bluuebunny/crossref_metadata_2025 huggingface dataset:
CF Bond Cleavage during Derivatization Reactions of Amino Groups with TFBA and PFB at Plasma‐Processed Organic Surfaces?
Authors: Yegen Eda , Zimmermann Uwe , Unger Wolfgang E. S , Braun Thomas
Published: November 2008

Chemical derivatization XPS is used for the quantitative determination of amines at conventional organic surfaces, and it is also applied to plasma‐processed aminated surfaces. When using TFBA and PFB as derivatization reagents for tagging primary amino groups, unexpected fluorine species were observed in the second case. The existence of reaction pathways other than those expected for amine derivatization with PFB or TFBA has to be assumed. This phenomenon is tentatively interpreted as the result of CF bond cleavage during derivatization reactions of TFBA and PFB at plasma‐polymerized allylamine and other plasma‐processed aminated surfaces. As a consequence, quantification procedures based on derivatization by PFB or TFBA will underestimate amine surface concentrations.

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Fabrication of MgZnO films by molecular precursor method and their application to UV‐transparent electrodes
Authors: Mashiyama Yoshihiro , Yoshioka Kaori , Komiyama Shigetoshi , Nomura Hirohisa , Adachi Shunsuke , Sato Mitsunobu , Honda Tohru
Published: November 2008

MgZnO thin films were fabricated by the molecular precursor method (MPM) for the realization of cost‐effective near‐ultraviolet (UV) transparent electrodes for GaN‐based UV light‐emitting diodes (LEDs). The fabrication by MPM requires a common solution. It was clarified that ammonia aqueous is a common solvent for Mg, Zn and Ga precursors. MgZnO thin film was successfully fabricated on a quartz glass substrate using MgZnO precursor solution. The solid phase composition of Mg in the film is 40‐50% of its molar fraction in the liquid phase. The X‐ray diffraction patterns indicate the films have a hexagonal single phase, the same as in the case of ZnO. Ga doping of the MgZnO films enables their resistivity control. The possibility of applying MgZnO films for UV transparent electrodes on GaN‐based UV LEDs is discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface diffusion during metalorganic vapor phase epitaxy of AlN
Authors: Banal Ryan G. , Funato Mitsuru , Kawakami Yoichi
Published: November 2008

The surface diffusion of Al adatoms during metalorganic vapor phase epitaxy of AlN was investigated, using sapphire substrates with different mis‐orientations. It was found that the diffusion length during modified migration‐enhanced epitaxy (MEE) is about 40 nm and comparable to that of conventional MEE under the current growth conditions. The enhancement of the diffusion length by alternating supply of source precursors was also demonstrated. The screw dislocation density in the modified‐MEE‐grown AlN was extracted to be as low as 2.2 × 106 /cm2 from X‐ray diffraction, while the chemical etching by KOH solution revealed an etch pit density of 1.0 × 106 /cm2, both of which indicated its superior structural properties. The chemical etching also evidenced that the grown AlN has Al polarity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure effects on the structural, electronic, and optical properties of Sin@SWCNTs
Authors: Zhang Y. H. , Meng J. , Zhang X. Q. , Li Hui , Taft C. A.
Published: November 2008

Well‐ordered single, double/four parallel, three/four‐strands helical chains, and five‐strand helical chain with a single atom chain at the center of Si nanowires (NWs) inside single‐walled carbon nanotubes (Sin@SWCNTs) are obtained by means of molecular dynamics. On the basis of these optimized structures, the structural evolution of Sin@SWCNTs subjected to axial stress at low temperature is also investigated. Interestingly, the double parallel chains depart at the center and transform into two perpendicular parts, the helical shell transformed into chain, and the strand number of Si NWs increases during the stress load. Through analyzis of pair correlation function (PCF), the density of states (DOS), and the z‐axis polarized absorption spectra of Sin@SWCNTs, we find that the behavior of Sin@SWCNTs under stress strongly depends on SWCNTs' symmetry, diameter, as well as the shape of NWs, which provide valuable information for potential application in high pressure cases such as seabed cable. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Accurate solutions for the spiked oscillators
Authors: Campoy G. , Aquino N.
Published: November 2008

The one‐dimensional harmonic oscillator potential plus a term of the form λ / xα is known as the spiked oscillator potential; it constitutes a very interesting system because of its difficulties to accept perturbative and variational solutions for certain regimes of the α parameter. By the use of a numerical method, we obtain accurate energy eigenvalues and eigenfunctions for a wide range of λ values and a few α values. The accuracy of the present results is by much higher than previously published results. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Regionalization of natural flow regime: application to environmental flow optimization at ungauged sites
Authors: Shiau Jenq‐Tzong , Wu Fu‐Chun
Published: November 2008

In this work we use the regionalization approach (RA) to derive the natural flow regime at an ungauged site. The derived natural flow regime, expressed by the regional cdf models of 32 indicators of hydrologic alteration (IHA) is used in the histogram matching approach (HMA) to seek the optimal environmental flows for a proposed multiobjective diversion weir in Taiwan. The results reveal that the outcomes associated with the planning constant scheme are significantly improved by the optimal time‐varying scheme. The histogram dissimilarities of 32 IHA associated with the planning scheme are consistently greater than those associated with the optimal scheme, especially for low‐flow IHA. Despite the inherent discrepancy between different approaches to generating flow data at the ungauged site, the optimal outcomes resulting from the RA‐based natural flow regime appear to be plausible and consistent with those reported in the previous work, thus validating the RA used in this work. We also explore the effect of weighting factors on the optimal outcomes. The results reveal that the weighting factor of the ecosystem needs objective dominates all optimal outcomes, while those of the agricultural demands and interbasin transfers objectives have minor effects on the optimal outcomes. The global optimal solution is obtained with a full or null weighting assigned to the ecosystem needs objective, while the least optimal solution is obtained as the interbasin transfers objective is given a null weighting and the agricultural demands objective is weighted more than the ecosystem needs objective. River managers and decision makers may select more balanced weir operation strategies based on the results presented in this work. Copyright © 2008 John Wiley & Sons, Ltd.
Study on channel depletion in metal‐oxide‐semiconductor field effect transistor using top‐view imaging through scanning capacitance microscopy
Authors: Naitou Y. , Ogiso H. , Kamohara S. , Yano F. , Nishida A.
Published: November 2008

