bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidative Addition von N‐Chlortriphenylphosphanimin an Phosphortrichlorid und Antimontrichlorid. Kristallstrukturen von (Cl3PNPPh3)2[PCl6][ClHCl],[SbCl4(HNPPh3)2][SbCl6] und [Sb(NPPh3)4][SbCl6]
Authors: Neumüller Bernhard , Dehnicke Kurt
Published: May 2005

Oxidative Addition of N‐chlorotriphenylphosphoraneimine onto Phosphorus(III) Chloride and Antimony(III) Chloride. Crystal Structures of (Cl3PNPPh3)2[PCl6][ClHCl], [SbCl4(HNPPh3)2][SbCl6], and [Sb(NPPh3)4][SbCl6]

Phosphorus(III) chloride reacts with N‐chlorotriphenylphosphoraneimine, ClNPPh3, in CH2Cl2 solution strongly exothermically via oxidative addition to give (Cl3PNPPh3)2[PCl6][ClHCl] (1). As a by‐product, Ph3PNP(O)Cl2 can be obtained, which is formed from PCl3 and ClNPPh3 in the presence of POCl3. In contrast to these results, antimony(III) chloride reacts with ClNPPh3 in CH2Cl2 solution to give a mixture of the phosphoraneimine complex [SbCl4(HNPPh3)2][SbCl6] (2) and the phosphoraneiminato complex [Sb(NPPh3)4][SbCl6] (3). The complexes 1‐3 were characterized by IR spectroscopy and by single crystal X‐ray determinations.

1: Space group C2/c, Z = 4, lattice dimensions at 193 K: a = 3282.0(2), b = 798.7(1), c = 1926.1(2) pm, β = 107.96(1)°, R1 = 0.0302. 1 contains [Cl3PNPPh3]+ cations with PN bond lengths of 152.5(2) and 160.9(2) pm, and a PNP bond angle of 140.5(1)°.

2·CH2Cl2: Space group ${\rm P}{\bar 1}$, Z = 2, lattice dimensions at 193 K: a = 1031.2(1), b = 1448.3(2), c = 1811,4(2) pm, α = 70.96(1)°, β = 87.67(1)°, γ = 75.37(1)°, R1 = 0.0713. 2·CH2Cl2 contains cations [SbCl4(HNPPh3)2]+ with octahedrally coordinated Sb atom and the HNPPh3 ligand molecules being in trans‐position. Sb–N bond lengths are 207.6(6) and 209.3(6) pm, PN bond lengths 162.3(7) and 160.8(7), which approximately corresponds with double bonds.

3·0.5CH2Cl2: Space group P4/n, Z = 2, lattice dimensions at 193 K: a = b = 1678.8(1), c = 1244.3(1) pm, R1 = 0.0618. 3·0.5CH2Cl2 contains [Sb(NPPh3)4]+ cations with tetrahedrally coordinated Sb atom and short Sb–N bond lengths of 193.7(6) pm. The PN distances of the phosphoraneiminato ligands, (NPPh3)− with 156.5(6) pm, correspond with double bonds, the SbNP bond angles are 130.6(3)°.
Zum thermochemischen Verhalten von Halogeniden, Oxidhalogeniden, Aluminiumhalogeniden und Ammoniumhalogeniden der Seltenerdelemente
Authors: Oppermann Heinrich , Schmidt Peer
Published: May 2005

Nach einer kritischen Sichtung zum thermischen Verhalten von Seltenerdhalogeniden LnX3, Seltenerdoxidhalogeniden LnOX, Seltenerdaluminiumhalogeniden LnmAlnX3(m+n) und Seltenerdammoniumhalogeniden (NH4)xLnyX3y+x werden die Bildungsenthalpien und Standardentropien ausgewertet und die empfohlenen Werte angegeben. Aus dem linearen Zusammenhang zwischen den Differenzen der Bildungsenthalpien von Seltenerdoxiden Ln2O3 und ‐halogeniden LnX3 bzw.‐oxidhalogeniden LnOX und dem Ionenradius der betreffenden Elemente werden die in der Literatur fehlenden Werte für einige Halogenide und Oxidhalogenide hergeleitet. Das Verdampfungs‐ und Sublimationsverhalten der LnX3 sowie das Zersetzungsverhalten der Verbindungen LnOX wird verallgemeinernd beschrieben und das Chemische Transportverhalten der LnX3 mit AlX3 systematisch eingeordnet. Die thermische Stabilität der Europiumtrihalogenide wird quantifiziert. Aus den bekannten Zustandsbarogrammen und Zustandsdiagrammen der Systeme Seltenerdtrihalogenid/Aluminiumhalogenid (LnX3/AlX3) und Ammoniumhalogenid (LnX3/NH4X) werden allgemeingültige Schlussfolgerungen für Systeme mit LnX3 gezogen.
Crystal Structure and Stablility of the Fullerene – Chalcogene Co‐Crystal C60Se8CS2
Authors: Panthöfer M. , Shopova D. , Jansen M.
Published: May 2005

C60Se8CS2 was prepared, for the first time, by slow concentration of a solution of C60 and Se8 in carbondisulfide. The crystal structure (P21/c, a = 1330.05(17), b = 2900.6(4), c = 988.09(13) pm, b = 91.760(2)°; Z = 4; 8910 independent reflections; R1 = 0.073; wR2 = 0.186) contains fully ordered fullerene molecules. It may be derived from the NiAs‐structure‐type with Se8‐rings and CS2 filling the octahedral voids of the distorted hexagonal close packing of fullerene molecules. The results are completed by Raman‐spectroscopic and thermogravimetric investigations.
Preparation and Crystal Structure of MnBiSe2I
Authors: Pfitzner Arno , Zabel Manfred , Rau Franz
Published: May 2005

