova Lyubov V. , Fedotov Il'ya V. , Efimova Olga , Chernysheva Maria , Fedotov Andrei B. , Anokhin Konstantin V. , Zheltikov Aleksei M.
Published: December 2012

A fiber-bundle microprobe coupled to a confocal optical microscope is shown to enable multicolor in vivo fluorescence brain imaging. A bundle of several thousands of 2.4-μm-diameter optical fibers is employed to deliver multiwavelength laser excitation radiation and to transmit multicolor images from hippocampus tissues in living transgenic mice by picking up a multiplex fluorescent response from green fluorescent protein, nucleic acid counterstains, and neuron tracers.
Organic solvents as gate media for thin-film transistors
Authors: Al Naim Abdullah F. , Grell Martin
Published: December 2012

Here, we show that some organic solvents can act as electric double layer (EDL) gate media for thin film transistors (TFTs), in a similar way to solid electrolytes, ionic liquids, and water. The ability to act as gate medium is a property of the solvent, not a property of the semiconductor used in the TFT. Only solvents that are fully miscible with water can act as a gate media. However, the ability to undergo autoprotolysis is not an essential property of a gate medium. The most likely explanation for the ability of water-miscible solvents to act as EDL gate media is the inevitable presence of trace amounts of dissolved salts. Because of its large electrochemical window, and aprotic character, acetonitrile is particularly attractive as an alternative gate medium.
Effect of silver incorporation in phase formation and band gap tuning of tungsten oxide thin films
Authors: Jolly Bose R. , Vinod Kumar R. , Sudheer S. K. , Reddy V. R. , Ganesan V. , Mahadevan Pillai V. P.
Published: December 2012

Silver incorporated tungsten oxide thin films are prepared by RF magnetron sputtering technique. The effect of silver incorporation in micro structure evolution, phase enhancement, band gap tuning and other optical properties are investigated using techniques such as x-ray diffraction, micro-Raman spectroscopy, atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and UV-Visible spectroscopy. Effect of silver addition in phase formation and band gap tuning of tungsten oxide thin films are investigated. It is found that the texturing and phase formation improves with enhancement in silver content. It is also found that as the silver incorporation enhances the thickness of the films increases at the same time the strain in the film decreases. Even without annealing the desired phase can be achieved by doping with silver. A broad band centered at the wavelength 437 nm is observed in the absorption spectra of tungsten oxide films of higher silver incorporation and this can be attributed to surface plasmon resonance of silver atoms present in the tungsten oxide matrix. The transmittance of the films is decreased with increase in silver content which can be due to increase in film thickness, enhancement of scattering, and absorption of light caused by the increase of grain size, surface roughness and porosity of films and enhanced absorption due to surface plasmon resonance of silver. It is found that silver can act as the seed for the growth of tungsten oxide grains and found that the grain size increases with silver content which in turn decreases the band gap of tungsten oxide from 3.14 eV to 2.70 eV.
Characterization of temporal and spatial distribution of hydrogen gas density in capillary tubes for laser-plasma experiments
Authors: Ju J. , Cros B.
Published: December 2012

Measurements of the time evolution of neutral hydrogen gas filling capillary tubes were performed by interferometry. Time-resolved gas density evolution was observed by following the temporal variation of the interference pattern, while the spatial distribution of gas in the stationary state was obtained by numerical fluid simulation. It was found that for a 178 μm diameter and 30 mm long capillary tube, the gas flow reaches a stable state at around t=34 ms regardless of the value of the reservoir pressure in the range of 100–500 mbar. The gas density filling the capillary tube is measured to be 81±3% of the reservoir density; the density drop is attributed to losses along the filling line and gas leaks from the capillary in the background vacuum.
Influence of the A/B nonstoichiometry, composition modifiers, and preparation methods on properties of Li- and Ta-modified (K,Na)NbO3 ceramics
Authors: Morozov Maxim I. , Hoffmann Michael J. , Benkert Katrin , Schuh Carsten
Published: December 2012