Carrier profiles within the near‐surface channel region of n‐type metal‐oxide‐semiconductor field‐effect transistors (n‐MOSFETs) have been examined using scanning capacitance microscopy (SCM). After the removal of a poly‐Si gate electrode, we were able to assess the qualitative local carrier concentration within specified regions of an n‐MOSFET using static capacitance (dC/dZ) measurement with its bias dependence (dC/dZ–V spectra). We found that the dC/dZ‐signal at the center of the channel region lowers as the gate length is reduced. This result is attributed to the carrier depletion within the channel, which is consistent with the threshold voltage (Vth) characteristics of the device properties. Copyright © 2008 John Wiley & Sons, Ltd.
Kupferchalkogenid‐Clusterverbindungen mit nitro‐funktionalisierter Ligandenhülle
Authors: Fernandez‐Recio Lucia , Fenske Dieter , Fuhr Olaf
Published: November 2008

Copper Chalcogenide Cluster Compounds with Nitro‐functionalized Ligand Shell

Three new copper chalcogenide cluster molecules, [Cu4(SC6H4NO2)4(PPh3)4] (1), [Cu4(SC6H4NO2)2(OAc)2(PPh3)4] (2), and [Cu22Se6(SC6H4NO2)10(PPh3)8] (3), have been synthesized and characterized by single crystal X‐ray structure analysis. 1 and 2 were prepared from the reactions of Cu(OAc) and HSC6H4NO2 in the presence of PPh3 and have a similar “chair” structure in which two copper atoms are trigonally coordinated and two are tetrahedrally coordinated. The nitro groups of the ligands are not coordinated to any metal atom, but are located on the surface of the organic shell of the cluster molecules. In a further reaction between 2 and Se(SiMe3)2, cluster 3 was crystallized. Crystals of 3 include approximately 16.5 molecules THF per formula unit. This synthesis demonstrates the use of these “small” copper chalcogenide clusters as precursor compounds for the synthesis of bigger species. Non‐functionalized compounds similar to 1 and 2 are typically very pale or even colourless crystals. This is in contrast to the clusters presented in this work, which formed intensively orange or red crystals, due to the presence of the nitro groups. To investigate the influence of these nitro groups on the optical properties in more detail we have carried out UV‐VIS spectroscopic measurements.
On an Unexpected 2D‐linked Rare Earth 1,2,4‐Triazolate Network: Synthesis, Crystal Structure, Spectroscopic and Thermal Properties of $_{\infty}^{2}\rm [Ho(Tz)_{3}(TzH)_{2}]TzH$
Authors: Müller‐Buschbaum Klaus , Mokaddem Yassin , Höller Christoph J.
Published: November 2008

The network compound $_{\infty}^{2}\rm [Ho(Tz)_{3}(TzH)_{2}]TzH$, (Tz− = 1,2,4‐triazolate anion, C2H2N3−, TzH = 1,2,4‐1H‐triazole, C2H3N3), was obtained as pink single crystals by the reaction of the holmium metal with a melt of the amine 1,2,4‐1H‐triazole. No additional solvent was used. The compound is an unexpected example of a 2D‐linked network structure as other lanthanides give 3D‐frameworks and MOFs with 1,2,4‐1H‐triazole instead. This illustrates that the series of lanthanides yields very different results in attempts to create MOF structures. In $_{\infty}^{2}\rm [Ho(Tz)_{3}(TzH)_{2}]TzH$ the triazolate ligands Tz− function both as μ‐η1:η2 linkers as well as η1 end on ligands. The latter coordination mode is also found for additional triazole molecules. C.N. is nine for holmium(III). The layers $_{\infty}^{2}\rm [Ho(Tz)_{3}(TzH)_{2}]$ exhibit a system of intra and inter layer hydrogen bonding and to triazole molecules from the melt reaction intercalated in‐between the layers. The product was investigated by X‐ray single crystal analysis, Mid IR, Far IR and Raman spectroscopy, and with DTA/TG regarding its thermal behaviour.
Lanthanoidkomplexe von 1‐(2‐Propenyl)‐ und 1‐(3‐Butenyl)‐1,4,7,10‐tetraazacyclododecan‐4,7,10‐triessigsäure
Authors: Schumann Herbert , Kuse Katharina
Published: November 2008

