bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced light emission from an organic photonic crystal with a nanocavity
Authors: Kitamura M. , Iwamoto S. , Arakawa Y.
Published: November 2005

An organic photonic crystal (PC) with a nanocavity has been fabricated on a SiO2 membrane with air holes. The emission peak caused by the resonant mode of the nanocavity was clearly observed from the nanocavity area of the PC. The emission peak corresponded to degenerated dipole modes from comparison between measured and calculated results. Modification of a nanocavity caused the peak splitting of dipole modes and the appearance of a peak corresponding to a hexapole mode. The emission peak with a quality factor of about 1000 was obtained from a PC with a modified nanocavity.
Subpicosecond luminescence spectroscopy of exciton localization in InxGa1−xN films
Authors: Kanemitsu Yoshihiko , Tomita Koichi , Inouye Hideyuki
Published: November 2005

We have studied the exciton localization dynamics in InxGa1−xN epitaxial films with different In compositions (x=0.02, 0.05, and 0.09) by means of optical Kerr-gate time-resolved photoluminescence (PL) spectral measurements. By changing excitation wavelength of 150fs laser pulses, InxGa1−xN films are resonantly excited around their exciton energies at 6K. Under the resonant excitation, the PL dynamics is sensitive to the In composition of the sample and the excitation laser intensity. In the low In composition samples, the formation time of radiative excitons at localized states is 5–10ps. In the high In composition samples, the gradual redshift of the PL peak energy is observed within several tens of picoseconds. The radiative recombination processes of excitons are discussed.
Time-resolved pulsed-plasma characterization using broadband terahertz pulses correlated with fluorescence imaging
Authors: Kolner B. H. , Conklin P. M. , Buckles R. A. , Fontaine N. K. , Scott R. P.
Published: November 2005

Near-monocycle terahertz (THz)-bandwidth electromagnetic pulses have been used to probe pulsed-discharge argon plasmas at various pressures from 10to50Torr. Time-resolved electric field measurements were made of the THz pulse with and without plasma allowing a full characterization of the real and imaginary parts of the plasma index of refraction. Electron densities ne⩾1013cm−3 and collision rates γp⩾1011s−1 were deduced by applying a simple Lorentz model to the measured time-domain pulse with no plasma and comparing it to the measured pulse with the plasma present. Minimizing the rms error between these in the two-dimensional parameter space (ne,γp) fixed the values for each point in time of the plasma evolution. Optical fluorescence imaged transverse to the THz beam path was used to estimate the density profile used in the propagation model.
Divergences in quantum electrodynamics on a graph
Authors: Kan Nahomi , Shiraishi Kiyoshi
Published: November 2005

We consider a model of quantum electrodynamics (QED) on a graph as the generalization of dimensional deconstruction with the Abelian symmetry. Arbitrary structures of the theory space correspond to the graphs consisting of vertices and edges. The mass spectrum of the model is expressed in terms of eigenvalues of the Laplacian for the graph. We also find that physical massless scalar modes are associated with the fundamental tie set matrix on the graph. We further investigate the one-loop divergences in the model by use of the background field method.
Nested stochastic simulation algorithm for chemical kinetic systems with disparate rates
Authors: E Weinan , Liu Di , Vanden-Eijnden Eric
Published: November 2005

An efficient simulation algorithm for chemical kinetic systems with disparate rates is proposed. This new algorithm is quite general, and it amounts to a simple and seamless modification of the classical stochastic simulation algorithm (SSA), also known as the Gillespie [J. Comput. Phys. 22, 403 (1976); J. Phys. Chem. 81, 2340 (1977)] algorithm. The basic idea is to use an outer SSA to simulate the slow processes with rates computed from an inner SSA which simulates the fast reactions. Averaging theorems for Markov processes can be used to identify the fast and slow variables in the system as well as the effective dynamics over the slow time scale, even though the algorithm itself does not rely on such information. This nested SSA can be easily generalized to systems with more than two separated time scales. Convergence and efficiency of the algorithm are discussed using the established error estimates and illustrated through examples.
Solvent phase behavior and the interaction of uniform and patterned solutes
Authors: Overduin S. D. , Patey G. N.
Published: November 2005