Properties of Li- and Ta- modified (K,Na)NbO3 piezoceramics with the base composition near the orthorhombic-tetragonal phase boundary have been investigated with respect to variation of temperature, stoichiometry, compositional homogeneity, atmosphere of thermal treatment, and dopants (Ba, Mn). Although the influence of the most of the abovementioned factors has already been reported in the literature, the paper focuses on several aspects of the composition—property relationships that still remain controversial or poorly elucidated. In particular, we show that improvement of compositional homogeniety in these ceramics emphasizes the instability of piezoelectric response with respect to variation of temperature in the vicinity of the orthorhombic-tetragonal phase transition. Ba dopant is shown to suppress conductivity in ceramics sintered in air, though it makes conductivity more sensitive to variation of the oxygen partial pressure. Mn dopant is shown to suppress conductivity and strongly reduce the influence of the oxygen partial pressure on conductivity of the ceramics. Finally, we show that chemical modifications to the ceramic composition, such as Mn dopant or variation of nonstoichiometry affect the piezoelectric response mainly by the shift of the orthorhombic-tetragonal phase transition temperature.
Metastable resistivity states and conductivity fluctuations in low-doped La1−xCaxMnO3 manganite single crystals
Authors: Dolgin B. , Belogolovskii M. , Wu X. D. , Markovich V. , Jung G.
Published: December 2012

Conductivity noise in dc current biased La0.82Ca0.18MnO3 single crystals has been investigated in different metastable resistivity states enforced by applying voltage pulses to the sample at low temperatures. Noise measured in all investigated resistivity states is of 1/f-type and its intensity at high temperatures and low dc bias scales as a square of the bias. At liquid nitrogen temperatures for under bias exceeding a threshold value, the behavior of the noise deviates from above quasi-equilibrium modulation noise and depends in a non monotonic way on applied bias. The bias range of nonequilibrium 1/f noise coincides with the range at which the conductance increases linearly with bias voltage. This feature is attributed to a broad continuity of states enabling indirect inelastic tunneling across intrinsic tunnel junctions. The nonequilibrium noise has been ascribed to indirect intrinsic tunneling mechanism while resistivity changes in metastable states to variations in the energy landscape for charge carriers introduced by microcracks created by the pulse procedures employed.
Reduction of the piezoelectric performance in lead-free (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 piezoceramics under uniaxial compressive stress
Authors: Ehmke Matthias C. , Daniels John , Glaum Julia , Hoffman Mark , Blendell John E. , Bowman Keith J.
Published: December 2012

The effect of a uniaxial compressive stress on the properties of BZT-BCT samples across the morphotropic phase boundary (MPB) is investigated using direct piezoelectric coefficient measurements. In contrast to many lead zirconate titanate compositions, the piezoelectric coefficient decreases monotonically with increasing stress and does not show an initial increase or plateau. Electrically softer rhombohedral and MPB compositions are found to be more susceptible to a decrease in piezoelectric coefficient under an increasing pre-stress than tetragonal compositions. Depoling due to ferroelastic domain switching alone, as observed by x-ray diffraction, does not explain this reduction, but instead a decreasing domain wall density is proposed to be responsible for reduced piezoelectric coefficients under increasing compressive stress. The relaxation of the piezoelectric response after complete unloading supports this proposed mechanism.
Influence of a superficial field of residual stress on the propagation of surface waves—Applied to the estimation of the depth of the superficial stressed zone
Authors: Duquennoy Marc , Ouaftouh Mohammadi , Deboucq Julien , Lefebvre Jean-Etienne , Jenot Frédéric , Ourak Mohamed
Published: December 2012

In this study, we were interested in the dispersion of surface waves caused by the presence of a micrometric field of residual stress on the surface of an amorphous medium. We have shown that in relation to surface waves, a stressed structure like this is comparable to a layer on substrate type structure. The design and implementation of SAW-IDT MEMS sensors enabled quasi-monochromatic Rayleigh-type surface waves to be generated and the dispersion phenomenon to be studied over a wide range of frequencies for different superficial fields of residual stress. The thicknesses of the stressed cortical zones were estimated with good accuracy using an inverse method.
A fast real time measurement system to track in and out of plane optical retardation/ birefringence, true stress, and true strain during biaxial stretching of polymer films
Authors: Cakmak M. , Hassan M. , Unsal E. , Martins C.
Published: December 2012