η3‐1,4,7,10‐tetraazacyclododecane molybdenum tricarbonyl reacts with allyl bromide and 3‐butenyl bromide in dimethylformamide in the presence of K2CO3yielding 1‐(2‐propenyl)‐1,4,7,10‐tetraazacyclododecane (1a) and 1‐(3‐butenyl)‐1,4,7,10‐tetraazacyclododecane (1b), which on their part react with bromoacetic acidtert‐butyl ester in CH3CN to give 1‐(2‐propenyl)‐1,4,7,10‐tetraazacyclododecane‐4,7,10‐tris‐acetic acidtert‐butyl ester (2a) and 1‐(3‐butenyl)‐1,4,7,10‐tetraazacyclododecane‐4,7,10‐tris‐acetic acidtert‐butyl ester (2b), respectively. Compounds2aand2bare converted into the corresponding acids 1‐(2‐propenyl)‐1,4,7,10‐tetraazacyclododecane‐4,7,10‐tris‐acetic acid (4a) (MPC) and 1‐(3‐butenyl)‐1,4,7,10‐tetraazacyclododecane‐4,7,10‐tris‐acetic acid (4b) (MBC) via the trifluoroacetates3aand3b. Sm(NO3)3(H2O)6, LuCl3(THF)3, and TmCl3(H2O)6react with4aand4bforming the lanthanide complexes Sm(MPC) (5), Lu(MPC) (6), Tm(MPC) (7a) and Tm(MBC) (7b). The IR as well as the1H and13C NMR spectra of the new compounds are reported and discussed.
Pb(18‐crown‐6)Cl2 and Hg(18‐crown‐6)I2: Molecular Dihalides Trapped in a Crown Ether
Authors: Rieger Franziska , Mudring Anja‐Verena
Published: November 2008

Pb(18‐crown‐6)Cl2 and Hg(18‐crown‐6)I2 are obtained as transparent colourless crystals of needle and hexagonal shape, respectively, by isothermal evaporation of their dichloromethane solutions. Pb(18‐crown‐6)Cl2 crystallizes with the trigonal crystal system [$R{\bar 3}$, no. 148, a = b = 1176.3(2), c = 1191.8(3) pm, V = 1428.2(5) 106·pm3, Z = 3] whereas Hg(18‐crown‐6)I2 crystallizes with the orthorhombic crystal system (Pnma, no. 62, a = 1613.9(2) pm, b = 2822.2(5) pm, c = 841.3(1) pm, V = 3832(1)106·pm3, Z = 8). Both compounds are characterized by linear MX2 (HgI2 or PbCl2) molecular units which are encrypted by the crown ether. In both cases, the divalent metal ion resides in the middle of the crown ether resulting in a hexagonal bipyramidal coordination environment for the metal cations. The molecular symmetry comes close to D3d. Hg(18‐crown‐6)I2 and Pb(18‐crown‐6)Cl2 differ in the way the single MX2@18‐crown‐6 units are packed. Whereas the Hg(18‐crown‐6)I2 molecules are arranged in a (distorted) cubic closest packing, the Pb(18‐crown‐6)Cl2 molecules adopt a hexagonal closest packing.
Beiträge zur Kristallchemie und zum thermischen Verhalten von wasserfreien Phosphaten. XXXXII Die ersten Iridiumphosphate
Authors: Panagiotidis K. , Glaum R. , Hoffbauer W. , Weber J. , Schmedt auf der Günne J.
Published: November 2008

The First Iridiumphosphates

Two polymorphs of iridium(III)‐metaphosphate Ir(PO3)3 and an iridium(IV)‐silicophosphate (Ir1−xSix)3[Si2O(PO4)6] (x ∼ 0.5) were synthesized and their crystal structures determined from single‐crystal x‐ray data. Pale pink needles of triclinic Ir(PO3)3 (Ru(PO3)3 structure type, $P{\bar 1}$ (No. 2), Z = 2, a = 6.9574(6) Å, b = 10.3628(9) Å, c = 5.0288(4) Å, α = 92.28(1)°, β = 92.80(1)°, γ = 98.60(1)°, 1574 independent reflections, 122 parameters, R1 = 0.028, wR2 = 0.061) were grown from a metaphosphoric acid melt. Pale pink prisms of C‐type Ir(PO3)3 (C‐Al(PO3)3 structure type, Cc (No. 14), Z = 12, a = 13.103(2) Å, b = 19.183(1) Å, c = 9.354(1) Å, β = 127.19(1)°, 4254 independent reflections, 354 parameter, R1 = 0.024, wR2 = 0.062) were obtained by chemical vapour transport (900 °C → 800 °C, addition of IrCl3·xH2O). Both metaphosphates are built of [IrIIIO6] octahedra and infinite $^{1}_{\infty}\rm (PO^{-}_{3})$ chains. The latter have a translation period of three phosphate tetrahedra in the triclinic modification and six in the monoclinic. 1D and double‐quantum filtered 2D 31P‐MAS‐NMR spectra of C‐type Ir(PO3)3 confirm the chain structure and reveal a chemical shift range between −4,8 and −30,9 ppm for the 9 crystallographically independent, however chemically similar phosphate groups.

Pale orange crystals of (Ir1−xSix)3[Si2O(PO4)6] (Si3[Si2O(PO4)6] structure type, $R{\bar 3}$ (No. 148), Z = 3, a = 7.8819(8) Å, c = 24.476(4) Å, 1086 independent reflections, 56 parameters, R1 = 0.061, wR2 = 0.190) occurred in chemical vapour transport experiments aiming at the crystallization of C‐Ir(PO3)3. The crystal structure of the silicophosphate consists of isolated [IrIVO6] octahedra and [Si2O(PO4)6]12− heteropolyanions.
Zinc and Cobalt Complexes Derived from Tetradentate Tripodal Ligands with N2O2 Donorset as Model Compounds for Phosphatases
Authors: Schnieders David , Hammerschmidt Adrienne , Merkel Michael , Schweppe Florian , Krebs Bernt
Published: November 2008