Isotropic and anisotropic hypernetted-chain (HNC) integral equation theories are used to obtain the interaction of solutes both near and far from the solvent liquid-vapor coexistence. Spherically symmetrical and chemically patterned (patched) solutes are considered, and the influences of particle and patch sizes are investigated. Solvophilic and solvophobic solutes (or patches) are examined. Near coexistence, in the solvophobic case dryinglike behavior occurs for solutes (patches) of sufficient size. This gives rise to relatively long ranged attractive forces that are strongly orientation dependent for the patched solute particles. We also report grand canonical Monte Carlo results for a pair of spherically symmetric solutes. This demonstrates that the anisotropic HNC theory gives qualitatively correct solvent structure in the vicinity of the solutes. Comparison with previous simulations also shows that the solute-solute potentials of mean force given by the anisotropic theory are more accurate (particularly at small separations) than those obtained using the isotropic method.
On the Cauchy problem for the integrable system of Lie minimal surfaces
Authors: Musso E. , Nicolodi L.
Published: November 2005

In this paper we apply the Cartan-Kähler theory of exterior differential systems to solve the Cauchy problem for the integrable system of Lie minimal surfaces and discuss the underlying geometry. One purpose for this work is to show how methods and language from the theory of exterior differential systems may prove to be useful in the study of real analytic initial value problems, especially for gaining insight into the geometric aspects of the initial conditions and the solutions.
Quantum state-to-state rate constants for the rotationally inelastic collision of CH(BΣ−2, ν=, N→N′) with Ar
Authors: Chao Sheng Der , Lin Sheng Hsien , Alexander Millard H.
Published: November 2005

We have calculated the state-to-state integral cross sections and rate constants for the rotationally inelastic collision of CH(BΣ−2, ν=0, N→N′) with Ar using the quantum coupled-state and close-coupling methods on an ab initio potential-energy surface constructed by Alexander et al. [J. Chem. Phys. 101, 4547 (1994)]. Overall the calculated rate constants are in good agreements with the three available experimental results. The rate constants are comparable to the usual gas kinetic and decrease with increasing N and ΔN. For the multiquantum transition cases, the theory underestimates the experiment. We discuss some possible causes to the discrepancies among the theory and the experiments.
Preliminary analysis of C and H in a “Sangiran” fossil using laser-induced plasma at reduced pressure
Authors: Suliyanti Maria Margaretha , Sardy Sar , Kusnowo Anung , Pardede Marincan , Hedwig Rinda , Kurniawan Koo Hendrik , Lie Tjung Jie , Kurniawan Davy Putra , Kagawa Kiichiro
Published: November 2005

A Nd:YAG laser (1064nm, 120mJ, and 8ns) was focused on various types of fossil samples, including fossilized buffalo horns (around 400 000 and 1×106yr old, respectively) found in Sangiran, Indonesia. Such fossils represent an important starting point for tracing man’s origin and evolution during the Pleistocene era. Carbon emission was found to decrease significantly with the degree of fossilization and no carbon emission was found in a horn fossil dated at 1×106yr. Some molecular band spectra were also found in all the fossils examined in this study. It was assumed that by combining information on carbon emission, hydrogen emission, and molecular band spectra that the degree of fossilization might be quantitatively calculated. Further results showed that silicon emission is not detected in old fossils, but it is present as a major constituent. This is probably due to the fact that silicon is strongly bound to other elements in old fossils and is ablated in the form of clusters. In order to prove the above hypothesis, a thin film of an old fossil was deposited on a silver plate substrate by means of a laser ablation technique. The resulting film was then irradiated and atomic emission lines of silicon were clearly detected. A comparative study of the low-pressure plasma introduced in this study was conducted using the well-known laser-induced breakdown spectroscopy technique and the results confirmed that operating conditions at atmospheric pressure are unfavorable for a fossil analysis.
Touch sensor for micromanipulation with pipette using lead-free (K,Na)(Nb,Ta)O3 piezoelectric ceramics
Authors: Motoo Kohei , Arai Fumihito , Fukuda Toshio , Matsubara Masato , Kikuta Koichi , Yamaguchi Toshiaki , Hirano Shin-ichi
Published: November 2005