Black single crystals of MnBiSe2I were obtained by the reaction of stoichiometric amounts of Mn, Bi, BiI3, and Se at 600 °C for 7 days. The compound crystallizes in the monoclinic system, space group C2/m, with a = 13.428(2), b = 4.112(1), c = 10.130(2) Å, β = 90.97(2)°, and Z = 4. The crystal structure refinement based on 849 reflections converged at R = 0.0380 and wR2 = 0.0916, respectively. MnBiSe2I forms a layer structure consisting of MnSe6 octahedra, MnSe2I4 octahedra, and BiSe3+2 pyramids.
Transmetallierung von Zinn(II) in [Sn(μ3‐PSitBu3)]4 durch Barium – von Sn4P4‐Heterocuban‐Strukturen zu heterobinuklearen Käfigverbindungen mit einem zentralen BanSn4−nP4‐Heterocuban‐Polyeder (n = 1, 2 und 3)
Authors: Westerhausen Matthias , Krofta Mathias , Schneiderbauer Stefan , Piotrowski Holger
Published: May 2005

Transmetallation of Tin(II) in [Sn(μ3‐PSitBu3)]4 by Barium – from Sn4P4 Heterocubane Structures to Heterobinuclear Cage Compounds with a Central BanSn4−nP4 Heterocubane Polyhedron (n = 1, 2 and 3)

For the preparation of compounds of the type [BanSn4−n(PSitBu3)4] (n = 1 (2), 2 (3) and 3 (4)) two synthetic routes are applicable: in the transmetallation reaction homometallic [Sn4(PSitBu3)4] (1) reacts with barium metal and in a deprotonation reaction (metallation) tri(tert‐butyl)silylphosphane reacts simultaneously with (thf)2Ba[N(SiMe3)2]2 and Sn[N(SiMe3)2]2. During the transmetallation reaction mixtures of the heterobimetallic cage compounds 2 to 4 are obtained, however, analytically pure compounds 2 and 3 are accessible by the metallation reaction. Compound 4 is formed as a minor product together with 3. Due to the larger Ba‐P bond lengths compared to the Sn‐P values the substitution of tin by barium leads to strong distortions of the heterocubane moiety. With NMR‐spectroscopic experiments one could show that all the above mentioned compounds form BanSn4−nP4 heterocubane cage structures.
Carbon mineralization by termites in tropical forests, with emphasis on fungus combs
Authors: Yamada Akinori , Inoue Tetsushi , Wiwatwitaya Decha , Ohkuma Moriya , Kudo Toshiaki , Abe Takuya , Sugimoto Atsuko
Published: May 2005

A role of termites in decomposition processes was quantitatively evaluated in a dry evergreen forest (DEF) in Thailand, using respiration rates and biomasses of fungus combs as well as of termites themselves. The termite population and fungus combs mineralized 11.2% of carbon (C) in the annual aboveground litterfall (AAL) by their respiration. Fungus combs were responsible for a major part (7.2% of the AAL) of the C mineralization mediated by termites. For comparison, fractions of AAL mineralized by respiration from termite populations and fungus combs were estimated for tropical forests and savannas where termites have been well studied, assuming that there is the same ratio as for the DEF between biomass of fungus combs and abundance of fungus growers. Termites in dry tropical forests (annual rainfall<2,000 mm) are shown to mineralize about 10% of C in the AAL by respiration from their populations and fungus combs, and their ecological impact in savannahs is comparable in this aspect. A significant negative correlation between fraction of AAL and annual rainfall demonstrates that the importance of termites in decomposition processes is greater in dry tropical forests than in moist tropical forests. Considering that fungus combs contributed significantly to AAL mineralization in most of the tropical forests and savannas, fungus growers are a much more influential group than previously expected in tropical ecosystems.
Evolution of cooperation in patchy habitat under patch decay and isolation
Authors: Zhang Feng , Hui Cang , Han Xiaozhuo , Li Zizhen
Published: May 2005

The spatial version of Prisoner's Dilemma (PD) is studied, which incorporates habitat decay through change in the mortality parameter and habitat isolation through change in the colonization coefficient. We found four kinds of evolutionary results, which are affected profoundly by the elements of the payoff matrix and the ratio of the colonization coefficient to the mortality parameter: population extinction, a pure cooperator population, coexistence of cooperators and defectors, and a pure defector population. First, the parameter region of cooperation (pure cooperator and coexistence region) shrinks with an increase in the cooperative cost, and that of defection extends. The increase in cooperative reward makes the cooperative region extend and the defector region become small. Second, the cooperative reward can compensate for the extinction risk due to habitat destruction and allow a population to survive even if the colonization coefficient is smaller than the mortality parameter. Third, although habitat destruction (including decay and isolation) increase the extinction risk of a population, moderate external power can push the evolution of cooperation ahead of population extinction, and even make a completely cooperative world come into being. Finally, for certain values of elements of the payoff matrix, the population suffering habitat destruction can maintain a stable population size by regulating the frequencies of cooperators and defectors. This implies that the multi‐behavior strategy within a population may be a mechanism to defend against the influences of a changing environment.
No diapause prolongation response of Daphnia in the presence of planktivorous mosquitofish (Gambusia holbrooki)
Authors: Angeler David G.
Published: May 2005