Starting from the tripodal tetradentate ligands ‐(3,5‐dibromo‐2‐hydroxybenzyl)(2‐hydroxybenzyl)(2‐pyridyl)methylamine (H2L1), (3,5‐dibromo‐2‐hydroxybenzyl)(2‐hydroxy‐5‐nitrobenzyl)(2‐pyridyl)methylamine (H2L2), and (3,5‐dichloro2‐hydroxybenzyl)(2‐hydroxy‐5‐nitrobenzyl)(2‐pyridyl)methylamine (H2L3) the new isostructural dinuclear zinc compounds [Zn2(L1)2]·N(CH2CH3)3 (1), [Zn2(L2)2]·2CH3OH (2) and [Zn2(L3)2]·C4H10O (3) were synthesized. Due to their enzyme‐like trigonal bipyramidal N2O3 coordination environment of the zinc ions and the similar Zn···Zn distances the complexes can be considered to be structural models for the active sites in phospholipase C and nuclease P1. With H2L3 also the dinuclear complex [Co2(L2)2(CH3OH)]·2CH3OH·0.5C4H10O (4) could be prepared.

The new compounds were isolated and characterized by single crystal X‐ray crystallography as well as infrared spectroscopy. The cobalt compound 4 was additionally characterized by UV‐Vis spectroscopy and magnetic measurements. 1 crystallizes in the monoclinic space group P21/n with a = 11.2814(2), b = 28.6154(2), c = 13.1866(3) Å, β = 96.995(1)°, V = 4225.2(2) Å3, Z = 4. 2 and 3 are monoclinic, space group C2/c with a = 23.084(5), b = 9.232(2), c = 21.849(4) Å, &β; = 96.83(3)°, V = 4623(2) Å3, Z = 4, and a = 22.7834(3), b = 9.2463(1), c = 21.6351(3) Å, &β; = 97.592(1)°, V = 4517.7(2) Å3, Z = 4, respectively. 4 crystallizes in the monoclinic space group I2/a with a = 22.4680(4), b = 20.5517(4), c = 22.8910(6) Å, &β; = 111.938(1)°, V = 9804.7(4) Å3, Z = 8. 4 shows an effective magnetic moment of 6.72 μB at 300 K which clearly indicates the presence of two cobalt(II) high spin ions with Curie‐Weiss behaviour above 80 K. At lower temperatures a decrease of the effective magnetic moment was observed.
Fatty Acid Binding Domain Mediated Conjugation of Ultrafine Magnetic Nanoparticles with Albumin Protein
Authors: Bora DK , Deb P
Published: November 2008

A novel bioconjugate of stearic acid capped maghemite nanoparticle (γ-Fe2O3) with bovine serum albumin (BSA) was developed by taking recourse to the fatty acid binding property of the protein. From FT-IR study, it was found that conjugation took place covalently between the amine group of protein molecule and carboxyl group of stearic acid capped maghemite nanoparticle. TEM study further signified the morphology of the proposed nanobioconjuagte. The binding constant of nanoparticle with protein molecule was evaluated from the optical property studies. Also, magnetic measurement (M–H) showed retaining of magnetic property by significant values of saturation magnetization and other hysteretic parameters.
Periodic Mesoporous Organosilica Nanorice
Authors: Mohanty Paritosh , Landskron Kai
Published: November 2008

A periodic mesoporous organosilica (PMO) with nanorice morphology was successfully synthesized by a template assisted sol–gel method using a chain-type precursor. The PMO is composed of D and T sites in the ratio 1:2. The obtained mesoporous nanorice has a surface area of 753 m2 g−1, one-dimensional channels, and a narrow pore size distribution centered at 4.3 nm. The nanorice particles have a length of ca. 600 nm and width of ca. 200 nm.
On the Concept of a Morally Relevant Harm
Authors: LEFKOWITZ DAVID
Published: November 2008

The author argues that only when the two harms are morally relevant to one another may an agent take into account the number of people he can save. He defends an orbital conception of morally relevant harm, according to which harms that fall within the ‘orbit’ of a given harm are relevant to it, while all other harms are not. The possibility of preventing a harm provides both a first-order reason to prevent that harm, and a second-order reason not to consider preventing irrelevant harms. This understanding of a morally relevant harm avoids two objections to such a concept recently raised by Alastair Norcross: identifying a point along a continuous scale of harms at which the divide between relevant and irrelevant harms occurs, and the entailment that the mere possibility of preventing harm that one is morally forbidden from preventing can determine which of two other actions morality requires.
The Right Kind of Solution to the Wrong Kind of Reason Problem
Authors: LANG GERALD
Published: November 2008

Recent discussion of Scanlon's ‘buck-passing’ account of value, which analyses the value of X in terms of agents' reasons for having certain pro-attitudes or contra-attitudes towards X, has generated the ‘wrong kind of reason’ problem (WKR problem): this is the problem, for the buck-passing view, of being able to acknowledge that there may be good reasons for attributing final value to X that have nothing to do with the final value that X actually possesses. I briefly review some of the existing solutions offered to the WKR problem, including those by Philip Stratton-Lake and Jonas Olson, and offer a new, better one, which accommodates all the relevant cases presented in the literature.
Mutual Smiling Episodes and Therapeutic Alliance in a Therapist-Couple Discussion Task
Authors: Darwiche Joëlle , de Roten Yves , Stern Daniel J. , von Roten Fabienne Crettaz , Corboz-Warnery Antoinette , Fivaz-Depeursinge Elisabeth
Published: November 2008