In the field of applied microbiology, a touch sensor for micromanipulation with a pipette is needed. Therefore, we previously developed a touch sensor using Pb(Zr,Ti)O3 (PZT). The piezoelectric material is used for vibration of the pipette and for measurement of the change in mechanical impedance caused by the pipette tip contacting the object being measured. However, the lead included in PZT can cause environmental problems. Therefore, in the present work, we developed a touch sensor using lead-free (K,Na)(Nb,Ta)O3 (KNNT) ceramics, which are strong candidates for lead-free piezoelectric ceramics. In this study, characteristics of a touch sensor utilizing piezoelectric vibration were theoretically derived. The results show that the piezoelectric constant d31 is very important: the higher the mode of vibration, the smaller the tip amplitude; the lower the mode of vibration, the higher the sensitivity. Also, the higher the elasticity or viscosity of the object in contact with the sensor, the higher the sensitivity. These theoretical results qualitatively correspond to the experimental results. The piezoelectric constant d31 of KNNT ceramics was measured, and its value was found to be greater than or equal to 100pm∕V. KNNT ceramics were applied to the touch sensor and its utility was confirmed.
Field-enhanced ionization of deep-level centers as a triggering mechanism for superfast impact ionization fronts in Si structures
Authors: Rodin Pavel , Rodina Anna , Grekhov Igor
Published: November 2005

We investigate the origin of free carriers that initiate impact ionization in depleted high-voltage p-n junctions under dynamic breakdown conditions and deterministically trigger superfast ionization fronts that propagate several times faster than the saturated drift velocity. We argue that in Si structures triggering occurs due to the field-enhanced ionization of process-induced deep-level centers identified as sulfur impurities. This impurity is a double-level electron trap with low recombination activity. It is present in high-voltage Si structures due to the side effect of widely used fabrication technology. We calculate the field and temperature dependences of the ionization probability for the upper midgap level (0.28eV) and midgap level (0.54eV) in electric fields up to 5×105V∕cm as well as the occupation of these levels at different temperatures. The emission of free electrons is sufficient to trigger the ionization front from zero temperature to ∼400K, in agreement with experiments. At room temperature the front is triggered due to the phonon-assisted tunneling from the midgap level with an ionization energy of 0.54eV. For temperatures below 200K all double-level centers are in the ground state and the front is triggered due to the direct tunneling from the upper midgap level with an ionization energy of 0.28eV.
Power balance at cathode in glow discharges
Authors: Suraj K. S. , Mukherjee S.
Published: November 2005

When an electrode is biased negatively (∼ few hundred volts) with respect to a metallic chamber, maintained at a subatmospheric pressure (∼ few millibars), glow discharge plasma is formed around the electrode (cathode). The plasma supplies ions and other species to the cathode, along with other events at the cathode, and its temperature also rises. From the measurement of temporal temperature profile, in the pressure range of 0.5–5mbars, the thermal influx at the cathode has been determined. Various modes of power input to the cathode are estimated from the discharge parameters. The contribution of ions and neutrals to the total input power is obtained theoretically from respective velocity distributions at the cathode considering charge exchange as the dominant collision mechanism inside the sheath region. The comparison of experimental and theoretical results suggests that in the pressure range being considered, which is typical of glow discharges, the major contribution to the energy input at the cathode comes from energetic neutrals generated by the charge-exchange collision inside the collisional ion sheath.
Probe diagnosis of electron temperature and electron energy distribution in low-pressure dielectric barrier discharge
Authors: Ling Yi-Ming
Published: November 2005