An instrumented and highly integrated biaxial stretching system was designed and constructed to obtain true stress, true strain, and optical behavior of polymeric films during biaxial stretching. With programmable drive motors, any form of temporally varying biaxial deformation profiles, including linear, exponential, logarithmic as well as cyclic, can be applied to a square-shaped films. This machine allows the investigation of mechano-optical behavior of films under profiles captured in industrial processes. To overcome the edge effects, the samples are painted with a dot pattern that is imaged using a high speed video capture system. This system accurately determines the locations of the each dot matrix in subsequent images acquired and calculates the true strains in both directions. The in-plane optical retardation is determined using spectral birefringence method that uses polarized white light and optical spectrometer in the optical train. This is carried out automatically at less than 10 nm in retardation resolution with the light beam passing through the symmetry center of the sample. Out of plane retardation is measured with an identical optical train tilted 45° to the plane of the film with its light beam going through the same spot on the sample as 0° beam. The true stress and birefringences are calculated with the determined instantaneous thickness of the film. With this system, the stress optical behavior of PET's is determined up to very large deformation levels at moderate to high deformation rates. Beyond the initial linear stress optical behavior, these films exhibit sudden positive deviation from linearity and this start of nonlinearity was directly associated with the stress induced crystallization.
The quantum Lane-Emden-type Kanai-Caldirola oscillators
Authors: Bessa V. H. L. , Guedes I.
Published: December 2012

We obtain the exact wave functions of two Lane-Emden-type Kanai-Caldirola (LE-KC) oscillators by using the dynamical invariant method. To do so, we analytically solve the respective Milne-Pinney equation for each oscillator. We also calculate the uncertainty product, the transition probability and the quantum-mechanical energy expectation value for each oscillator. We compare the results with those of the well-known KC oscillator. The quantum-mechanical energy expectation value of the KC oscillator goes to zero faster than that of the LE-KC oscillators, indicating that the KC system is more damped than the LE-KC ones.
Spectroscopy of the $\tilde A$Ã state of NO–alkane complexes (alkane = methane, ethane, propane, and n-butane)
Authors: Tamé-Reyes Victor M. , Gardner Adrian M. , Harris Joe P. , McDaniel Jodie , Wright Timothy G.
Published: December 2012

We have recorded (1+1) resonance-enhanced multiphoton ionization spectra of complexes formed between NO and the alkanes: CH4, C2H6, C3H8, and n-C4H10. The spectra correspond to the $\tilde A$Ã ← $\tilde X$X̃ transition, which is a NO-localized 3s ← 2pπ* transition. In line with previous work, the spectrum for NO–CH4 has well-defined structure, but this is only partially resolved for the other complexes. The spectra recorded in the NO+–alkane mass channels all show a slowly rising onset, followed by a sharp offset, which is associated with dissociation of NO–alkane, from which binding energies in the $\tilde X$X̃ and $\tilde A$Ã states are deduced. Beyond this sharp offset, there is a further rise in signal, which is attributed to fragmentation of higher complexes, NO–(alkane)n. Analysis of these features allows binding energies for (NO–alkane) ··· alkane to be estimated, and these suggest that in the NO–(alkane)2 complexes, the second alkane molecule is bound to the first, rather than to NO. Calculated structures for the 1:1 complexes are reported, as well as binding energies.
Solvated electron yields in liquid and supercritical ammonia—A statistical mechanical treatment
Authors: Schiller Robert , Horváth Ákos
Published: December 2012

