bluuebunny/crossref_metadata_2025 huggingface dataset:
Medium‐Throughput Microarray‐Based Approach for Toxicogenomic Profiling of Small Molecules
Authors: Vass Laura , Kis Zoltán , Fehér Liliána Z. , Zvara Ágnes , Lőrincz Zsolt , Borbola Ildikó , Cseh Sándor , Kulin Sándor , Ürge László , Dormán György , Puskás László G.
Published: October 2006

Investigating the interaction between small molecules and cells by DNA‐microarrays or in human type phenotypic assays is very labor‐intensive and expensive, therefore such parallel characterization of large compound libraries is currently economically not feasible. Therefore, we developed our own ToxicoScreenTM microarrays, consisting of 48 subarrays, for medium‐throughput analysis. Each subarray can be individually addressed and has probes for genes coding ABC transporters, carbohydrate sulfotransferases, cytochrome P450, glutathione S‐transferases, UDP‐glucosyltransferases, heat‐shock proteins, acyl‐coenzyme A oxidases, receptors, and metallothioneins. Microarray analysis was performed in an array‐in‐array format which enabled us to screen 8–24 compounds per microarray providing 6–2 replica results in one hybridization step. To validate our platform, gene‐expression changes in human hepatocarcinoma (HepG2) cells in response to six toxic compounds were determined in eight replica experiments. Two normalization strategies were tested. We found that normalization to the total intensities of one subarray gave the best result. Among 121 genes only two resulted in significantly non‐relevant data. We found general toxicology markers such as ABC transporters, lipase A, growth arrest and DNA damage‐inducible alpha, PPARα, and glutathione S‐transferase theta 1 and M1. The developed microarray platform can be used to assess the possible toxic side effects of certain drug candidates and to determine fingerprints as well.
A simple and linear time randomized algorithm for computing sparse spanners in weighted graphs
Authors: Baswana Surender , Sen Sandeep
Published: October 2006

Let G = (V,E) be an undirected weighted graph on |V | = n vertices and |E| = m edges. A t‐spanner of the graph G, for any t ≥ 1, is a subgraph (V,ES), ES ⊆ E, such that the distance between any pair of vertices in the subgraph is at most t times the distance between them in the graph G. Computing a t‐spanner of minimum size (number of edges) has been a widely studied and well‐motivated problem in computer science. In this paper we present the first linear time randomized algorithm that computes a t‐spanner of a given weighted graph. Moreover, the size of the t‐spanner computed essentially matches the worst case lower bound implied by a 43‐year old girth lower bound conjecture made independently by Erdős, Bollobás, and Bondy & Simonovits.

Our algorithm uses a novel clustering approach that avoids any distance computation altogether. This feature is somewhat surprising since all the previously existing algorithms employ computation of some sort of local or global distance information, which involves growing either breadth first search trees up to θ(t)‐levels or full shortest path trees on a large fraction of vertices. The truly local approach of our algorithm also leads to equally simple and efficient algorithms for computing spanners in other important computational environments like distributed, parallel, and external memory. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007
Fast mixing for independent sets, colorings, and other models on trees
Authors: Martinelli Fabio , Sinclair Alistair , Weitz Dror
Published: October 2006

We study the mixing time of the Glauber dynamics for general spin systems on the regular tree, including the Ising model, the hard‐core model (independent sets), and the antiferromagnetic Potts model at zero temperature (colorings). We generalize a framework, developed in our recent paper (Martinelli, Sinclair, and Weitz, Tech. Report UCB//CSD‐03‐1256, Dept. of EECS, UC Berkeley, July 2003) in the context of the Ising model, for establishing mixing timeO(nlogn), which ties this property closely to phase transitions in the underlying model. We use this framework to obtain rapid mixing results for several models over a significantly wider range of parameter values than previously known, including situations in which the mixing time is strongly dependent on the boundary condition. We also discuss applications of our framework to reconstruction problems on trees. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007
Towards an Expanded Dramaturgical Practice: A Report on ‘The Dramaturgy and Cultural Intervention Project’
Authors: ECKERSALL PETER
Published: October 2006

This essay is a report on the Dramaturgy and Cultural Intervention Project (Dramaturgies), a forum for the investigation of issues in professional dramaturgical practice in Australia. It reviews the textual orientation of historical theatre practice in Australia before describing a series of events aiming to promote a wider and more culturally interactive understanding of dramaturgy. New forms of dramaturgy arising in response to the post-dramatic turn in theatre are discussed as a basis for exploring an expanded dramaturgical practice. Proposals for a politics of dramaturgy that revive theatre as a forum for social critique conclude the essay. While specific to one set of theatre interventions, it is intended that the proposals discussed herein have wider applications.
The maximum range and timing of excitatory contextual modulation in monkey primary visual cortex
Authors: ALEXANDER D.M. , WRIGHT J.J.
Published: October 2006

Contextual modulations of receptive field properties by distal stimulus configurations have been shown for a variety of stimulus paradigms. A survey of excitatory contextual modulation data for V1 shows the maximum scale of interactions, measured in terms of distance in V1, to be between 10 mm and 30 mm. Different types of excitatory contextual modulation in V1 occur throughout the interval of 40–250 ms after stimulus delivery. This window provides opportunity for global propagation of visual contextual information to a subset of V1 neurons, via several routes within the visual system. We propose a number of experiments and analyses to confirm the results from this empirical survey.
Directional shifts in the barber pole illusion: Effects of spatial
frequency, spatial adaptation, and lateral masking
Authors: LALANNE CHRISTOPHE , LORENCEAU JEAN
Published: October 2006