Recent research suggests that planktonic organisms in resting stages can perceive predators chemically and delay hatching to evade predation. Using a co‐occurring predator–prey pair (Gambusia holbrooki Girard and Daphnia curvirostris Eylmann) from a Mediterranean floodplain wetland, this study tested for such predator‐avoidance behaviour of Daphnia. Results show that hatching patterns of Daphnia were not reduced by the presence of different biomass levels of Gambusia. This could be due to the fact that the density of Gambusia in the wetland is high from late spring to late autumn, suggesting that delayed hatchlings would face increased mortality through consumptive predation.
Resveratrol–Cu(II) induced DNA breakage in human peripheral lymphocytes: Implications for anticancer properties
Authors: Azmi Asfar Sohail , Bhat Showket Hussain , Hadi S.M.
Published: May 2005

Resveratrol (3,4′,5‐trihydroxy stilbene), a plant derived polyphenol found in mulberries, grapes and red wine is considered to possess chemopreventive properties against cancer. It is recognized as a naturally occurring antioxidant but also catalyzes oxidative DNA degradation in vitro in the presence of transition metal ions such as copper. Using a cellular system of lymphocytes isolated from human peripheral blood and Comet assay, we have confirmed that resveratrol–Cu(II) system is indeed capable of causing DNA degradation in cells such as lymphocytes. Also, trans‐stilbene, which does not have any hydroxyl groups, is inactive in the lymphocyte system. Pre‐incubation of lymphocytes with resveratrol indicates that it is capable of either traversing the cell membrane or binding to it. Our results are in partial support of our hypothesis that anticancer properties of various plant derived polyphenols may involve mobilization of endogenous copper and the consequent prooxidant action.
Insulin and IGF‐1 regulate the expression of the pituitary tumor transforming gene (PTTG) in breast tumor cells
Authors: Thompson Alvin D. , Kakar Sham S.
Published: May 2005

The pituitary tumor transforming Gene (PTTG) is an oncogene that is highly expressed in most tumors analyzed to date. Here, we report the effects of insulin and the insulin like growth factor‐1 (IGF‐1) on the expression of PTTG. Using MCF‐7 cells, a human breast cancer cell line, we observed that both insulin and IGF‐1 upregulate the expression of PTTG mRNA by approximately 2.5‐fold. Induction of PTTG mRNA expression by insulin or IGF‐1 was completely blocked by the specific phosphatidylinositol (PI) 3 kinase inhibitor LY294002, but partially blocked by the MAP kinase inhibitor PD98059. Pretreatment of MCF‐7 cells with actinomycin D completely blocked the stimulatory effect of insulin. Transfection of MCF‐7 cells with a PTTG promoter‐luciferase reporter construct revealed the dose‐dependent stimulation of PTTG promoter activity by insulin, suggesting that the increase in PTTG expression by insulin is a result of activation of transcription of the PTTG gene. Taken together, our results suggest that insulin and IGF‐1 regulate the expression of PTTG in MCF‐7 cells primarily through the activation of PI3K/AKT cascade.
Distal Radioulnar Joint Incongruity After Shortening of the Ulna
Authors: DESHMUKH S. C. , SHANAHAN D. , COULTHARD D.
Published: May 2005

Coronal sections of the distal radioulnar joint (DRUJ) were studied in 13 preserved cadaveric wrists specimens before and after 2 mm of shortening of the ulna. The DRUJs were subclassified on the basis of the DRUJ angle and depth of the sigmoid notch. The changes in extent and location of area of contact and radioulnar separation were noted. Although reduction in area of contact occurred in every specimen and DRUJ type, the maximum radioulnar separation and reduction in area of contact occurred in the DRUJ type IB and IIB. This could be a possible factor producing point loading and subsequent occurrence of DRUJ remodelling in the long-term after shortening of the ulna.
Triggering mechanism at the origin of paroxysms at Stromboli (Aeolian Archipelago, Italy): The 5 April 2003 eruption
Authors: Métrich Nicole , Bertagnini Antonella , Landi Patrizia , Rosi Mauro , Belhadj Oulfa
Published: May 2005

The 5 April 2003 paroxysm of Stromboli occurred during an ongoing effusive episode that initiated on 28 December 2002. It mainly consisted in two, a few seconds apart cannon‐like explosions followed by a vertical gas/pyroclast jet. The HK‐basaltic pumices, that were generated, mainly contain crystals that were drained back from the shallow parts of the plumbing system. Few euhedral to anhedral olivines and their melt inclusions testify to crystal fractionation and possible mixing between HK‐basaltic magmas variable in their volatile content, extent of evolution and volume. The most primitive, volatile‐rich, HK‐basalt term is sizable at micrometer scale, only. We propose that the triggering mechanism of the paroxysm was initiated at moderate pressures (≥240 MPa) and was related to bubble‐driven ascent of magma blobs. The latter rose through and interacted with overlying slightly more evolved melts and, finally mingled with the shallow crystal‐rich magma just before the eruption.
Brittle‐ductile coupling: Role of ductile viscosity on brittle fracturing
Authors: Schueller Sylvie , Gueydan Frédéric , Davy Philippe
Published: May 2005

Localized or distributed deformations in continental lithosphere are supposed to be triggered by rheological contrasts, and particularly by brittle‐ductile coupling. A plane‐strain 2D finite‐element model is used to investigate the mechanical role of a ductile layer in defining the transition from localized to distributed fracturing in a brittle layer. The coupling is performed through the shortening of a Von Mises elasto‐visco‐plastic layer rimed by two ductile layers. By increasing the viscosity of the ductile layers by only one order of magnitude, the fracturing mode in the brittle layer evolves from localized (few faults) to distributed (numerous faults), defining a viscosity‐dependent fracturing mode. This brittle‐ductile coupling can be explained by the viscous resistance of the ductile layer to fault motion, which limits the maximum displacement rate along any fault connected to the ductile interface. An increase of the viscosity will thus make necessary new faults nucleation to accommodate the boundary shortening rate.
Variation of physical properties beneath a fault observed by a two‐ship seismic survey off southwest Japan
Authors: Tsuru Tetsuro , Miura Seiichi , Park Jin‐Oh , Ito Aki , Fujie Gou , Kaneda Yoshiyuki , No Tetsuo , Katayama Takeshi , Kasahara Junzo
Published: May 2005