Earlier the geminate recombination of ions and solvated electrons, produced by ionizing radiation or laser light, was theoretically treated by a model which consisted of a Rydberg atom interacting with the thermodynamic fluctuations of the medium [R. Schiller, J. Chem. Phys. 92, 5527 (1990)]10.1063/1.458510. The theory was applied to liquid-to-supercritical water [R. Schiller and Á. Horváth, J. Chem. Phys. 135, 084510 (2011)]10.1063/1.3628677. Now it is compared with recent experiments performed on liquid-to-supercritical ammonia [J. Urbanek, A. Dahmen, J. Torres-Alacan, P. Königshoven, J. Lindner, and P. Vöhringer, J. Phys. Chem. B 116, 2223 (2012)]10.1021/jp211725r. The agreement between theory and experiment seems to be reasonable. The treatment is critically assessed.
Single molecule diffusion in critical lipid bilayers
Authors: McConnell Harden
Published: December 2012

Time-dependent single molecule diffusion coefficients are discussed for a fluorescent probe molecule in lipid mixtures near a miscibility critical point. The calculations take advantage of the theoretical wave vector dependent composition diffusion coefficients obtained by Inaura and Fujitani [J. Phys. Soc. Jpn. 77, 114603 (2008)10.1143/JPSJ.77.114603]. It is suggested that the diffusion of the probe molecule reflects in part the time-dependent composition diffusion near a critical point. The calculations show a striking biphasic time-dependent diffusion that switches from a faster diffusion at short times to a slower diffusion at a time approximately equal to πξ2/D where ξ is the correlation length and D is the composition diffusion coefficient at the switch time. This biphasic diffusion should be readily detectable experimentally.
Vibrational dynamics of the ${\rm H}_5^+$H5+ and its isotopologues from multiconfiguration time-dependent Hartree calculations
Authors: Valdés Álvaro , Prosmiti Rita , Delgado-Barrio Gerardo
Published: December 2012

Full-dimensional multiconfiguration time-dependent Hartree (MCTDH) computations are reported for the vibrational states of the \documentclass[12pt]{minimal}\begin{document}${\rm H}_5^+$\end{document}H5+ and its H4D+, H3\documentclass[12pt]{minimal}\begin{document}${\rm D}_2^+$\end{document}D2+, H2\documentclass[12pt]{minimal}\begin{document}${\rm D}_3^+$\end{document}D3+, \documentclass[12pt]{minimal}\begin{document}${\rm HD}_4^+$\end{document} HD 4+, \documentclass[12pt]{minimal}\begin{document}${\rm D}_5^+$\end{document}D5+ isotopologues employing two recent analytical potential energy surfaces of Xie et al. [J. Chem. Phys. 122, 224307 (2005)10.1063/1.1927529] and Aguado et al. [J. Chem. Phys. 133, 024306 (2010)10.1063/1.3454658]. The potential energy operators are constructed using the n-mode representation adapted to a four-combined mode cluster expansion, including up to seven-dimensional grids, chosen adequately to take advantage in representing the MCTDH wavefunction. An error analysis is performed to quantify the convergence of the potential expansion to reproduce the reference surfaces at the energies of interest. An extensive analysis of the vibrational ground state properties of these isotopes and comparison with the reference diffusion Monte Carlo results by Acioli et al. [J. Chem. Phys. 128, 104318 (2008)10.1063/1.2838847] are presented. It is found that these systems are highly delocalized, interconverting between equivalent minima through rotation and internal proton transfer motions even at their vibrational ground state. Isotopic substitution affects the zero-point energy and structure, showing preference in the arrangements of the H and D within the mixed clusters, and the most stable conformers of each isotopomer are the ones with the H in the central position. Vibrational excited states are also computed and by comparing the energies and structures predicted from the two surfaces, the effect of the potential topology on them is discussed.
Electron-state engineering of bilayer graphene by ionic molecules
Authors: Thanh Cuong Nguyen , Otani Minoru , Okada Susumu
Published: December 2012

Based on the first-principles total-energy calculations, we demonstrate the possibility of controlling the band-gap and carrier type of bilayer graphene using ionic molecules. Our calculations suggest that bilayer graphene sandwiched by a pair of cation-anion molecules is a semiconductor with a moderate energy gap of 0.26 eV that is attributable to the strong local dipole field induced by the cation-anion pair. Furthermore, we can control the semiconducting carrier type—intrinsic, p-type, or n-type—of bilayer graphene sandwiched by ionic molecules by changing the cation-anion pair.
Characterization of InSb quantum wells with atomic layer deposited gate dielectrics
Authors: Uddin M. M. , Liu H. W. , Yang K. F. , Nagase K. , Mishima T. D. , Santos M. B. , Hirayama Y.
Published: December 2012