We observed mutual smiling episodes (MSEs) during therapist-couple triadic interaction as a key element of affective exchanges that serve to regulate the therapeutic relationship. Based on a functional perspective, we developed a new rating scale, the MSE Coding System (MSE-CS) that allows us to distinguish between four different MSEs, which correspond to four social functions: supporting mutual binding, sharing miseries, repairing, and confronting. MSEs were analyzed in a sample of eight therapist-couple triads. Therapeutic alliance and marital adjustment were also measured. The instrument (MSE-CS) demonstrated satisfactory inter-rater reliability, and initial indications of validity are promising. Results showed that number of MSEs was positively correlated with triadic therapeutic alliance. Types of MSEs were also distributed differently depending on the level of triadic therapeutic alliance.
Quantile trends in Baltic sea level
Authors: Barbosa Susana M.
Published: November 2008

Quantile regression is applied for characterizing long‐term sea‐level variability in the Baltic Sea from long tide gauge records. The approach allows to quantify not only variability in the mean but also in extreme heights and thus provides a more complete description of regional sea‐level variability. In the Baltic, slopes in minima are similar to the classical mean‐based ordinary least squares slope, but maxima exhibit larger trends, particularly at the northernmost stations, in the Gulf of Bothnia, likely associated with changes in north Atlantic atmospheric circulation and particularly regional wind patterns.
Measurements of SO2 profiles in volcanic plumes from the NASA Tropospheric Emission Spectrometer (TES)
Authors: Clerbaux C. , Coheur P.‐F. , Clarisse L. , Hadji‐Lazaro J. , Hurtmans D. , Turquety S. , Bowman K. , Worden H. , Carn S. A.
Published: November 2008

Satellite measurements are now recognized as a key element for the early detection and characterization of volcanic eruptions, in particular in the context of aircraft routing. A common tracer of volcanic plumes is sulfur dioxide (SO2), which so far has been measured by ultraviolet‐visible (UV‐vis) instruments and multispectral infrared (IR) sounders. Here we report the first SO2 vertical profile retrieved from high spectral resolution thermal infrared nadir radiance spectra and we provide information on both the quantity of gas emitted and its altitude. From the radiance spectra provided by the Tropospheric Emission Spectrometer (TES) aboard the NASA AURA satellite, and owing to the ∼0.1 cm−1 (apodized) spectral resolution, elevated levels of SO2 were measured following volcanic eruptions occurring in 2005 (Manam, Sierra Negra) and 2006 (Rabaul, Nyamuragira). Column values are found to be in good agreement with the data provided by Ozone Mapping Instrument (OMI), a UV‐vis instrument also onboard the AURA satellite.
No interconnection of ferro‐periclase in post‐spinel phase inferred from conductivity measurement
Authors: Yoshino Takashi , Yamazaki Daisuke , Ito Eiji , Katsura Tomoo
Published: November 2008

Electrical conductivities of post‐spinel, which are thought to be a dominant assembly in the lower mantle, were investigated at the conditions of the uppermost lower mantle (25 GPa and temperatures ranging from 300 to 2000K) in a Kawai‐type multi‐anvil apparatus. Post‐spinel phases with a bulk composition of ((Mg,Fe)2SiO4: XFe = 0.09) were measured to constrain the bulk conductivity of the lower mantle. To investigate interconnectivity of ferro‐periclase in silicate perovskite matrix, a single phase composed of magnesium silicate perovskite ((Mg,Fe)SiO3: XFe = 0.1) and ferro‐periclase ((Mg,Fe)O: XFe = 0.13) were also measured. The conductivity values of the silicate perovskite are distinctly lower than those for the coexisting ferro‐pericalse. Both absolute values and change in activation enthalpy for the conductivity of the post‐spinel phases are similar to those for the silicate perovskite. These observations suggest that ferro‐periclase in post‐spinel are isolated in silicate perovskite matrix.
Elastoviscoplastic micromechanical modeling of the transient creep of ice
Authors: Castelnau O. , Duval P. , Montagnat M. , Brenner R.
Published: November 2008

A salient feature of the rheology of isotropic polycrystalline ices is the decrease of the strain rate by more than 2 orders of magnitude during transient creep tests to reach a secondary creep regime at a strain which is systematically of ∼1%. We use a recent (so‐called “affine”) version of the self‐consistent mean‐field theory to model the elastoviscoplastic behavior of ice. The model aims at bridging scales between the rheology of single grain and the one of polycrystals by evaluating the intergranular interactions. It takes into account the long‐term memory effects, which manifests itself by the fact that local stress and strain rate in grains depend on the whole mechanical history of the polycrystal. It is shown that the strong hardening amplitude during the transient creep is entirely explained by the stress redistribution within the specimen, from an almost uniform stress distribution upon instantaneous loading (purely elastic response) to strong interphase and intraphase heterogeneities in the stationary regime (purely viscoplastic response). The experimental hardening kinetic is much too slow to be explained by the same process; it is attributed to the hardening of hard glide slip systems (prismatic slip) in the transient regime. Moreover, the model very well reproduces the permanent creep rate of several highly anisotropic specimens of the Greenland Ice Core Project ice core (pronounced crystallographic textures), when accounting for a single‐grain rheology that well matches the experimental one. Our results are consistent with recent findings concerning dislocation dynamics in ice.
Simulation of local air‐sea interaction in the great warm pool and its influence on Asian monsoon
Authors: Duan Anmin , Sui Chunghsiung , Wu Guoxiong
Published: November 2008