The double-probe method is used to diagnose electron temperature and electron energy distribution in low-pressure dielectric barrier discharge (DBD). In this paper, the principle and the setup of diagnosis are described and the experimental results are discussed briefly. The results demonstrate that its electron temperature decreases with the increasing gas-filled pressure and is higher than that in dc discharge under the same discharge condition. It is also evident from experiment that its electron energy distribution is evidently deviated from Maxwellian. There are electron groups of high energy and low energy in the DBD, and the electron group of high energy decreases gradually with the increasing pressure.
Direct comparisons of compressible magnetohydrodynamics and reduced magnetohydrodynamics turbulence
Authors: Dmitruk Pablo , Matthaeus William H. , Oughton Sean
Published: November 2005

Direct numerical simulations of low Mach number compressible three-dimensional magnetohydrodynamic (CMHD3D) turbulence in the presence of a strong mean magnetic field are compared with simulations of reduced magnetohydrodynamics (RMHD). Periodic boundary conditions in the three spatial coordinates are considered. Different sets of initial conditions are chosen to explore the applicability of RMHD and to study how close the solution remains to the full compressible MHD solution as both freely evolve in time. In a first set, the initial state is prepared to satisfy the conditions assumed in the derivation of RMHD, namely, a strong mean magnetic field and plane-polarized fluctuations, varying weakly along the mean magnetic field. In those circumstances, simulations show that RMHD and CMHD3D evolve almost indistinguishably from one another. When some of the conditions are relaxed the agreement worsens but RMHD remains fairly close to CMHD3D, especially when the mean magnetic field is large enough. Moreover, the well-known spectral anisotropy effect promotes the dynamical attainment of the conditions for RMHD applicability. Global quantities (mean energies, mean-square current, and vorticity) and energy spectra from the two solutions are compared and point-to-point separation estimations are computed. The specific results shown here give support to the use of RMHD as a valid approximation of compressible MHD with a mean magnetic field under certain but quite practical conditions.
Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules
Authors: Sanz J. , Garnier J. , Cherfils C. , Canaud B. , Masse L. , Temporal M.
Published: November 2005

In the context of the French Laser-Mégajoule fusion-research program, the hydrodynamic stability of the baseline direct-drive target is investigated at the hot spot surface during the deceleration phase by means of modeling and simulations. Using the convergence of the flow towards a self-similar solution, a closed system of ordinary differential equations is derived for the main hydrodynamic variables. An exact linear stability analysis is performed to compute the Rayleigh-Taylor growths. All theoretical predictions are compared to one-dimensional and two-dimensional single-mode detailed numerical results.
Overpoling resistance of [011]-poled Pb(Mg1∕3Nb2∕3)O3–PbTiO3 single crystals
Authors: Shanthi M. , Chia S. M. , Lim L. C.
Published: November 2005

[011]-poled flux-grown Pb(Mg1∕3Nb2∕3)O3–PbTiO3 (PMN–32%PT) single crystals are susceptible to overpoling at 0.4kV∕mm and higher fields, leading to degraded properties. This has been linked to the presence of an appreciable amount of the orthorhombic phase induced by the high poling fields. In contrast, flux-grown PMN–30%PT and PMN–31%PT single crystals show no signs of overpoling up to 2.0kV∕mm, both of which remain predominantly rhombohedral with a small amount of induced orthorhombic phase. Among the three compositions examined, flux-grown PMN–30%PT single crystal gives the best [011]-poled properties, with KT=5500–6000, d31=2100–2600pC∕N, and k31=0.90–0.94. The present work further shows that, for a given crystal composition, flux-grown PMN–PT single crystals exhibit superior overpoling resistance to their melt-grown counterparts.
Steady rotating flows over a ridge
Authors: Esler J. G. , Rump O. J. , Johnson E. R.
Published: November 2005