We report magnetotransport measurements of a gated InSb quantum well (QW) with high quality Al2O3 dielectrics (40 nm thick) grown by atomic layer deposition. The magnetoresistance data demonstrate a parallel conduction channel in the sample at zero gate voltage (Vg). A good interface between Al2O3 and the top InSb layer ensures that the parallel channel is depleted at negative Vg and the density of two-dimensional electrons in the QW is tuned by Vg with a large ratio of 6.5 × 1014 m−2 V−1 but saturates at large negative Vg. These findings are closely related to layer structures of the QW as suggested by self-consistent Schrödinger-Poisson simulation and two-carrier model.
Inverse melting in stressed fused silica
Authors: Bouchut Philippe
Published: December 2012

The emissive properties of proton implanted fused silica surfaces have been studied by laser beam annealing. When submitted to a high thermal step from a focused CO2 laser, an intense near infra-red thermoluminescence peak rises at a heating rate threshold. The in plane tensile stress relaxes and silica melts. We show that in the irreversible inverse melting of stressed fused silica, the protons exo-diffuse through internal modes coupling. The heat and mass transfer is one entropy flux whose dynamics are regulated by the mass transport. Inverse melting is the thermodynamic process that initiates the glass transition when heating.
Tandem photovoltaic cells formed in single fullerene films by impurity doping
Authors: Ishiyama Norihiro , Kubo Masayuki , Kaji Toshihiko , Hiramoto Masahiro
Published: December 2012

Tandem photovoltaic cells were formed in single fullerene films by doping with molybdenum oxide and cesium carbonate. A heavily doped n+p+-homojunction acted as an ohmic interlayer between the two pn-homojunction cells. The observed photovoltaic properties of the tandem cell were shown to be consistent with the energy band diagram mapped using a Kelvin probe.
Effects of external surface charges on the enhanced piezoelectric potential of ZnO and AlN nanowires and nanotubes
Authors: Min Kim Seong , Kim Hyeok , Nam Youngmin , Kim Sungjin
Published: December 2012

We theoretically investigate external surface charge effects on piezoelectric potential of ZnO and AlN nanowires (NWs) and nanotubes (NTs) under uniform compression. The free carrier depletion caused by negative surface charges via surface functionalization on vertically compressed ZnO and AlN NWs/NTs is simulated using finite element calculation; this indicates the enhancement of piezoelectric potential is due to the free carriers (electrons) being fully depleted at the critical surface charge density. Numerical simulations reveal that full coverage of surface charges surrounding the NTs increases the piezoelectric output potential exponentially within a relatively smaller range of charge density compared to the case of NWs for a typical donor concentration (∼1017 cm−3). The model can be used to design functional high-power semiconducting piezoelectric nanogenerators.
Use of biotinylated plasmid DNA as a surrogate for HSV DNA to identify proteins that repress or activate viral gene expression
Authors: Mallon Stephen , Wakim Bassam T. , Roizman Bernard
Published: December 2012

Significance

DNA introduced into cells by infection or transfection is immediately coated by repressive histones and repressors. Viruses have evolved mechanisms to derepress their genes. What we know of these events is based on ChIP analyses that help identify the proteins involved in these processes, provided their identity is suspected and reagents are available. We report a procedure that enables identification of proteins hitherto not linked to these processes, based on the observation that HSV derepresses both viral DNA and DNAs introduced concurrently by transfection by using the transfected DNA as the surrogate for viral DNA.
Mitogen-activated protein kinase phosphatase 2 regulates histone H3 phosphorylation via interaction with vaccinia-related kinase 1
Authors: Jeong Min-Woo , Kang Tae-Hong , Kim Wanil , Choi Yoon Ha , Kim Kyong-Tai
Published: December 2012