An ocean mixed layer model was coupled to an atmospheric general circulation model (AGCM) with the aim to investigate the effect of local air‐sea interaction on Asian summer monsoon (ASM). When local air‐sea interaction was allowed in the great warm pool [GWP, i.e., oceans with annual mean sea surface temperature (SST) above 28°C across Indian Ocean and the western Pacific], the simulated ASM climatology presents a substantial improvement in both the precipitation distribution and monsoon onset timing compared to the AGCM control run. To illustrate the main physical processes responsible for such a change, another AGCM sensitivity experiment was conducted, in which SST within the GWP was derived from output of the coupled run whereas SST outside the GWP are identical to the AGCM control run. Intercomparison results indicate that air‐sea interaction modulates SST efficiently via wind‐evaporation and cloud‐radiation processes for most parts of the GWP, which in turn influences atmospheric circulation and precipitation pattern. In the Bay of Bengal, for example, SST reaches its annual peak before the monsoon onset and increases the atmospheric instability and moisture convergence above it, providing a favorable background for the development of deep convection. After the monsoon onset, however, increased surface wind speed and deceased incoming solar radiation flux lead to the colder in situ SST, lower humidity, and weaker convection. Hence properly representation of local air‐sea interaction is crucial in mimicking and predicting the ASM in the coupled model.
Spatial variability of CO2efflux in a drained cropped peatland south of Venice, Italy
Authors: Camporese M. , Putti M. , Salandin P. , Teatini P.
Published: November 2008

A field experimental study has been performed in a drained cropped peatland located in the Zennare Basin (south of the Venice Lagoon, Italy), to measure land subsidence due to peat oxidation and to address the primary relationships between the hydrological regime, the soil mass loss (in form of CO2efflux to the atmosphere), and the settlement rate. The latter, of the order of 0.01–0.02 m/a, has been proved to be related to soil CO2efflux due to organic matter oxidation. A series of CO2emission measurement campaigns has been performed between the years 2003 and 2005. The non‐steady‐state chamber method was employed to assess the efflux spatial variability and detect its relationship with the main hydrological parameters controlling the oxidation reaction, i.e., soil temperature, soil moisture, and organic matter content. The measurements, carried out in two sites located 1.5 km apart, point out a great variability of the CO2emissions both in space and time. While the time‐dependent behavior can be explained by the seasonal fluctuation of soil temperature, spatial variability shows a weak correlation with the variation of environmental variables. Statistical data analyses show that CO2efflux can be considered lognormally distributed and that the process is stationary within each site but not in the whole basin, though the properties of the outcropping peat layer and the soil surface seem apparently uniform. A geostatistical analysis reveals two different spatial correlation structures, with scales of spatial dependence of ≈30 m and ≈180 m. Finally, the collected data show that invasive agricultural practices such as deep plowing, tilling, and harrowing, largely used in the Zennare Basin, induce significant disturbances that are not easily recognizable during the flux surveys and that casually affect the temporal and spatial variability of the oxidation process.
Structure of gold atoms on stoichiometric and defective ceria surfaces
Authors: Zhang Changjun , Michaelides Angelos , King David A. , Jenkins Stephen J.
Published: November 2008

Within the framework of the GGA+U implementation of density functional theory, we investigate atomistic and electronic structures of Au adsorbed on the stoichiometric and the defective CeO2{111} surfaces, in the latter of which either O or Ce vacancies are presented. We show that on the stoichiometric surface, the most stable adsorption site of Au is not on the top of the outermost O atoms, as previously suggested, but on a bridgelike site in which the Au directly binds to two O atoms. We suggest that on both sites, the original empty Ce 4f states near the Fermi level facilitate the oxidation of the Au; the preference of the Au for being on the bridgelike site is due to the larger O 2p-d(Au) mixing, accompanied by more significant electron redistributions. On the reduced surface with O vacancies, the most stable adsorption site of Au is near the vacancy position. Unlike that on the stoichiometric surface, strong ionic bonding character exists between Au and Ce, as the former becomes Auδ− due to the occupation of the 6s(Au) orbitals. Upon substitution for one of the Ce atoms in the lattice, the Au possesses a much stronger positive charge than that in other cases. We find that although Au is strongly bonded when it is at the Ce vacancy site, the overall binding (i.e., with the Ce vacancy formation energy being taken into account) is weaker than that for Au adsorbed at the stoichiometric surface.
Optical properties of silicon nanocrystals in silica: Results from spectral filtering effect, m-line technique, and x-ray photoelectron spectroscopy
Authors: Khriachtchev Leonid , Nikitin Timur , Oton Claudio J. , Velagapudi Rama , Sainio Jani , Lahtinen Jouko , Novikov Sergei
Published: November 2008

The optical properties of silica layers containing silicon nanocrystals are analyzed in terms of spectral filtering in absorbing planar waveguides (cutoff spectra), m-line measurements, and x-ray photoelectron spectroscopy (XPS). The effects of optical dispersion, approximation of weak guiding, and depth dependence of refractive index in a planar waveguide are studied. We compare the measured optical properties of silicon-rich silicon oxide samples with the values estimated by the Bruggeman theory using the XPS structural components. A good agreement between the measured and calculated refractive indices is found. The results for absorption suggest high transparency of the nanoscale-suboxide component in contrast to the corresponding bulk material. The Raman intensity of silicon nanocrystals is proportional to the XPS amount of bulk silicon. The extinction coefficient extracted for the Si component is between the values for crystalline and amorphous silicon. Annealing at higher temperatures decreases the Si component extinction coefficient, which is interpreted as a decrease in the amorphous Si fraction. The XPS method surprisingly suggests a large proportion of silicon suboxide even after annealing at 1200 °C.
The CCSD(T) complete basis set limit for Ne revisited
Authors: Barnes Ericka C. , Petersson George A. , Feller David , Peterson Kirk A.
Published: November 2008