We report the results of psychophysical experiments with the so-called
barber pole stimulus providing new insights on the neuronal processes
underlying the analysis of moving features such as terminators or
line-endings. In experiment 1, we show that the perceived direction of a
barber pole stimulus, induced by line-ending motion, is highly dependent
on the spatial frequency and contrast of the grating stimulus: perceived
direction is shifted away from the barber pole illusion at high spatial
frequency in a contrast dependent way, suggesting that line-ends are not
processed at high spatial scales. In subsequent experiments, we use a
contrast adaptation paradigm and a masking paradigm in an attempt to
assess the spatial structure and location of the receptive fields that
process line-endings. We show that the adapting stimulus that weakens most
the barber pole illusion is localized within the barber pole stimulus and
not at line-endings' locations. Current models of line-endings'
motion processing are discussed in the light of these psychophysical
results.
Dark rearing reveals the mechanism underlying stimulus size tuning
of superior colliculus neurons
Authors: RAZAK KHALEEL A. , PALLAS SARAH L.
Published: October 2006

Neurons in the superficial layers of the midbrain superior colliculus
(SC) exhibit distinct tuning properties for visual stimuli, but, unlike
neurons in the geniculocortical visual pathway, most respond best to
visual stimuli that are smaller than the classical receptive field (RF).
The mechanism underlying this size selectivity may depend on the number
and pattern of feedforward retinal inputs and/or the balance between
inhibition and excitation within the RF. We have previously shown that
chronic blockade of NMDA receptors (NMDA-R), which increases the
convergence of retinal afferents onto SC neurons, does not alter size
selectivity in the SC. This suggests that the number of retinal inputs
does not determine size selectivity. Here we show, using single unit
extracellular recordings from the SC of normal hamsters, that size
selectivity in neurons selective for small stimulus size is correlated
with the strength of inhibition within the RF. We also show that dark
rearing causes concomitant reductions in both inhibition and size
selectivity. In addition, dark rearing increases the percentage of neurons
non-selective for stimulus size. Finally, we show that chronic blockade of
NMDA-R, a procedure that does not alter size tuning, also does not change
the strength of inhibition within the RF. Taken together, these results
argue that inhibition within the RF underlies selectivity for small
stimulus size and that inhibition must be intact for size tuning to be
preserved after developmental manipulations of activity. In addition,
these results suggest that regulation of the balance between excitation
and inhibition within the RF does not require NMDA-R activity but does
depend on visual experience. These results suggest that developmental
experience influences neural response properties through an alteration of
inhibitory circuitry.
A high frequency resonance in the responses of retinal ganglion cells to rapidly modulated stimuli: A computer model
Authors: MILLER J.A. , DENNING K.S. , GEORGE J.S. , MARSHAK D.W. , KENYON G.T.
Published: October 2006

Brisk Y-type ganglion cells in the cat retina exhibit a high frequency resonance (HFR) in their responses to large, rapidly modulated stimuli. We used a computer model to test whether negative feedback mediated by axon-bearing amacrine cells onto ganglion cells could account for the experimentally observed properties of HFRs. Temporal modulation transfer functions (tMTFs) recorded from model ganglion cells exhibited HFR peaks whose amplitude, width, and locations were qualitatively consistent with experimental data. Moreover, the wide spatial distribution of axon-mediated feedback accounted for the observed increase in HFR amplitude with stimulus size. Model phase plots were qualitatively similar to those recorded from Y ganglion cells, including an anomalous phase advance that in our model coincided with the amplification of low-order harmonics that overlapped the HFR peak. When axon-mediated feedback in the model was directed primarily to bipolar cells, whose synaptic output was graded, or else when the model was replaced with a simple cascade of linear filters, it was possible to produce large HFR peaks but the region of anomalous phase advance was always eliminated, suggesting the critical involvement of strongly non-linear feedback loops. To investigate whether HFRs might contribute to visual processing, we simulated high frequency ocular tremor by rapidly modulating a naturalistic image. Visual signals riding on top of the imposed jitter conveyed an enhanced representation of large objects. We conclude that by amplifying responses to ocular tremor, HFRs may selectively enhance the processing of large image features.
Tidal synchronicity of the 26 December 2004 Sumatran earthquake and its aftershocks
Authors: Crockett R. G. M. , Gillmore G. K. , Phillips P. S. , Gilbertson D. D.
Published: October 2006

The frequency of earthquake incidence along the Andaman/Sunda/Java Trench plate‐boundary region has been investigated for the ten‐lunar‐month period 28 October 2004–19 August 2005, encompassing the 26 December 2004 earthquake. During this period variations in earthquake activity correlate with the tidal‐force cycles: maxima in earthquake activity occur around the times of new and full moons, typically lagging by 0–3 days. This relationship is consistent with earthquake inducement via ocean tidal loading. Also, during this period the earthquake incidence associated with new and full moons at the western end of the region was (a) 38% and (b) 86% higher than the period averages for the full and declustered major‐earthquake catalogs respectively.
Self‐consistent modeling of magnetic fields and plasmas in the inner magnetosphere: Application to a geomagnetic storm
Authors: Zaharia Sorin , Jordanova V. K. , Thomsen M. F. , Reeves G. D.
Published: October 2006