Mitogen-activated protein kinase phosphatase 2 (MKP2) is a member of the dual-specificity MKPs that regulate MAP kinase signaling. However, MKP2 functions are still largely unknown. In this study, we showed that MKP2 could regulate histone H3 phosphorylation under oxidative stress conditions. We found that MKP2 inhibited histone H3 phosphorylation by suppressing vaccinia-related kinase 1 (VRK1) activity. Moreover, this regulation was dependent on the selective interaction with VRK1, regardless of its phosphatase activity. The interaction between MKP2 and VRK1 mainly occurred in the chromatin, where histones are abundant. We also observed that the protein level of MKP2 and its interaction with histone H3 increased from G1 to M phase during the cell cycle, which is similar to the VRK1 profile. Furthermore, MKP2 specifically regulated the VRK1-mediated histone H3 phosphorylation at M phase. Taken together, these data suggest a novel function of MKP2 as a negative regulator of VRK1-mediated histone H3 phosphorylation.
Ancient ubiquitous protein-1 mediates sterol-induced ubiquitination of 3-hydroxy-3-methylglutaryl CoA reductase in lipid droplet–associated endoplasmic reticulum membranes
Authors: Jo Youngah , Hartman Isamu Z. , DeBose-Boyd Russell A.
Published: December 2012

Sterol-induced binding to Insigs in endoplasmic reticulum (ER) membranes triggers ubiquitination of the cholesterol biosynthetic enzyme 3-hydroxy-3-methylglutaryl CoA reductase. This ubiquitination, which is mediated by Insig-associated ubiquitin ligases gp78 and Trc8, is obligatory for extraction of reductase from lipid droplet–associated ER membranes into the cytosol for proteasome-mediated, ER-associated degradation (ERAD). In this study, we identify lipid droplet–associated, ancient, ubiquitous protein-1 (Aup1) as one of several proteins that copurify with gp78. RNA interference (RNAi) studies show that Aup1 recruits the ubiquitin-conjugating enzyme Ubc7 to lipid droplets and facilitates its binding to both gp78 and Trc8. The functional significance of these interactions is revealed by the observation that RNAi-mediated knockdown of Aup1 blunts sterol-accelerated ubiquitination of reductase, which appears to occur in lipid droplet–associated membranes and subsequent ERAD of the enzyme. In addition, Aup1 knockdown inhibits ERAD of Insig-1, another substrate for gp78, as well as that of membrane-bound precursor forms of sterol-regulatory, element-binding protein-1 and -2, transcription factors that modulate expression of genes encoding enzymes required for cholesterol synthesis. Considered together, these findings not only implicate a role for Aup1 in maintenance of intracellular cholesterol homeostasis, but they also highlight the close connections among ERAD, lipid droplets, and lipid droplet–associated proteins.
The dark knight falters
Authors: Mirabal N.
Published: December 2012

Tentative line emission at 111 and 129 GeV from 16 unassociated Fermi-LAT point sources has been reported recently by Su and Finkbeiner. Together with similar features seen by Fermi in a region near the Galactic Centre, the evidence has been interpreted as the spectral signature of dark matter annihilation or internal bremsstrahlung. Through a combination of supervised machine-learning algorithms and archival multiwavelength observations, we find that 14 out of the 16 unassociated sources showing that the line emission in the Su and Finkbeiner sample are most likely active galactic nuclei (AGN). Based on this new evidence, one must widen the range of possible solutions for the 100–140 GeV excess to include a very distinct astrophysical explanation. While we cannot rule out a dark matter origin for the line emission in the Galactic Centre, we posit that if the detection in the Su and Finkbeiner sample is indeed real it might be related to accretion, bubble or jet activity in nearby (z < 0.2) AGN. Alternatively, given the right conditions, the similarity could be due to a chance occurrence caused by extragalactic background light absorption. Or else one must concede that the features are an artefact of instrumental or calibration issues.
Spatial Distribution of Crown Gall in a Commercial Nursery of Weeping Fig
Authors: Turechek W. W.
Published: December 2012