A model describing rotating single-layer flows over a parabolic ridge is investigated. A method of constructing steady solutions is introduced, and is used to extend previous results and determine exact regime diagrams describing the qualitative nature of the solution. Analytic expressions for the boundaries between transcritical flow and supercritical and subcritical flows are given as a function of obstacle height, Froude number of the upstream flow, and the flow inverse Burger number (a nondimensional number proportional to the square of the rotation rate). For fixed obstacle height, the nature of the supercritical transition is found to change as the rotation rate increases, with a hysteresis region like that in nonrotating flow being present only at lower rotation rates. At higher rotation rates, solutions with stationary jumps over the obstacle become stable, and abrupt transitions between supercritical and transcritical flow no longer occur. An exact analytic expression is also found for transcritical flow over the obstacle, which is closely related to the solutions for nonlinear inertia-gravity waves of limiting amplitude found by Shrira. For sufficiently high ridges in initially supercritical flow, a wave train of nonlinear inertia-gravity waves of limiting amplitude appears behind a downstream hydraulic jump.
Experimental detection of rotational non-Boltzmann distribution in supersonic free molecular nitrogen flows
Authors: Mori Hideo , Niimi Tomohide , Akiyama Isao , Tsuzuki Takumi
Published: November 2005

In the present study, we measure the rotational population in supersonic nitrogen-free jets using a resonantly enhanced multiphoton ionization (REMPI) method [Chem. Phys. Lett. 115, 492 (1985)], which is not influenced by secondary electrons, unlike the electron beam method. Nitrogen ions are detected as a REMPI signal and its spectra, depending on the wavelength of an irradiated laser beam, are analyzed to measure rotational temperature through the Boltzmann plot. Nitrogen gas expands into a vacuum chamber from a sonic nozzle with a D=0.50mm diameter, setting P0∙D (where P0 is the source pressure), depending inversely on the nozzle Knudsen number, at 15Torrmm or lower. For P0∙D=15Torrmm, the rotational temperature distribution along the centerline of the jet, measured by using only the linear portion of the Boltzmann plot lying at smaller rotational quantum numbers, coincides with Marrone’s data [Phys. Fluids 10, 521 (1967)] measured by electron beam fluorescence, and the rotational relaxation rate ZR calculated by the relaxation equation results in 1.3. However, the non-Boltzmann rotational distribution appears evidently in supersonic free molecular nitrogen flows for P0∙D⩽15Torrmm, in good agreement with the simulation results of the combination of the classical trajectory calculation and the direct simulation Monte Carlo method by Koura [Phys. Fluids 14, 1689 (2002)]. As a decrease in P0∙D, the deviation from the Boltzmann distribution and the partial freezing of the population arise more upstream.
Supression of carrier recombination in semiconductor lasers by phase-space filling
Authors: Hader J. , Moloney J. V. , Koch S. W.
Published: November 2005

A fully microscopic model is used to calculate the carrier losses in semiconductor lasers due to Auger recombination and spontaneous emission. The results show that the commonly assumed power-law dependencies of these loss processes on the plasma density break down already below the transparency point. Most significantly, the density dependent increase of the spontaneous emission changes from quadratic to linear, while the increase of the Auger recombination is reduced from cubic to approximately quadratic or even less.
Tunable thermal hysteresis in CoGd alloys
Authors: Demirtas S. , Camley R. E. , Koymen A. R.
Published: November 2005

We show that tunable magnetic thermal hysteresis can be realized for a simple ferrimagnetic CoGd alloy. The magnetization of a Co0.8Gd0.2 alloy shows a bow-tie curve as a function of temperature, which indicates supercooled and superheated phase transitions. The width of the magnetic thermal hysteresis can be tuned by an external magnetic field, with values of 190 K at fields near 100 Oe and values of 20 K near 400 Oe. Experimental results are in reasonable agreement with theoretical calculations.
Neutron scattering and modeling of dipole-field-induced spin disorder in Nanoperm
Authors: Vecchini C. , Moze O. , Suzuki K. , Pranzas P. K. , Weissmüller J. , Michels A.
Published: November 2005

We present magnetic-field-dependent small-angle neutron scattering data for the ferromagnetic nanocomposite Nanoperm (Fe89Zr7B3Cu1). The spin-misalignment scattering in the approach-to-saturation regime unexpectedly reveals pronounced lobes of high intensity at angles ±30−40° relative to the magnetic-field axis. Based on numerical calculations, the four-fold angular symmetry of the scattering pattern can be explained in terms of local spin misalignment, which originates from dipolar stray fields due to the mismatch of the saturation-magnetization values between the bcc Fe particles and the amorphous magnetic matrix.
Quantitative Determination of Aqueous Dodecatungstophosphoric Acid Speciation by NMR Spectroscopy
Authors: Smith Bradley J. , Patrick Vincent A.
Published: November 2005