We conducted a two‐ship seismic reflection survey at Kumano‐nada off the southwest Japan arc, in 2002, in order to clarify physical properties along a splay fault that branches from the plate boundary of the Nankai Trough subduction zone. During the survey, seismic reflection data were collected out to maximum offset of 20 km using multiple passes of a shooting and a receiving vessel separated by a different constant offset on each pass. We conducted analyses on reflection polarity and amplitude variation with offset (AVO) effects to examine physical properties of layers immediately beneath the splay fault. Reflections from the splay fault showed varying polarities along the fault. In the present study, we assumed that the Poisson's ratio of the layer above the fault was 0.30–0.40. Where polarity is reversed, the Poisson's ratio of the layer immediately below the fault was estimated to be 0.33–0.445 (11% increase on average). Where polarity was normal, the ratio was estimated to be 0.263–0.365 (11% decrease on average). If the reverse polarity indicates the existence of fluid as many authors suggest, the polarity analysis demonstrates inhomogeneous distribution of fluid in the splay fault shear zone. The results of AVO analysis also support the possibility of the spatial variation of fluid distribution under some assumptions because the Poisson's ratio changes with content of fluid in rocks. The variation in reflection polarity and corresponding AVO effects may signify the possibility of localized fluid migration in the splay fault shear zone.
Slip‐generated patterns of swarm microearthquakes from West Bohemia/Vogtland (central Europe): Evidence of their triggering mechanism?
Authors: Fischer Tomáš , Horálek Josef
Published: May 2005

We investigated space‐time relations between consecutive events of West Bohemian 2000 swarm and their association with the Coulomb stress changes induced on a fault plane by prior swarm events. A few thousand M ≤ 3.3 strike‐slip swarm earthquakes clustered along a fault plane at depths 6.5–10.5 km and showed common rake angle of 30°. In order to disclose earthquake interaction we investigated the space‐time relations between consecutive earthquakes. We determined relative position vectors for each consecutive event pair, the prior event and the immediate aftershock (IA), and we measured time lags between them. The resulting cluster of relative position vectors shows a high density of aftershocks near the origin, which decays with distance. It points out a triggering effect of the prior event upon subsequent aftershocks. The spatial distribution of the relative positions disclosed dominance of aftershocks in the slip‐parallel directions, which is manifested by pronounced elongation of the cluster of the relative positions and of the angular dependence of the rate of IAs. The temporal distribution of the relative positions indicates that some aftershocks prove high interevent velocities and occur systematically at greater distances, suggesting the existence of two distinct triggering mechanisms acting at large and small timescales. We evaluated the complete Coulomb stress change upon the fault plane due to the prior event and showed that the observed space‐time distribution of the relative positions can be explained by a common effect of both static and dynamic stress changes, which act on different distance and timescale.
Mean surface circulation and mesoscale turbulent flow characteristics in the eastern South Pacific from satellite tracked drifters
Authors: Chaigneau Alexis , Pizarro Oscar
Published: May 2005

Circulation of the eastern South Pacific region (10°–34°S, 70°–100°W) was studied using drifting buoy trajectories from 1979 to 2003. Three different current regimes were highlighted: the South Equatorial Current, flowing westward north of 26°S with surface velocities of 7–8 cm s−1; the South Pacific Current, an eastward current of ∼2 cm s−1 south of 25°–30°S; and the Chile‐Peru Current, a northwestward flow of ∼6 cm s−1 found to the east of 82°W and south of 22°S. The velocity variance distribution showed the regional flow to be anisotropic in nature. Maps of eddy kinetic energy obtained from drifter measurements and satellite altimetry data showed similar patterns, with higher energy levels near the South American coast. The Lagrangian time and length scales of the turbulent flow revealed typical values of 5.9 ± 0.6 days and 40.7 ± 5.4 km in the zonal direction and of 3.5 ± 0.4 days and 29 ± 3.4 km in the meridional direction. The estimated diffusivities were (4.9 ± 0.5) × 107 cm2 s−1 and (2.6 ± 0.3) × 107 cm2 s−1 in the eastward and northward directions, respectively. Finally, we estimated the respective role of horizontal advection and lateral diffusion on the mixed layer heat and salt budgets. Near the coast the lateral turbulent fluxes in the surface layer were two times larger than the horizontal transports associated with the large‐scale circulation; mean horizontal heat and salt diffusive fluxes were around 25 W m−2 and 50 g m−2 d−1.
Observations and scaling of the upper mixed layer in the North Atlantic
Authors: Lozovatsky I. , Figueroa M. , Roget E. , Fernando H. J. S. , Shapovalov S.
Published: May 2005