Agrobacterium larrymoorei causes tumors on weeping fig. The association between propagation and pathogen spread in mother trees and daughter branches was studied in a commercial nursery. The mother tree planting was scouted for tumors prior to and after propagation. Branches selected for propagation were tagged to track disease development. The spatial distribution of crown gall in the mother tree planting was characterized with runs, join-count, and spatial autocorrelation analyses. The association of disease in mother trees and daughter branches was characterized with cross-correlation analysis. The incidence of crown gall in the mother tree planting increased from 7% prior to propagation to 32% eight months after propagation. Of the 4193 daughter branches monitored, 3.8% developed tumors. Runs analysis indicated significant clustering of diseased mother trees. Significant cross-correlations between mother trees and daughter branches with symptoms of crown gall were detected out to a distance of two plants from the source. Although pruning shears were routinely soaked in a disinfectant in this nursery, the degree of sterilization achieved apparently was not sufficient to prevent pathogen transmission. This study suggests that alternative sanitation measures should be sought and that infected mother trees and their neighbors should be avoided for propagation.

Accepted for publication 5 November 2012. Published 26 November 2012.
Peripherally Inserted Central Catheters for Long‐term Parenteral Nutrition in Infants With Intestinal Failure
Authors: Piper Hannah G. , de Silva Nicole T. , Amaral Joao G. , Avitzur Yaron , Wales Paul W.
Published: December 2012

Background and Aim:

Infants with intestinal failure often require long‐term central access for delivery of parenteral nutrition (PN). Traditionally, surgically placed central venous catheters (CVCs) have been used; however, the complications associated with these catheters can lead to significant morbidity. Peripherally inserted central catheters (PICCs) are potentially superior to CVCs because they tend to be smaller, and can be placed without general anesthesia. The purpose of the study is to report the use of PICCs for long‐term administration of PN in infants with intestinal failure and compare with previously published catheter infection and venous thrombosis rates.

Methods:

A 4‐year review of infants younger than 12 months with intestinal failure and a PICC for PN delivery was performed to determine the incidence of catheter‐related bloodstream infections (CRBSIs) and PICC‐associated venous thrombosis. The complication rates were compared with those reported for CVCs and PICCs in the pediatric literature.

Results:

A total of 45 infants with intestinal failure, receiving PN through a PICC were included in the study. Data from 95 PICCs accounting for 10,189 catheter days were collected. The overall incidence of CRBSI was 5.3/1000 catheter days and the incidence of venous thrombosis was 2.0/1000 catheter days.

Conclusions:

PICCs offer an advantage over CVCs in that they can often be inserted without a general anesthesia and do not require manipulation of the vein. Given the low rate of CRBSI and venous thrombosis, we recommend PICCs for infants with intestinal failure requiring PN.
Patterns of viral infection in honey bee queens
Authors: Francis Roy Mathew , Nielsen Steen Lykke , Kryger Per
Published: December 2012

The well-being of a colony and replenishment of the workers depends on a healthy queen. Diseases in queens are seldom reported, and our knowledge on viral infection in queens is limited. In this study, 86 honey bee queens were collected from beekeepers in Denmark. All queens were tested separately by two real-time PCRs: one for the presence of deformed wing virus (DWV), and one that would detect sequences of acute bee-paralysis virus, Kashmir bee virus and Israeli acute paralysis virus (AKI complex). Worker bees accompanying the queen were also analysed. The queens could be divided into three groups based on the level of infection in their head, thorax, ovary, intestines and spermatheca. Four queens exhibited egg-laying deficiency, but visually all queens appeared healthy. Viral infection was generally at a low level in terms of AKI copy numbers, with 134/430 tissues (31 %) showing the presence of viral infection ranging from 101 to 105 copies. For DWV, 361/340 tissues (84 %) showed presence of viral infection (DWV copies ranging from 102 to 1012), with 50 tissues showing viral titres >107 copies. For both AKI and DWV, the thorax was the most frequently infected tissue and the ovaries were the least frequently infected. Relative to total mass, the spermatheca showed significantly higher DWV titres than the other tissues. The ovaries had the lowest titre of DWV. No significant differences were found among tissues for AKI. A subsample of 14 queens yielded positive results for the presence of negative-sense RNA strands, thus demonstrating active virus replication in all tissues.