The speciation and equilibria during base decomposition of α-[PW12O40]3– have been determined using 31P and 183W NMR spectroscopy over the pH range 0.7–13.5. NMR spectroscopy was used to directly observe the polytungstate species in aqueous solution at high concentration (0.25 mol L–1) and follows the progressive decomposition of [PW12O40]3– to WO42– and PO43–. It was found unexpectedly in the pH range 1.2–2.3 that [PW12O40]3– did not decompose directly to [PW11O39]7– but first formed an equilibrium with [P2W18O62]6–, [P2W21O71]6–, and some new, stable, intermediate species before converting into α-[PW11O39]7–.
Synthesis and Electrochemical Characterization of New Thioether- and Ferrocene-Containing Copolymers
Authors: Baker Murray V. , Lu Jinzhen , Issa Touma B. , Singh Pritam , Strauch Jelica
Published: November 2005

Random copolymers containing both ferrocene groups and thioether groups were synthesized by free-radical copolymerization of vinylferrocene and 2-(methylthio)ethyl methacrylate, and the random nature of the copolymerization was confirmed by spectroscopic studies. Copolymers with ferrocene-to-thioether ratios of 8 : 1 and 1.2 : 1 were used to modify the surfaces of gold electrodes, and the behaviours of the resulting surface-modified electrodes were investigated by cyclic voltammetry. The SMEs based on the copolymers showed superior stability compared to SMEs based on poly(vinylferrocene), with the most stable SMEs being formed from the copolymer with the higher proportion of thioether groups.
Biomimetic Synthesis of Ag2CrO4 Quasi-Nanorods and Nanowires by Emulsion Liquid Membranes
Authors: Liu Lu , Wu Qingsheng , Ding Yaping , Liu Huajie , Qi Jingyu , Liu Qian
Published: November 2005

Semiconductor Ag2CrO4 quasi-nanorods and nanowires have been successfully prepared through novel emulsion–liquid membrane technology. The membrane phase in this system consists of Span-80 as the surfactant, N7301 as the carrier (or free carrier), and kerosene as the solvent. The internal aqueous phase is 0.1 M AgNO3 and the external aqueous phase is 0.1 M K2Cr2O7. Under the conditions of Roi = 2.0, Rew = 0.5, [Span-80] = 6% (v/v), and room temperature, Ag2CrO4 quasi-nanorods with diameters of 180–300 nm and lengths of up to 2300 nm, or nanowires with diameters of 15–25 nm and lengths of up to 1000 nm, were obtained in the presence or absence of 5% (v/v) N7301, respectively. X-Ray diffraction and transmission electron microscopy were used to characterize the structure and morphology of the Ag2CrO4 quasi-nanorods and nanowires. In addition, the photoluminescence spectrum showed strong emissions.
DNA Scission Chemistry and EPR Studies of Four New Bis(2,6-Dimethoxyhydroquinone - 3-Mercaptoacetic Acid) - Peptide Conjugates
Authors: Song Yu-Fei
Published: November 2005