The dependence of the mixed layer depth hD on the sea surface fluxes is analyzed based on measurements taken along a cross‐Atlantic section 53°N. A linear function hD ≈ 0.44Lf, where Lf = u*/f is the Ekman scale, well represents the influence of the wind stress u* and rotation f on the mixed‐layer deepening, thus indicating that the influence of convective mixing in late spring at this latitude is of a lesser importance. Also, data showed reasonable correlation of hD with the stratified Ekman scale LfN = u*/, where Npc is the buoyancy frequency in the pycnocline, according to hD ≈ 1.9LfN. In both cases the highest correlation between hD and the corresponding lengthscales is achieved when u* values taken 12 hours in advance of the mixed layer measurements were used, which may signify the adjustment time of inertial oscillations to produce critical shear at the base of the mixed layer. The vertical profiles of the dissipation rate ɛ(z) are parameterized by two formulae that are based on the law of the wall scaling ɛs(z) = u*3/0.4z and the buoyancy flux Jb: ɛ1(z) = 2.6ɛs(z) + 0.6Jb and ɛ2(z) = ɛs(z) + 3.7Jb. The first parameterization is used to calculate the integrated dissipation int over the mixing layer, which was found to be ∼3–7% (5% on the average) of the wind work E10. The positive correlation between hD and int/E10 suggests that in deeper quasi‐homogeneous layers a larger portion of the wind work is consumed by viscous dissipation vis‐à‐vis that is used for entrainment. As such, the mixing efficiency, which is based on integral quantities, is expected to decrease with the growth of the mixed layer.
Initial leader velocities during intracloud lightning: Possible evidence for a runaway breakdown effect
Authors: Behnke Sonja A. , Thomas Ronald J. , Krehbiel Paul R. , Rison William
Published: May 2005

Using three‐dimensional lightning mapping observations, the initial leaders of intracloud flashes have been found to start at a median speed of about 1.6 × 105 m s−1 and to decelerate during the first 10–15 ms of the discharge. The results disagree with the predictions that the speed should increase with time as the developing leader shorts out an increasing potential difference in the storm. The observations can be explained if the flash initiation region is preconditioned in some manner to give a high initial speed and if the preconditioning decays with time and/or decreases with distance to give the observed speed decrease. Such preconditioning could be the result of ionization and excited molecules produced by energetic electron avalanches.
Ceres: Evolution and current state
Authors: McCord Thomas B. , Sotin Christophe
Published: May 2005

We modeled several thermal evolution scenarios for Ceres to explore the nature of large, wet protoplanets and to predict current‐day evidence that might be found by close inspection, such as by the Dawn mission. The density for Ceres is near 2.1, suggesting a water content between 17% and 27% by mass. Short‐ and long‐lived radioactive nuclide heating is considered. Even if only long‐lived radionuclide heating is assumed, the water ice in Ceres melts quickly and a water mantle forms, but an approximately 10‐km crust does not melt. The circulating warm water would alter the silicates. As heat is lost by conduction through the frozen crust, water begins to freeze out at the base of the crust. Solid‐state convection begins and transports more heat as well as perhaps material dissolved or entrained in the water to or near the surface. Ceres' water layer eventually (but perhaps not entirely) freezes, forming a layered density structure with perhaps some liquid water remaining today. Our differentiated models are in agreement with the recently measured difference between the equatorial and polar radii. We find that Ceres' existence and evolution depend critically on it containing water at formation, and this depends strongly on the combination of when it accreted and the amount of26Al present in the pre‐Ceres ∼1‐km‐sized objects; slightly more26Al or earlier accretion produces a dry Vesta‐like object. Melting and freezing plus mineralization would lead to several dimensional changes over time, creating topographic features, zones of weakness, and perhaps disruptions in the crust.
Origin of transverse ridges on the surfaces of catastrophic mass flow deposits on the Earth and Mars
Authors: Baloga S. M. , Bruno B. C.
Published: May 2005

Transverse ridges on the surfaces of catastrophic mass flow deposits such as landslides, debris flows, and lahars may be the remnants of surface waves that originated during transit. Such waves can form as a result of a flow instability or from irregularities or pulses in the release of material at the source. We first consider a steady state release of material into the flow. By considering classic fluid dynamic stability criteria, we show that flow instabilities known to lead to roll waves seem likely for the mass flow deposits studied on Earth and Mars. Motivated by the plausibility of dynamic wave formation, we consider the more realistic case of a time‐dependent release of material into the flow by performing a detailed mathematical analysis of the momentum and volume conservation equations. The results show that for some regimes of flow conditions, any disturbances in the source conditions grow downstream without bound, much like a classical fluid dynamic instability. It is conjectured that this regime may lead to analogs of roll waves. In other regimes, however, any irregularities in the boundary conditions at the source of the flow decay, as in a stable fluid flow. One critical parameter delineating the regimes of stability and instability is the time constant for the decay of the flow depth at the source. When surface waves are preserved in the deposits of long runout, catastrophic mass flows, our results provide a new diagnostic for constraining the emplacement conditions and the rheology of the flow during transit.
Effect of source and receiver radiation characteristics in subsurface prospecting within the distorted Born approximation
Authors: Soldovieri Francesco , Persico Raffaele , Leone Giovanni
Published: May 2005

Linear models are widely adopted in subsurface prospecting because of the advantages in terms of effectiveness and numerical efficiency. They make it possible to simplify the problem of inverse scattering and at the same time to obtain acceptable results in locating buried objects. In this paper, we deal with subsurface prospecting where a model linearization is performed via distorted Born approximation and considering a half‐space geometry in a two‐dimensional scalar problem within a multistatic/multiview configuration. In this realm, most inversion algorithms fail to take into account the radiation properties of both transmitting and receiving antennas. Our goal is thus twofold. First, we aim to provide an insight into the role played by the radiation properties of antennas on the quality of the reconstructed tomographic image of the investigated domain. This task is performed by first tackling the single‐frequency case in order to gain insight into the effect of the radiation pattern using simple arguments and then examining the multifrequency case. Numerical results confirm the theoretical expectation that the quality of the reconstruction gets worse for antennas with directive radiation patterns. Second, we numerically investigate the effects of inaccurate knowledge of the antenna pattern.
Miocene to Present differential exhumation in the Western Alps: Insights from fission track thermochronology
Authors: Malusà Marco G. , Polino Riccardo , Zattin Massimiliano , Bigazzi Giulio , Martin Silvana , Piana Fabrizio
Published: May 2005