A geomagnetic storm model needs to take into account the coupling between magnetic field and plasma, as the storm‐time field in the inner nightside magnetosphere can be very depressed compared to that of the Earth dipole, thus significantly modifying plasma transport. In this paper we extend our previous “one‐way” coupling between a kinetic ring current model and a magnetospheric force‐balance model to a fully magnetically self‐consistent approach, in which the force‐balanced fields are fed back into the kinetic model to guide its evolution. The approach is applied to simulating the 21–23 April 2001 “GEM Storm Challenge” event. We use boundary and initial conditions for the kinetic model from several spacecraft, and magnetic flux boundaries for the equilibrium code from an empirical magnetic field model. We find significant differences in the self‐consistent results compared to those obtained from the kinetic model with a dipolar background field (with the same particle boundary conditions and electric fields), due mainly to changes in the particle drifts. In addition to large depressions in the nightside magnetic field values compared to a dipolar field, we also find significantly lower particle density and perpendicular plasma pressure in the inner magnetosphere in the self‐consistent case, as well as local, narrow pressure peaks and strongly enhanced plasma βp in localized regions on the nightside.
Petschek‐type magnetic reconnection exhausts in the solar wind well inside 1 AU: Helios
Authors: Gosling J. T. , Eriksson S. , Schwenn R.
Published: October 2006

Petschek‐type reconnection exhausts can be recognized in solar wind plasma and magnetic field data as accelerated or decelerated plasma flows confined to magnetic field reversal regions. Using that characteristic signature, we have identified 28 reconnection exhausts in the Helios 1 and 2 data, thus extending observations of exhausts associated with local, quasi‐stationary reconnection in the solar wind inward to heliocentric distances of 0.31 AU. Most of the exhaust jets identified in the Helios data had the same general physical character as solar wind exhausts observed at greater heliocentric distances and latitudes by ACE, Wind, and Ulysses. The magnitude of the velocity changes from outside to inside the exhausts was generally comparable to, but somewhat less than (by a factor of 0.75 on average), the inflow Alfvén speeds. In a few of the Helios events, plasma number densities within the exhausts were intermediate to densities observed immediately outside, indicating that transitions from outside to inside the exhausts were not always slow‐mode‐like on both sides. We have identified pairs of closely spaced, but independent, reconnection exhausts bounding regions where the heliospheric magnetic field folded back toward the Sun. We find that plasma and magnetic field conditions in the high‐speed wind from coronal holes are not generally favorable for sustained magnetic reconnection and for the formation and propagation of Petschek‐type exhausts. Finally, we have not yet identified reconnection events common to both spacecraft, partially because of a relative lack of times when high data rate observations were available from both spacecraft.
A new time evolving Gaussian series representation of the imaginary time propagator
Authors: Shao Jiushu , Pollak Eli
Published: October 2006

Frantsuzov and Mandelshtam [J. Chem. Phys. 121, 9247 (2004)] have recently demonstrated that a time evolving Gaussian approximation (TEGA) to the imaginary time propagator exp(−βH) is useful for numerical computations of anharmonically coupled systems with many degrees of freedom. In this paper we derive a new exact series representation for the imaginary time propagator whose leading order term is the TEGA. One can thus use the TEGA not only as an approximation but also to obtain the exact imaginary time propagator. We also show how the TEGA may be generalized to provide a family of TEGA’s. Finally, we find that the equations of motion governing the evolution of the center and width of the Gaussian may be thought of as introducing a quantum friction term to the classical evolution equations.
10
kHz
repetitive high-resolution TV Thomson scattering on TEXTOR: Design and performance (invited)
Authors: van der Meiden H. J. , Varshney S. K. , Barth C. J. , Oyevaar T. , Jaspers R. , Donné A. J. H. , Kantor M. Yu. , Kouprienko D. V. , Uzgel E. , Biel W. , Pospieszczyk A. , Team TEXTOR
Published: October 2006

In late 2003 a 10kHz multiposition Thomson scattering diagnostic with high spatial resolution became operational on the TEXTOR tokamak. In the initial phase of operation, one burst of 18 pulses of 12J each with a repetition rate of 5kHz could be extracted from the laser system. The installation of a low-dope ruby rod (spring 2005) resulted in a system, which can deliver higher pulse energy and moreover a divergence of better than 0.7mrad, leading to a big improvement in the detection of Thomson scattering photons. Furthermore, the number of laser pulses in one burst could be extended to even more than 30. The achieved laser energy of more than 15J∕pulse makes it possible to measure electron temperature and density profiles with an observational error of 8% on the electron temperature (Te) and 4% on the electron density (ne) at ne=2.5×1019m−3, per spatial element of 7.5mm. The viewing optics enables sampling of either the full plasma diameter of 900mm with 120 spatial channels of 7.5mm each or a 160mm long edge chord with 98 spatial channels of 1.7mm each. The system, which has recently become available for physics exploration, has already been used to study the structure of m=2 magnetic islands and the response of the plasma to off-axis electron cyclotron resonance heating.
Geometric prequantization of the moduli space of the vortex equations on a Riemann surface
Authors: Dey Rukmini
Published: October 2006

The moduli space of solutions to the vortex equations on a Riemann surface are well known to have a symplectic (in fact, Kähler) structure. We show this symplectic structure explictly and proceed to show a family of symplectic (in fact, Kähler) structures ΩΨ0 on the moduli space, parametrized by Ψ0, a section of a line bundle on the Riemann surface. Next, we show that corresponding to these, there is a family of prequantum line bundles PΨ0 on the moduli space whose curvature is proportional to the symplectic forms ΩΨ0.
Features of the electronic spectrum and anomalous magnetism in the compounds YbPb3, YbSn3, CaPb3, and CaSn3
Authors: Baranovskiy A. E. , Grechnev G. E. , Svechkarev I. V.
Published: October 2006