Recent estimates of the CCSD(T)(FC) limit for the neon atom (−128.8690±0.001 and −128.8687±0.0005 hartree) are refined. Re-examination of the basis set convergence of the separate self-consistent field, MP2-αβ, MP2-αα, CCSD–MP2, and (T) components of the valence CCSD(T) energy gives a complete basis set limit of −128.869 236±0.000 02 hartree. This can now be used as an improved benchmark to calibrate more approximate calculations.
The Alzheimer β-amyloid (Aβ1–39) dimer in an implicit solvent
Authors: Anand Priya , Nandel Fateh S. , Hansmann Ulrich H. E.
Published: November 2008

Oligomers of Aβ peptides are suspected as the underlying cause of Alzheimer disease. Knowledge of their structural properties could therefore lead to a deeper understanding of the mechanism behind the outbreak of this disease. As a step in this direction we have studied Aβ dimers by all-atom molecular dynamics simulations. Equilibrated structures at 300 K were clustered into different families with similar structural features. The dominant cluster has parallel N-terminals and a well defined segment Leu17-Ala21 that are stabilized by salt bridges between Lys28 of one chain and either Glu22 or Asp23 of the other chain. The formation of these salt bridges may be the limiting step in oligomerization and fibrillogenesis.
Molecular second harmonic generation induced at a metallic tip
Authors: Berline I. , Fiorini-Debuisschert C. , Royal C. , Douillard L. , Charra F.
Published: November 2008

We report the measurement of efficient second harmonic generation at a metallic tip immersed in a molecular solution of highly nonlinear molecules. The dependence of the signal either with the tip-to-substrate applied voltage or with the tip-to-substrate distance is studied. We show that the signal originates from the orientation of a limited number of molecules following local centrosymmetry breaking under the tip. The results are discussed within the context of scanning probe microscopy.
Characterizing the global dispersion of carbon nanotubes in ceramic matrix nanocomposites
Authors: Koszor Orsolya , Tapasztó Levente , Markó Márton , Balázsi Csaba
Published: November 2008

The dispersion of single-walled carbon nanotubes in silicon nitride ceramic matrices has been investigated by small angle neutron scattering experiments. In contrast to electron microscopy investigations of fracture surfaces, neutron scattering measurements provide information on the bulk dispersion of nanotubes within the matrix. The scattering intensities reveal a decay exponent characteristic to surface fractals, which indicates that the predominant part of nanotubes can be found in loose networks surrounding the grains of the polycrystalline matrix.
Controlling multidomain states to enable sub-10-nm magnetic force microscopy
Authors: Amos Nissim , Ikkawi Rabee , Haddon Robert , Litvinov Dmitri , Khizroev Sakhrat
Published: November 2008

The letter reports experimental data to demonstrate magnetic force microscopy (MFM) with sub-10-nm resolution under ambient conditions. To achieve this record high resolution, multidomain states in a nanomagnetic probe were controlled. Two demagnetized (multidomain) FePt (45/55) films sputtered on a silicon probe and separated by an 8 nm thick MgO layer were further annealed at temperature of 650 °C to trigger the high-anisotropy L10 phase. A field of above 2 T was applied to drive the probes into a saturated “single-domain” state. The multidomain probes were equivalently compared with state-of-the-art conventional MFM probes via comparative imaging of benchmark magnetic recording disks.
Network analysis identifies weak and strong links in a metapopulation system
Authors: Rozenfeld Alejandro F. , Arnaud-Haond Sophie , Hernández-García Emilio , Eguíluz Víctor M. , Serrão Ester A. , Duarte Carlos M.
Published: November 2008

The identification of key populations shaping the structure and connectivity of metapopulation systems is a major challenge in population ecology. The use of molecular markers in the theoretical framework of population genetics has allowed great advances in this field, but the prime question of quantifying the role of each population in the system remains unresolved. Furthermore, the use and interpretation of classical methods are still bounded by the need for a priori information and underlying assumptions that are seldom respected in natural systems. Network theory was applied to map the genetic structure in a metapopulation system by using microsatellite data from populations of a threatened seagrass,
Posidonia oceanica
, across its whole geographical range. The network approach, free from a priori assumptions and from the usual underlying hypotheses required for the interpretation of classical analyses, allows both the straightforward characterization of hierarchical population structure and the detection of populations acting as hubs critical for relaying gene flow or sustaining the metapopulation system. This development opens perspectives in ecology and evolution in general, particularly in areas such as conservation biology and epidemiology, where targeting specific populations is crucial.
Cell packing influences planar cell polarity signaling
Authors: Ma Dali , Amonlirdviman Keith , Raffard Robin L. , Abate Alessandro , Tomlin Claire J. , Axelrod Jeffrey D.
Published: November 2008

Some epithelial cells display asymmetry along an axis orthogonal to the apical-basal axis, referred to as planar cell polarity (PCP). A Frizzled-mediated feedback loop coordinates PCP between neighboring cells, and the cadherin Fat transduces a global directional cue that orients PCP with respect to the tissue axes. The feedback loop can propagate polarity across clones of cells that lack the global directional signal, although this polarity propagation is error prone. Here, we show that, in the
Drosophila
wing, a combination of cell geometry and nonautonomous signaling at clone boundaries determines the correct or incorrect polarity propagation in clones that lack Fat mediated global directional information. Pattern elements, such as veins, and sporadic occurrences of irregular geometry are obstacles to polarity propagation. Hence, in the wild type, broad distribution of the global directional cue combines with a local feedback mechanism to overcome irregularities in cell packing geometry during PCP signaling.
Diabetes and psychological co‐morbidity in children with a family history of early‐onset type 2 diabetes
Authors: Irving Rachael R. , Mills James L. , Choo‐Kang Eric G. , McLaughlin Wayne , Wright‐Pascoe Rosemarie , Morrison Errol Y. , Brown Paul
Published: November 2008