Analysis of cooling age patterns yielded by low‐temperature thermochronometers provides key information about the role played by tectonic discontinuities during the late stages of exhumation of metamorphic belts. In the Western Alps, fission track data published so far are heterogeneously scattered and concentrated in few structural domains, preventing analyses at the scale of the whole belt. The new apatite fission track data reported in this work, obtained with the external detector method as well as the population method in very low U content samples, fill this gap. They constrain the postmetamorphic evolution of the Western Alps along two transects from the foreland to the retroforeland, unraveling the effective role played by some major faults during the exhumation of the belt at shallow crustal levels. A clear regional pattern, characterized by decreasing ages moving from the axial sector to the European external sector of the belt and by an along‐strike gradient with increasing ages from north to south, has been unraveled. Evident breaks in this age pattern have been detected in correspondence of faults that are near‐parallel to the trend of the belt, pointing to the occurrence of active tectonics during and after exhumation. The most apparent breaks have been observed in the axial sector of the belt, where the postmetamorphic deformation would have been negligible according to classic tectonic models. Faults located in the axial sector split the belt into two major blocks (eastern and western). Since the Miocene, the western block experienced higher exhumation rates than the eastern one. Such differential exhumation was accommodated in the northern portion of the belt thanks to reverse motion along the Internal Houiller Fault, which occurred in a convergent transcurrent framework. To the south, it was accommodated instead by normal reactivation of the Briançonnais Front and by activity of the Longitudinal Fault System, which occurred in a divergent transcurrent framework. The tectonic activity affecting the axial sector of the belt, in a context of regional dextral strike slip, is coeval with the forward propagation of the external thrusts, and of similar magnitude. We suggest that the contrasting kinematic regimes (i.e., convergent versus divergent transcurrence) observed in the Western Alps moving along strike were responsible of the increasing exhumation rates toward the north, revealed in both blocks by the along‐strike age gradient. The higher exhumation rates recognized northward would be related to an increasing importance of crustal shortening that promoted erosion during the late stages of exhumation of the belt.
Field‐scale experiments of unsaturated flow and solute transport in a heterogeneous porous medium
Authors: Nichol Craig , Smith Leslie , Beckie Roger
Published: May 2005

A multiyear flow and conservative tracer test has been carried out in unsaturated mine waste rock to examine the physical mechanisms by which water moves through this coarse, heterogeneous, granular material. The experimental system has a footprint of 8 m × 8 m, is 5 m high, and is built on a contiguous grid of 16 zero‐tension lysimeters. A chloride tracer was applied during a single rainfall event. Subsequently, the system has been subject to both natural and applied rainfall events in which no further tracer was added. Water flow and tracer transport is monitored using in situ measurements of moisture content, matric suction, and soil water solution samplers. Results demonstrate for transient infiltration conditions the influence and interaction of matrix flow in a heterogeneous granular matrix, preferential flow in macropores, and noncapillary pathways. Tracer migration through preferential flow paths dominates the initial and peak breakthrough concentrations. Point measurements of tracer concentration from in situ solution samplers yield a relatively poor indication of the flux‐averaged transport of mass that is recorded at the base of the experiment, in addition to overestimating the stored mass and underestimating residence time.
Streambed scour and fill in low‐order dryland channels
Authors: Powell D. Mark , Brazier Richard , Wainwright John , Parsons Anthony , Kaduk Jörg
Published: May 2005

Distributions of scour and fill depths recorded in three low‐order sand bed dryland rivers were compared with the Weibull, gamma, exponential, and lognormal probability density functions to determine which model best describes the reach‐scale variability in scour and fill. Goodness of fit tests confirm that the majority of scour distributions conform to the one‐parameter exponential model at the 95% significance level. The positive relationship between exponential model parameters and flow strength provides a means to estimate streambed scour depths, at least to a first approximation, in comparable streams. In contrast, the majority of the fill distributions do not conform to the exponential model even though depths of scour and fill are broadly similar. The disparities between the distributions of scour and fill raise questions about notions of channel equilibrium and about the role of scour and fill in effecting channel change.
Evidence for non‐constant energy/moment scaling from coda‐derived source spectra
Authors: Mayeda Kevin , Gök Rengin , Walter William R. , Hofstetter Abraham
Published: May 2005

We present two lines of evidence showing the ratio of seismically radiated energy (ER) to seismic moment (Mo) increases with increasing moment for crustal events spanning 5 orders in seismic moment. This ratio, often referred to as the scaled energy (=ER/M0) has been elusive and the subject of recent debate within the seismological community. Because significant frequency‐dependent corrections must be made to account for source and path heterogeneity, it is not uncommon that energy estimates of the same event by different researchers have significantly different values. To minimize some of the potential problems, we used the regional coda methodology outlined by Mayeda et al. (2003) on 4 large earthquake sequences; Mw 7.4 and 7.2 Izmit/Duzce, Mw 7.2 Gulf of Aqaba, Mw 7.3 Landers, and Mw 7.2 Hector Mine. This methodology has been shown to provide the lowest variance estimate of the source spectrum when compared against traditional direct wave estimates. In our first approach we made energy estimates from coda‐derived spectra and observed that increases with increasing moment for 3.7 ≤ Mw ≤ 7.4. In our second approach we used the simple idea outlined by Prieto et al. (2004) to directly test for self similarity. Under self similarity, earthquake source spectra scaled by ω−3 should have the same shape. To test this, one needs very stable spectra either through spectral stacking of direct wave spectra or by the use of stable coda‐derived spectra. For all sequences we found that the mainshocks and larger aftershocks had significantly different spectral shapes than the smaller events. The scaled ω−3 spectra of the larger events represented an upper bound, having larger amplitudes near the corner frequency. In fact, an ω−3.5 scaling moved the larger events closer to the mean of the spectral population, though the spectral shape differences persisted. These results strongly suggest that earthquakes are not scaling self‐similarly and that complexities in the rupture process such as variable slip velocity exist between small and large events.
Detection of triggered deep low‐frequency events from the 2003 Tokachi‐oki earthquake
Authors: Miyazawa Masatoshi , Mori Jim
Published: May 2005