A theoretical study is made of the features of the band structure and magnetic susceptibility χ in the isovalent compounds YbP3, YbSn3, CaPb3, and CaSn3 with the AuCu3 lattice. It is shown that their anomalous, strongly temperature-dependent diamagnetism is due to the presence of points of degeneracy of the bands near the Fermi level. Analysis of the behavior of χ(T) gives refined values of the energies of the degeneracy points as precision reference marks in the band spectrum of these compounds.
Metal foil method for noncontact measurement of lateral vibrations of a nonmetallic cylinder by a solenoid
Authors: Han Soon Woo , Bang Young Bong , Kim Yoon Young
Published: October 2006

This investigation shows that if a solenoid encircles a metal foil loop wound around a nonmetallic cylinder vibrating laterally, an electromotive force is induced in the solenoid. The induction is possible only when the foil loop is complete and an antisymmetric magnetic field is applied to the foil. In this work, stationary permanent magnets were used. Because the solenoid is the sensing element, no physical contact between the element and a test specimen is required. The effects of the metal foil thickness and width on the measurement sensitivity were studied and vibration modal testing of an acryl cylinder was performed.
Self-selected apex angle distribution in aluminum nitride and indium nitride nanotips
Authors: Chattopadhyay Surojit , Chen Kuei-Hsien , Shi Shih-Chen , Wu Chien-Ting , Chen Cheng-Hsuan , Chen Li-Chyong
Published: October 2006

A “step-edge” model has been proposed to explain the growth of solid nanotips of aluminum nitride (AlN) and indium nitride (InN) grown by thermal and metal organic chemical vapor depositions, respectively. The model predicts a set of apex angles that solid AlN and InN nanotips can have. A statistical distribution of the apex angle in InN nanotips indicates the discrete set of apex angles and its probability of nucleation.
High ionic conductivity in ultrathin nanocrystalline gadolinia-doped ceria films
Authors: Huang Hong , Gür Turgut M. , Saito Yuji , Prinz Fritz
Published: October 2006

High ionic conductivities were observed in ultrathin nanocrystalline gadolinia-doped ceria (GDC) films with thicknesses comparable to the grain size (20–50nm). Conductivities were determined to be effectively three to four orders of magnitude higher relative to those of thicker films (>500nm). The distinct properties in ultrathin GDC films were attributed to the reduction of cross grain boundary resistance and the segregation of the Gd dopants in the vicinity of grain boundaries.
Epitaxially grown MnAs∕GaAs lateral spin valves
Authors: Saha D. , Holub M. , Bhattacharya P. , Liao Y. C.
Published: October 2006

The authors report magnetoresistance of lateral spin valves fabricated from an epitaxially grown MnAs∕GaAs heterostructure and utilizing a Schottky tunnel barrier for efficient spin injection. A coercive field difference between the two ferromagnetic MnAs contacts is obtained by a difference in aspect ratio. Peak magnetoresistances of 3.6% at 10K and 1.1% at 125K are measured for a 0.5μm channel length spin valve. The authors observe an exponential decay of the peak magnetoresistance with increasing channel length, which is indicative of diffusive spin transport. The magnetoresistance increases with increasing bias and with decreasing temperature. Control experiments have been carried out to confirm the spin-valve effect.
Dependence of carrier lifetime in germanium on resisitivity and carrier injection level
Authors: Gaubas E. , Vanhellemont J.
Published: October 2006

The dependence of carrier lifetime on resistivity and carrier injection level in germanium crystals is studied using microwave probing of optically excited samples. Bulk lifetimes in the range between 30ns and 500μs are measured. The carrier lifetime decreases with decreasing resistivity and increases with increasing excitation level. Possible mechanisms are discussed and it is shown that the carrier recombination transients are driven by a system of recombination and trapping centers.
Stereo Motion Transparency Processing Implements an Ecological Smoothness Constraint
Authors: Calabro Finnegan J , Vaina Lucia M
Published: October 2006

Transparent motion stimuli allow us to investigate how visual motion is processed in the presence of multiple sources of information. We used stereo random-dot kinematograms to determine how motion processing is affected by the difference in direction and depth of two overlapping motion components. Observers judged whether a noise dot display contained one or two directions of motion. For all disparity differences, performance did not change among angles greater than 60°, but the ability to detect transparent motion fell dramatically as the direction difference decreased below 60°. When a disparity difference was added between the two motion components, detection became easier. We compared these results to an ideal-observer model limited by stimulus uncertainty and low-level sources of internal noise. The resulting measure of efficiency—the ratio of human to model performance—reflects changes in how motion stimuli are being processed. A decrease of both the direction and disparity differences had the effect of decreasing efficiency. These results suggest that the mechanism processing transparent motion may implement a smoothness constraint that tends to combine similar motions into a single percept.
The Influence of Depth Segmentation on Colour Constancy
Authors: Werner Annette
Published: October 2006

In real scenes, surfaces in different depth planes often differ in the luminance and chromatic content of their illumination. Scene segmentation is therefore an important issue when considering the compensation of illumination changes in our visual perception (lightness and colour constancy). Chromatic adaptation is an important sensory component of colour constancy and has been shown to be linked to the two-dimensional spatial structure of a scene (Werner, 2003 Vision Research43 1611 – 1623). Here, the question is posed whether this cooperation also extends to the organisation of a scene in depth. The influence of depth on colour constancy was tested by introducing stereo disparity, whereby the test patch and background were perceived in either the same or one of five different depth planes (1.9 – 57 min of arc). There were no additional cues to depth such as shadows or specular highlights. For consistent illumination changes, colour constancy was reduced when the test patch and background were separated in depth, indicating a reduction of contextual influences. An interaction was found between the influences of stereo depth and spatial frequency on colour constancy. In the case of an inconsistent illumination change, colour constancy was reduced if the test patch and background were in the same depth plane (2-D condition), but not if they were separated in depth (3-D condition). Furthermore, colour constancy was slightly better in the 3-D inconsistent condition than in the 2-D inconsistent condition. It is concluded that depth segmentation supports colour constancy in scenes with inconsistent illumination changes. Processes of depth segmentation are implemented at an early sensory stage of colour constancy, and they define visual regions within which the effects of illuminant changes are discounted for separately. The results support recent models that posit such implementation of scene segmentation in colour constancy.
Ligand substitution kinetics of iron(III) in aprotic solvents
Authors: Carr JT , Treloan PA
Published: October 2006