The present study was conducted to evaluate for depressive symptoms and undiagnosed diabetes in children with familial history of early‐onset type 2 diabetes. Studies have shown that diabetes doubles the risk for depression and that the duration of diabetes is related to the severity of the depression. Individuals with depression are also said to be at greater risk for developing diabetes. In many cases diabetes is detected whilst screening for depression. Fifty‐three children aged between 6 and 17 years were screened for diabetes and assessed for depressive symptoms using the Children Depression Rating Scale, revised version (CDRS‐R). Thirty‐six (68.0 %) of the children with a family history of early‐onset type 2 diabetes had CDRS‐R scores consistent with likely or very likely major depressive disorders. Depressive symptoms score was predicted best by the number of generations of diabetes in the family, with an associated r = .65 and adjusted R2 = .41. As the generations of diabetes increased, the more likely it was for a child to have diabetes (r = .38, p = .005). Four (7.5%) of the children were diagnosed with diabetes. The findings suggest that depressive symptoms are common in children with a family history of early onset type 2 diabetes and may co‐exist with diabetes. The independent variable that reliably predicted the child depressive symptoms score was the number of generations of diabetes in the family.
Pathways to State Failure
Authors: Goldstone Jack A.
Published: November 2008

Attempts to forecast or remedy state failure would benefit from a clearer view of the multiple pathways that can lead states to fail. This paper delineates five pathways: escalating ethnic conflicts, state predation, regional guerrilla rebellion, democratic collapse, and succession/reform crises in authoritarian states. Each of these five pathways involves changes in the legitimacy and effectiveness of regimes; state failures follow upon the loss of both legitimacy and effectiveness. Examples are provided and guidelines are offered for efforts to avert failure in fragile states.
Bad Neighbors: Failed States and Their Consequences
Authors: Iqbal Zaryab , Starr Harvey
Published: November 2008

State failure reflects the collapse of a sovereign state, and has been hypothesized to destabilize an entire region. We assess the negative effects of state collapse, focusing particularly on the spatial diffusion of these consequences. We argue that the instability, unrest, and civil war that increase the risk for state collapse are not limited to the failed/collapsed state; states neighboring—or located within close distance of—a failed state are also likely to experience subsequently higher levels of political instability, unrest, civil war, and interstate conflict. We also evaluate the likelihood of state failure itself diffusing to other states. Specifically, we test the proposition that state failure causes political turmoil in nearby states to a greater extent than in distant countries. We do so by including a distance-weighted measure of state failure and by evaluating the effect of collapse in contiguous states. We conclude that state failure/collapse itself is not contagious, but some of its most negative consequences do indeed diffuse to other states.
What are the Preconditions for Turnarounds in Failing States?
Authors: Chauvet Lisa , Collier Paul
Published: November 2008

This paper analyzes the preconditions for sustained policy turnarounds in failing states. Our dependent variable is the probability of the commencement of a turnaround that eventually becomes both sustained and substantial. We focus upon the explanatory variables of resource rents, education, and aid, distinguishing between finance and technical assistance. Overall, we find that these variables have significant and large effects on the duration of state failure. Appropriate donor intervention can radically shorten state failure, whereas additional finance, whether from aid or resource rents, has the opposite effect.
State Fragility and Implications for Aid Allocation: An Empirical Analysis
Authors: Carment David , Samy Yiagadeesen , Prest Stewart
Published: November 2008

In recent years, state fragility has gained importance as a result of the perceived links between poverty, conflict, and global terrorism. In this paper, we examine the relationship between state fragility and aid by evaluating the literature and research programs currently extant. We bring conceptual clarity to the issue by developing and testing an alternative theoretical framework using CIFP's fragility index (articulated around the concepts of authority, legitimacy, and capacity [ALC]) and by using data collected for the period 1999—2005 to identify the empirical determinants of fragility. We then examine the effects of state fragility on aid allocation, using the ALC framework as defined. Our results indicate that aid allocation is directed toward states on the basis of their capacity and authority scores and not on the basis of their legitimacy scores. Finally, we assess the theoretical and policy implications of these findings and specify directions for future research.
Molecular mechanism for generation of antibody memory
Authors: Shivarov Velizar , Shinkura Reiko , Doi Tomomitsu , Begum Nasim A , Nagaoka Hitoshi , Okazaki Il-Mi , Ito Satomi , Nonaka Taichiro , Kinoshita Kazuo , Honjo Tasuku
Published: November 2008

Activation-induced cytidine deaminase (AID) is the essential enzyme inducing the DNA cleavage required for both somatic hypermutation and class switch recombination (CSR) of the immunoglobulin gene. We originally proposed the RNA-editing model for the mechanism of DNA cleavage by AID. We obtained evidence that fulfils three requirements for CSR by this model, namely (i) AID shuttling between nucleus and cytoplasm, (ii) de novo protein synthesis for CSR, and (iii) AID–RNA complex formation. The alternative hypothesis, designated as the DNA-deamination model, assumes that the
in vitro
DNA deamination activity of AID is representative of its physiological function
in vivo
. Furthermore, the resulting dU was removed by uracil DNA glycosylase (UNG) to generate a basic site, followed by phosphodiester bond cleavage by AP endonuclease. We critically examined each of these provisional steps. We identified a cluster of mutants (H48A, L49A, R50A and N51A) that had particularly higher CSR activities than expected from their DNA deamination activities. The most striking was the N51A mutant that had no ability to deaminate DNA
in vitro
but retained approximately 50 per cent of the wild-type level of CSR activity. We also provide further evidence that UNG plays a non-canonical role in CSR, namely in the repair step of the DNA breaks. Taking these results together, we favour the RNA-editing model for the function of AID in CSR.