We show the level of increased/decreased seismicity mapped across Japan immediately following the 2003 Tokachi‐oki earthquake (Mw 8.1) of September 25, 2003 (UT) by use of the β‐statistic. Significant dynamic triggering of events is found near the Nankai subduction zone 900–1400 km from the earthquake. The events are inferred to be dynamically triggered deep low‐frequency earthquakes, of a type that often occur in this region. The triggering appears to be caused by the long‐period oscillations of the surface waves, which may be effective in triggering fluid‐related events. The region that showed the highest level of triggered events, was an area of elevated activity in the Bungo strait where a slow‐slip event was in progress.
Using shear wave splitting measurements to investigate the upper mantle anisotropy beneath the North China Craton: Distinct variation from east to west
Authors: Zhao Liang , Zheng Tianyu
Published: May 2005

A compilation of shear wave splitting measurements in the North China Craton (NCC) is presented to investigate the upper mantle anisotropy beneath the region. By applying the method of Silver and Chan (1991), the splitting parameters of fast polarization direction and delay time are determined from SKS waveforms for 38 broadband stations. The results reveal the presence of small to large seismic anisotropy in the mantle beneath the NCC. The most striking result is the distinct difference of fast polarization directions between the Eastern Block (EB) and the Central Zone (CZ) of the NCC. The fast polarization directions trend SE beneath the EB, which implies that northwestward mantle flow has played a significant role in the reactivating of the EB during Late Mesozoic to Early Cenozoic, and the boundary between the CZ and the EB was possibly a west limit where the mantle flow was deflected. However, a collision event occurred in Early Proterozoic was also a possible cause for the anisotropy of the lithosphere beneath the CZ, depending on the craton lithosphere beneath the region had not been completely reformed by later tectonic activities.
Observations of premonitory acoustic emission and slip nucleation during a stick slip experiment in smooth faulted Westerly granite
Authors: Thompson Ben D. , Young R. Paul , Lockner David A.
Published: May 2005

To investigate laboratory earthquakes, stick‐slip events were induced on a saw‐cut Westerly granite sample by triaxial loading at 150 MPa confining pressure. Acoustic emissions (AE) were monitored using an innovative continuous waveform recorder. The first motion of each stick slip was recorded as a large‐amplitude AE signal. These events source locate onto the saw‐cut fault plane, implying that they represent the nucleation sites of the dynamic failure stick‐slip events. The precise location of nucleation varied between events and was probably controlled by heterogeneity of stress or surface conditions on the fault. The initial nucleation diameter of each dynamic instability was inferred to be less than 3 mm. A small number of AE were recorded prior to each macro slip event. For the second and third slip events, premonitory AE source mechanisms mimic the large scale fault plane geometry.
Fluid lava flows in Gusev crater, Mars
Authors: Greeley Ronald , Foing Bernard H. , McSween Harry Y. , Neukum Gerhard , Pinet Patrick , van Kan Mirjam , Werner Stephanie C. , Williams David A. , Zegers Tanja E.
Published: May 2005

Rocks on the floor of Gusev crater are basaltic in composition, as determined from measurements by the Mars Exploration Rover, Spirit. On the basis of compositional data, models of the basaltic lavas at the time of their emplacement suggest viscosities of 2.3 to 50 Pa · s (dependent on the number of phenocrysts and vesicles that were present), which would be more fluid than terrestrial tholeiitic lavas and comparable to mare lavas on the Moon or Archean high‐Mg basalts on Earth. Morphological data and crater counts derived from the High Resolution Stereo Camera on Mars Express and other orbiters suggest that the lavas flooded Gusev crater at about 3.65 b.y. and postdate older floor materials, such as putative sediments emplaced by Ma'adim Vallis.
Do mammalian cytochrome P450s show multiple ligand access pathways and ligand channelling?
Authors: Schleinkofer Karin , Sudarko  , Winn Peter J , Lüdemann Susanne K , Wade Rebecca C
Published: May 2005

Understanding substrate binding and product release in cytochrome P450 (CYP) enzymes is important for explaining their key role in drug metabolism, toxicity, xenobiotic degradation and biosynthesis. Here, molecular simulations of substrate and product exit from the buried active site of a mammalian P450, the microsomal CYP2C5, identified a dominant exit channel, termed pathway (pw) 2c. Previous simulations with soluble bacterial P450s showed a different dominant egress channel, pw2a. Combining these, we propose two mechanisms in CYP2C5: (i) a one‐way route by which lipophilic substrates access the enzyme from the membrane by pw2a and hydroxylated products egress along pw2c; and (ii) a two‐way route for access and egress, along pw2c, for soluble compounds. The proposed differences in substrate access and product egress routes between membrane‐bound mammalian P450s and soluble bacterial P450s highlight the adaptability of the P450 fold to the requirements of differing cellular locations and substrate specificity profiles.
Acetylcholine receptor channel subtype directs the innervation pattern of skeletal muscle
Authors: Koenen Michael , Peter Christoph , Villarroel Alfredo , Witzemann Veit , Sakmann Bert
Published: May 2005