The complexation reactions
of NCS- and Br- with iron(III) have been studied in N,N-dimethyl-formamide,
and the temperature activation parameters determined. The observed forward rate
constants are 114±5 and 69±31, mol-1 s-1, the activation enthalpies are
48+±3 and 74±4 kJ mol-1, and the activation entropies are -45±8 and 40±10 J
K-1 mol-1, respectively, at 298 K and 0.5 M ionic strength. The complexation
reactions of NCS- with iron(III) in dimethyl sulfoxide have been studied at
ionic strengths of 0.1, 0.3 and 0.5 M, and over a range of temperatures. The
observed forward rate constant is 55±31. Mol-1 s-1, the activation enthalpy
is 42±3 kJ mol-1, and the activation entropy is -70±30 J K-1 mol-1 at 298 K
and 0.5 M ionic strength. It is proposed that the substitution reactions of
iron(111) in the aprotic solvents N,N-dimethyl- formamide and dimethyl
sulfoxide proceed through an associative interchange (Ia) mechanism.
The reactivity of p-nitrophenyl esters with surfactants in apolar solvents. V. p-Nitrophenyl acetate in benzene solutions of butane-1,4-diamine bis(dodecanoate)
Authors: O'Conner CJ , Lomax TD
Published: October 2006

The rate of decomposition
of p-nitrophenyl
acetate in benzene in the presence of butane-1,4-diamine bis(dodecanoate) (budb)
has been measured at temperatures between 333 and 353 K. The data fit a rate
equation which consists of a term arising from micellar catalysis and a term
arising from a bimolecular reaction between the ester and the components of budb. Arrhenius parameters have been
estimated for the two reaction modes and compared with newly extended data for
the similar reaction with dodecylammonium propionate
(dap). 13C n.m.r. analysis of the products from there action of p-nitrophenyl propionate in the presence of dap has revealed
that the amide is formed by an aminolysis reaction.
The decrease in reaction rate observed with increasing water concentration is
interpreted in terms of a biphasic water environment.
Acid-catalysed dimerization of exo-2-Phenyl-exo-5,exo-6-trimethylenenorbornan-endo-2-ol
Authors: Butler O , Coxon JM , Steel PJ
Published: October 2006

The dimeric products formed
by reaction of exo-2-phenyl-exo-5,exo-6-trimethylenenorbornan-endo-2-
ol (1) with formic acid at 70� are identified as:
(1RS,2RS,6RS,7RS,8RS,1'SR,2'SR,10'SR,11'RS,- 12'RS,16'SR) - 2'- phenylspiro[tricyclo[5,2,1,02,6]decane- 8,9'-pentacyclo[9,5,1,02,10,03,8,012,16]hepta-deca-3',5',7'-triene]
(5) and from X-ray diffraction data: (1RS,2RS,6RS,7RS,8RS,l'RS,2'RS,10'RS,-1l'SR,12'SR,16'RS)-2'-phenylspiro[tricyclo[5,2,1,02,6]decane-8,9'-pentacyclo[9,5,1,02,10,03,8,012,16]-
heptadeca-3',5',7'-triene] (8) refined to a residual of R 0.069 (1529 observed
reflections). The mechanistic implications of the formation of dimers (5) and (8) and the influence of the exo-trimethylene
bridge on the dimerization process are discussed.
The chemistry of lauren-1-ene. IV. Rearrangement of a ring A seco derivative
Authors: Corbett RE , Jogia MK , Lauren DR , Weavers RT
Published: October 2006

The structure of a diene
produced by acid-catalysed rearrangement of a ring A seco laurenane derivative
has been confirmed by spectral analysis of a dimethyl acetylenedicarboxylate
adduct. The course of an ene reaction undergone by the above adduct is described.
Linear relationship between molecular rotation and bond refraction in organophosphorus compounds
Authors: Poh B
Published: October 2006

The molecular rotations,
[M]D of eight series of organophosphorus
compounds have been satisfactorily correlated with the sum of their bond
refractions, ΣRD, by using the empirical equation [M]D
= mΣRD+I where m and I are constants for a given series of compounds
and D denotes the sodium D line.
Photochemical synthesis of 8H-Benzo[g]- 1,3-benzodioxolo[6,5,4-de]quinolin-8-one (Liriodenine) via 7-Methyl-6,7-dihydro-5H-benzo[g]-1,3-benzodioxolo[6,5,4-de]-quinoline
Authors: Nimgirawath S , Taylor WC
Published: October 2006

Irradiation of ethyl
(Z)-1-(2-bromobenzylidene)-6,7-methylenedioxy-1,2,3,4-tetrahydroisoquinoline-2-carboxylate
(4) afforded ethyl
6,7-dihydro-5H-benzo[g]-1,3-benzodioxolo[6,5,4-de]quinoline-7-carboxylate (5),
the reduction of which with lithium aluminium hydride-aluminium chloride gave the
7-methyl derivative (6). Oxidation of (6) with lead tetraacetate afforded liriodenine (8H-benzo[g]-1,3-benzodioxolo[6,5,4-delquinolin-8-one)(1)
in moderate yield.
Valence-bond studies on SiH3
Authors: Jans R , Maclagan RGAR
Published: October 2006