Acetylcholine receptors (AChRs) mediate synaptic transmission at the neuromuscular junction, and structural and functional analysis has assigned distinct functions to the fetal (α2βγδ) and adult types of AChR (α2βεδ). Mice lacking the ε‐subunit gene die prematurely, showing that the adult type is essential for maintenance of neuromuscular synapses in adult muscle. It has been suggested that the fetally and neonatally expressed AChRs are crucial for muscle differentiation and for the formation of the neuromuscular synapses. Here, we show that substitution of the fetal‐type AChR with an adult‐type AChR preserves myoblast fusion, muscle and end‐plate differentiation, whereas it substantially alters the innervation pattern of muscle by the motor nerve. Mutant mice form functional neuromuscular synapses outside the central, narrow end‐plate band region in the diaphragm, with synapses scattered over a wider muscle territory. We suggest that one function of the fetal type of AChR is to ensure an orderly innervation pattern of skeletal muscle.
Activation of IKK by thymosin α1 requires the TRAF6 signalling pathway
Authors: Zhang Ping , Chan Justin , Dragoi Ana‐Maria , Gong Xing , Ivanov Stanimir , Li Zhi‐Wei , Chuang Tsheng , Tuthill Cynthia , Wan Yinsheng , Karin Michael , Chu Wen‐Ming
Published: May 2005

Thymosin α1 (Tα1) is noted for its immunomodulatory activities and therapeutic potential in treatment of infectious diseases and cancer. However, the molecular mechanism of its effectiveness is not completely understood. Here, we report that Tα1 induces interleukin (IL)‐6 expression through the IκB kinase (IKK) and nuclear factor‐κB (NF‐κB) pathway. Using IKKβ‐deficient bone‐marrow‐derived macrophages and mouse embryo fibroblasts (MEFs), we show that IKKβ is essential for IKK and NF‐κB activation as well as efficient IL‐6 induction. Further analysis using tumour necrosis factor receptor‐associated factor 6 (TRAF6)‐deficient MEFs shows that TRAF6 is crucial for activation of IKK and induction of IL‐6 by Tα1. Intriguingly, Tα1 triggers protein kinase C (PKC)ι/ζ activation, which is TRAF6 dependent and involves IKK. In addition, Tα1 induces the formation of a signalsome composed of TRAF6, p62 and PKCι/ζ as well as IKK. Thus, our study identifies Tα1 as a unique activator of the TRAF6 signal pathway and provides a cohesive interpretation of the molecular basis of the therapeutic utility of Tα1.
Spin transport in a Mn-doped ZnSe asymmetric tunnel structure
Authors: Papp G. , Borza S. , Peeters F. M.
Published: May 2005

Spin-dependent tunneling of electrons in a diluted magnetic semiconductor ZnSe∕Zn1−xMnxSe∕Zn1−yMnySe∕ZnSe∕Zn1−xMnxSe∕ZnSe heterostructure is investigated theoretically in the presence of parallel magnetic and electric fields, but our modeling is appropriate for any dilute magnetic II-VI semiconductor system. In the studied asymmetric system the transmission of electrons and the degree of spin polarization depend on the strength of the magnetic and electric fields and on the direction of the applied bias. For suitable magnetic fields, the output current of the system exhibits a nearly 100% spin polarization and the device can be used as a spin filter.
Effects of particle size and spacing on the optical properties of gold nanocrystals in alumina
Authors: Wang Juan , Lau W. M. , Li Quan
Published: May 2005

Au-particle/Al2O3-matrix nanocomposite thin films with a narrow Au particle size distribution were fabricated by radio-frequency magnetron cosputtering. The films were characterized both chemically and structurally using x-ray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy. The optical absorption of samples with various Au particle sizes and concentrations were measured using an ultraviolet/visible-spectrometer. Both the Au nanoparticle size and the Au concentration increase result in a redshift of the Au surface-plasmon resonance energy. The redshift due to the size effect is concluded as mainly originating from the size-dependent dielectric function of Au core electrons and a semiquantitative description of its size dependence is presented. The experimental result describing the concentration effect suggests a deviation from the conventional Maxwell-Garnett effective medium theory, which can be corrected by introducing the multipole effect based on the dipole-dipole interaction model.
A study of current transport in (BaxSr1−x)Ti1+yO3+z thin-film capacitors containing a voltage-dependent interface state charge distribution
Authors: Baniecki J. D. , Shioga T. , Kurihara K. , Kamehara N.
Published: May 2005

J – V – T characteristics, measured over a very wide temperature (50–441 K) range, are analyzed simultaneously with C–V measurements to investigate conduction mechanisms and the state of charge of Pt/BaxSr1−xTi1+yO3+z(BST)/Pt thin-film capacitors during an applied voltage or current stress. A time- and voltage-dependent state of charge of the Pt/BST/Pt capacitors is inferred from stress-induced voltage shifts in the C–V curves. The voltage and temperature dependence of the C–V curve shifts is shown to be consistent with a voltage-dependent charge in interface states resulting from a change in potential across interfacial dipole layers. An intimate contact Schottky barrier model incorporating a voltage-dependent charge in interface states at both cathode and anode contacts is used to investigate conduction mechanisms in Pt/BST/Pt thin-film capacitors. The basic transport mechanisms of drift-diffusion, thermionic field emission, and Fowler–Nordeim tunneling are shown to dominate leakage in limiting voltage and temperature regimes. Thermionic emission is not predicted to control current flow at any investigated voltage and temperature.