Valence-bond calculations
are reported for the ground state of SiH3, a contracted double-zeta
basis set being used. Without the use of silicon 3d orbitals,
a planar structure is predicted, but the inclusion of 3d orbitals
in the basis set leads to a pyramidal structure being predicted. The covalent
structure is the most important structure. Structures in which the silicon atom
carries a positive charge favour a pyramidal structure, but those in which the
silicon atom carries a negative charge tend to favour a planar structure.
Metal-proton interactions in benzylamine complexes of palladium(II): The effect of methyl substitution at nitrogen and the role of the interaction during cyclopalladation. X-ray crystal structure of tetrabenzylaminepalladium(II) acetate chloride
Authors: Jones TC , Nielson AJ , Rickard CE
Published: October 2006

Reaction of Pd(O2CMe)2
with PhCH2NH2 leads to either Pd(NH2CH2Ph)2(O2CMe)2
or [Pd(NH2CH2Ph)4] [O2CMe]2.
The X-ray crystal structure of [Pd(NH2CH2Ph)4]
[Cl] [O2CMe] shows pairs of [Pd(NH2CH2Ph)4]2+
ions held together by hydrogen bonds from the NH proton to chlorine and oxygen
atoms of the anions, and the absence of interactions between phenyl ring ortho
protons and the metal. PhCH2NHMe reacts with Pd(O2CMe)2
giving Pd(NHMeCH2Ph)2(O2CMe) and PhCH2NMe2
gives the cyclometallate [Pd(NMe2CH2Ph-C,N)(�-O2CMe)]2.
1H N.M.R. spectra indicate that the complexes Pd(NMe2CH2Ph)(L)(O2CMe)2
(L = PhNH2, o-MeC6H4NH2)
prepared from [Pd(L)(O2CMe)(�-O2CMe)]2,
contain an interaction of the benzylamine ortho aromatic protons with the metal
whereas Pd(NHMeCH2Ph)(L)(O2CMe)2 (L = o-MeC6H4NH2)
does not. 1H n.m.r. analysis of PdCl42- and
PhCH2NMe2 in (2Hl)methanol at 400
MHz indicates a 1 : 1 reaction stoichiometry and
metal-proton interactions in intermediates containing above-plane and in-plane
geometry of the aromatic ring, before metallation
takes place. A 400-MHz spectral analysis of Pd(O2CMe), and PhCH2NMe2
in CDCl, suggests similarly orientated species arise
in the reaction giving [Pd(NMe2CH2Ph-C,N)(�-O2CMe)]2.
Crystal structures of Bis[(ethane-1,2-diyl)bis(diphenylphosphine)]-palladium(II) and -platinum(II) dichloride dichloromethane and Dichloro[(ethane-1,2-diyl)bis(diphenylphosphine)]platinum(II) dichloromethane
Authors: Engelhardt LM , Patrick JM , Raston CL , Twiss P , White AH
Published: October 2006

The crystal structures of
the title compounds have been established by single-crystal X-ray diffraction
techniques at 295 K, being refined by least squares to residuals of 0.043,
0.036, 0.036 for 2057, 3176 and 3468 independent 'observed' reflections respectively.
Crystals of [Pd(diphos)2] C12
(1) (diphos = Ph2P(CH2)2PPh2)
are monoclinic, P21/c, with a
12.779(9), b 18.084(10), c 12.942(6) �, β 119.29(5)�, 22;
for the isostructural platinum analogue (2), a
12.789(4), b 18.099(7), c 12.965(4) �, β 1l9.39(2)�. Crystals of [PtCl2(diphos)].CH2Cl2, (3), are
orthorhombic, P212121, with a 21.360(6), b 13.499(4), c 9.551(5)�
Z 4. Complexes (1) and (2) are also solvated but the nature of the solvation is complicated by disorder and less clearcut than in (3). In (1), Pd-P distances are 2.342(2),
2.347(2) � in a centrosymmetric molecule; in (2), Pt-P distances are 2.332(2),
2.335(2) �, while in (3), Pt-P distances are 2.230(2), 2.224(3) � and Pt-Cl are
both 2.355(2) � [cf. 2.233(2), 2.226(2), (2.361(2), 2.357(2))� respectively for
the previously studied palladium analogue].
Thermolytic conversion of an acetamido-substituted cyclopropane into a cyclopentenone. Crystal and molecular structures of 2-Spiro-substituted Benzofuran-3-ones
Authors: Becker H , Skelton BW , White AH
Published: October 2006

The thermolysis
of an N-methylacetamido
cyclopropane, spiro-substituted
by a benzofuran-3-one moiety, was found to result in the elimination of
methylamine and the formation of the correspondingly spiro-substituted
cyclopentenone. The structures of starting material and product were determined
by single-crystal X-ray diffraction methods and a mechanism for the
elimination/ring enlargement reaction is proposed on the basis of the X-ray
results.
New Mannich base ligands
Authors: Hodgkin JH
Published: October 2006

A series of
low-molecular-weight aminomethylphenol compounds have
been synthesized as model analogues of new Cu2+ and Fe3+
chelating polymers. Preliminary colour tests with
these two ions were used to indicate the structural features essential for
polymer chelate formation.
Tropical Marine Algae. VIII. The Structural Determination of Novel Sesquiterpenoid Metabolites From the Red Alga .Laurencia majuscula
Authors: Denys R , Coll JC , Bowden BF
Published: October 2006

An investigation of the natural products chemistry of the red alga Laurencia mujuscula from the Great Barrier Reef yielded three novel metabolites, (1), (2) and (3a), possessing a new sesquiterpenoid structural type. Known metabolites (6)-(11) were also isolated and the reassignment of n.m.r. spectral values for (11) is reported.
The Electrochemically Formed Palladium-Deuterium System. II. In situ Neutron Diffraction Studies
Authors: Dillon CT , Kennedy BJ , Elcombe MM
Published: October 2006

An in situ neutron diffraction study of the electrochemical formation of β-PdDx in 1 M LiOD at room temperature is described. Electrolysis at relatively high overpotentials for over 200 h resulted in the formation of β-PdD0.59 (a = 4.0422 Ǻ), with no evidence for the formation of a bulk phase with higher deuterium content or occupancy of the tetrahedral sites in the face-centred cubic lattice. The formation of a thin layer on the surface of the cathode with x > 0.59 could account for the observation of gas evolution once electrolysis is stopped. Evidence for hysteresis in the re-formation of palladium by oxidation of β-PdDx is also presented.
Phylogenetic analysis and alignment of behavioral sequences by direct optimization
Authors: Robillard Tony , Legendre Frédéric , Desutter‐Grandcolas Laure , Grandcolas Philippe
Published: October 2006

We propose a new approach to consider behavioral data in phylogenetic analyses. We show that behavior can be described as sequences of repeated units, and that these behavioral sequences can be analyzed under direct optimization in a way similar to molecular data. This approach provides repeatable hypotheses of homology for behavior when traditional criteria result in multiple alternatives or do not allow to propose any. We exemplify this approach by analyzing the calling songs of the North AmericanGryllusspecies under direct optimization. We first use two alternative coding schemes to describe the temporal patterns of the songs as sequences of repeated simple behaviors. We submit these behavioral data to phylogenetic analysis under direct optimization, first as separate analyses, and second in combination with molecular data and additional acoustic characters. The results show that the coding option that consists of discretizing the silent parts of the songs: (1) allows description of the songs in a more precise way; (2) discriminates further the songs between species; and (3) enhances the phylogenetic content of the behavioral sequences. Our study demonstrates that behavioral sequences can be transformed so that they can be used in genuine phylogenetic analysis, in isolation or combined with other data sets. We discuss how this approach may provide phylogenetic signal where none or little is usually available, and the applications to the study of the evolution of behavioral evolution.

© The Willi Hennig Society 2006.
Model for Leaching Behavior of Aluminosilicate Glasses Developed as Matrices for Immobilizing High‐Level Wastes
Authors: HARVEY K.B. , LITKE C.D.
Published: October 2006

A field trial initiated in 1960 has shown very low release rates of 137Cs and 90;Sr from aluminosilicate glasses developed as potential matrices for the immobilization of radioactive fission products. Recent laboratory work in closed glass‐water systems shows that certain sodium‐calcium aluminosilicate glasses effectively cease to dissolve in water after a short time. This behavior is thought to be associated with the formation of a protective mineralized surface layer. Models were developed for the release of radionuclides from a glass covered by a mineralized surface layer, with leaching in both closed and open systems. The leaching equation for release in an open system is fitted to 90Sr release data.
The System Magnesium Cordierite‐Cobalt Cordierite
Authors: Wandschneider Peter , Seifert Friedrich
Published: October 2006

A complete solid solution series exists between Mg2Al4Si5O18 and Co2Al4Si5O18 at temperatures below 1160°C. Above 1160°, Co cordierite breaks down into CoAl2O4 spinel and cristobalite. The thermal stability of the cordierite solid solution decreases with decreasing Mg content; at the Co/(Co+Mg)=0.3 composition incongruent melting of the cordierites is changed to a subsolidus breakdown.
Preparation of High‐Strength Apatite Ceramics
Authors: Kondo Kazuo , Okuyama Masahiko , Ogawa Hidetoshi , Shibata Yoshimasa , Abe Yoshihiro
Published: October 2006

A sintered apatite with enhanced strength was achieved by incorporating CaO‐P2O5/metal oxide frit. When BaO or Al203 were partially substituted for CaO in the frit composition, the sintered product was stronger because grain growth was retarded. The average bending strength of the strongest sintered apatite was 205.8 MP.
Enhanced Densification of Boehrmte Sol‐Gels by α‐Alumina Seeding
Authors: Kumagai Masato , Messing Gary L.
Published: October 2006

Boehmite sol‐gels were seeded by adding <2.0 wt%α‐alumina powder to a 20% boehmite hydrosol at pH =3. The seeded gel sintered to 98% of theoretical density after 100 min at 1200°C, whereas the unseeded gel had to be sintered at 1600°C to reach 94% of theoretical density. This difference results primarily from nucleation by the α‐alumina seeds and enhanced transformation of the boehmite to α‐alumina, such that a uniform, well‐ordered, fine‐grained α‐alumina micro‐structure forms prior to densification.
Effect of Crystallites on Thermal Shock Resistance of Cordierite Glass‐Ceramics
Authors: Fairbanks Carolyn J. , Lee Hong Lim , Haselman D. P. H.
Published: October 2006

Thermal shock behavior was compared for a cordierite glass and glass‐ceramics subjected to a water quench. Crystallization significantly increases the critical quenching temperature difference (ΔTc); this effect was attributed to enhanced strength and thermal conductivity offset by a corresponding increase in Young's modulus. The strength retained following thermal shock also increased significantly on crystallization for ΔT>ΔTC, probably as the result of stepwise increases in fracture toughness with increasing crack size of the glass‐ceramic.
Viscous Sintering of a Bimodal Pore‐Size Distribution
Authors: SCHERER GEORGE W.
Published: October 2006

The cylinder model, used previously to analyze the viscous sintering of flame hydrolysis preforms and gels, is shown to be consistent with other models of early‐ and late‐stage sintering. The model is then applied to a bimodal pore‐size distribution in which the different shrinkage rates of small and large pores produce local stresses. The effect of these stresses on the sintering rate is determined and shown to be substantial. Initially, the small pores accelerate the densification of the large pores; later, shrinkage of the isolated large pores is resisted by the sintered remains of the small pores. Consequently, the time to reach full density is nearly independent of the initial volume fraction of small pores.
A Theoretical Analysis of the Ring‐On‐Ring Loading Disk Test
Authors: FESSLER H. , FRICKER D. C.
Published: October 2006

The theoretical “thin‐plate” analysis of axisymmetrically loaded flat circular plates is extended to a “thick‐plate” solution by including shear between the load and support rings. The effect of friction at the contacts is included and shown to be important. Stresses for different overhangs and different coefficients of friction are evaluated. Stress‐volume and stress‐area integrals are used to determine material unit strengths. Some relevant experimental work is also reported.
Crystallization of a Glass‐Ceramic by Epitaxial Growth
Authors: HEADLEY T.J. , LOEHMAN R.E.
Published: October 2006

The crystallization mechanism in a modified Li2O‐Al2O3‐SiO2glass containing P2O5 nucleating agent was investigated by transmission electron microscopy, X‐ray diffraction, and differential thermal analysis. During an initial 1000°C treatment P205 and Li2O react to precipitate Li3PO4 crystallites. At lower temperatures cristobalite, lithium metasilicate, and lithium disilicate crystallize by epitaxial growth on those Li3PO4crystallites. Crystallographic orientation relations for epitaxy were determined by electron diffraction, and lattice misfits were found to be in the range –5.3 to +3.8%. These results provide the first direct proof that glass‐ceramics can crystallize by epitaxial growth on heterogeneous nuclei formed from intentionally added nucleating agents.
Oxide Fuels with Controlled Microstructure
Authors: ASSMANN H. , DOERR W. , PEEHS M.
Published: October 2006

The control of microstructural properties of UO2, UO2‐Gd2O3, and UO2‐PuO2 pellets for light water reactors and the relations of these properties to in‐reactor performance aspects are discussed for four groups of properties: (1) density/porosity, (2) pore structure, (3) grain structure, and (4) oxide phase structure of the mixed oxides. According to theoretical modelling, in‐reactor densification/swelling behavior mainly depends on the density and pore size distribution. The pore structure can be adapted to performance requirements by adequate methods during fuel production. The benefit of this approach has been proven by available operational experience and by postirradiation examinations. Tailoring of the grain structure allows the reduction of fission gas release and pellet/clad interaction, i.e., stress corrosion cracking of the zirconium alloy cladding. A safe and reliable operation is also attained with the mixed oxides by the control of the oxide phase structures, e.g., by avoiding thermal spiking.
Dependence of Grain‐Boundary Resistivity on Grain‐Boundary Density in Yttria‐Stabilized Zirconia
Authors: MIYAYAMA MASARU , YANAGIDA HIROAKI
Published: October 2006

The dependence of grain‐boundary resistivity and resistance per square centimeter of grain‐boundary surface on grain‐boundary density (D) in yttria‐stabilized zirconia was investigated using reported data. The grain‐boundary resistivity increased with increasing D in the high‐D region but was independent of D in the low‐D region. These results were interpreted in terms of intrinsic effects such as lattice irregularity and extrinsic effects such as impurity segregation.
Dynamic Fatigue Analysis of Indentation Flaws Using an Exponential‐Law Crack Velocity Function
Authors: RITTER JOHN E. , VICEDOMINE MICHAEL , BREDER KRISTIN , JAKUS KARL
Published: October 2006

The effect of residual contact stresses on the dynamic fatigue behavior of indentation flaws was analyzed using an exponential‐law crack velocity function based on stress corrosion theory. Analysis of strength data from Vickers‐indented soda‐lime glass specimens in water showed that the contact residual stress can be properly accounted for and that the exponential‐law fatigue parameters can be straightforwardly obtained.
Particle Rotation in Early Sintering
Authors: HSUEH CHUN‐HWAY , DE JONGHE LUTGARD C.
Published: October 2006

Shrinkage and rearrangement during the early stages of sintering are considered. In such rearrangement the sintering particles can experience both additional center‐to‐center stresses and bending moments arising from multiparticle interactions and asymmetrical neck formation. The response of a particle pair to the simultaneous action of these stresses is solved analytically in a cylindrical geometry.
Effect of Heating Time on the Thermal Stress Resistance of a Soda‐Lime‐Silica Glass
Authors: SAGER RAMON L. , TAWIL HENRI , HASSELMAN D. P. H.
Published: October 2006

A model study was conducted of the thermal fatigue and single‐cycle thermal shock resistance of indented soda‐lime‐glass rods heated over durations sufficiently short that thermal equilibrium was not reached prior to quenching into a water bath. The experimental results indicate that for short heating periods thermal fatigue life at fixed ΔT and the critical quenching temperature difference (Δ7c) for a single‐cycle quench significantly exceed the corresponding values obtained for specimens heated for sufficiently long periods that conditions of final thermal equilibrium were obtained prior to quenching. The implications of these results for single‐cycle and multicycle thermal shock testing are discussed.