In an effort to investigate the use of short peptide chains as carriers of new antitumour agents, four tripeptide cytotoxic agent conjugates, namely DMQ–MA–Lys(DMQ–MA)–Lys(Cbz)–Arg–OMe, DMQ–MA–Lys(DMQ–MA)–Phe–Arg–OMe, DMQ–MA–Lys(DMQ–MA)–Ile–Arg–OMe, and DMQ–MA–Lys(DMQ–MA)–Val–Arg–OMe, were synthesized. The cytotoxic agent conjugated to the N-terminal, and the ξ-amino group of lysine of the tripeptides was 2,6-dimethoxyhydroquinone–3-mercaptoacetic acid (DMQ–MA). The tripeptides were synthesized by coupling protected amino acid residues in solution according to Pfp/DCC methods (where Pfp refers to pentafluorophenol and DCC refers to N,N′-dicyclohexylcarbodiimide). DNA scission chemistry showed that these compounds were able to cleave supercoiled DNA into open-circular form in drug concentrations as low as 5–20 μM without addition of H2O2 or UV irradiation. DNA cleavage was clearly inhibited when hydroxyl radical scavengers such as glycerol and sodium benzoate were added to the reaction system. When the drugs were added to rhodamine B, the UV absorbance and fluorescence intensity of rhodamine B decreased quickly due to the degradation caused by the hydroxyl radicals. Electron paramagnetic resonance (EPR) experiments employing the spin-trap agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) showed that the signal intensity of the hydroxyl radicals generated from these newly synthesized DMQ–MA–peptide compounds was a non-linear function of ascorbic acid concentration. Deoxyribonucleic acid binding constants of these compounds were in the 104 M–1 range. It was concluded that DNA cleavage was not related to the ability of these drugs to produce hydroxyl radicals exclusively; indeed, it was related to their ability to produce various radicals and reactive species.
Tp*WIVO(S2CNEt2): the Missing Member of the Series
Authors: Eagle Aston A. , Young Charles G. , Tiekink Edward R. T.
Published: November 2005

The missing member of the series Tp*ME(S2CNEt2) (M = Mo, W; E = O, S), namely Tp*WO(S2CNEt2), has been synthesized by oxygen-atom transfer from pyridine N-oxide to Tp*W(S2CNEt2)(CO)2. The air-stable, blue-purple complex was characterized by microanalysis, mass spectrometry (m/z 645 (100%), [M]+), cyclic voltammetry, and IR and 1H NMR spectroscopy. Solutions of the complex are dichroic and solvatochromic. The X-ray crystal structure of the complex revealed a six-coordinate, distorted octahedral complex with axial oxo (W = O 1.680(5) Å), ‘equatorial’ dithiocarbamate (W—S 2.3962(17) and 2.4102(17) Å), and facial tridentate Tp* ligands. The synthesis and characterization of Tp*WCl3 are also reported.
The Synthesis of 3-O-(β-D-Glucopyranosyl)- and 3-O-(β-Laminaribiosyl)-isofagomines, Potent Inhibitors of a 1,3-β-D-Glucan endo-Hydrolase
Authors: Macdonald James M. , Hrmova Maria , Fincher Geoffrey B. , Stick Robert V.
Published: November 2005

The glycosylation of 4,6-O-benzylidene-N-benzyloxycarbonylisofagomine with a D-glucosyl and a laminari-biosyl trichloroacetimidate has given, after removal of protecting groups, 3-O-(β-D-glucopyranosyl)- and 3-O-(β-laminaribiosyl)-isofagomines. Also included are similar glycosylations of a related tetrahydrooxazine. 3-O-(β-D-Glucopyranosyl)- and 3-O-(β-laminaribiosyl)-isofagomines acted as potent inhibitors of a barley 1,3-β-D-glucan endo-hydrolase, with ID50 values of 7.8 and 3.1 μM, respectively.
ω-Conotoxins and Approaches to Their Non-Peptide Mimetics
Authors: Baell Jonathan B. , Duggan Peter J. , Lok Y. Phei
Published: November 2005

ω-Conotoxins are an interesting class of naturally occurring peptides that induce dramatic effects on the central nervous system (CNS). They have been shown to interfere with the normal function of neuronal calcium channels and can act as non-addictive analgesics. The usual problems associated with the delivery of peptidic therapeutics have led to efforts to produce non-peptidic mimetics of ω-conotoxins. Identification of the key amino-acid residues responsible for the physiological effects of the ω-conotoxins MVIIA and GVIA has allowed the design and synthesis of compounds that bind to neuronal calcium channels at low micromolar concentrations. These mimics bear the side chains of three amino acids that project from central scaffolds in similar ways to critical side chains of the conotoxins they simulate. Several useful leads have been identified, some of which show selectivity for N-type calcium channels.
In vitro sugar uptake by grapefruit (Citrus paradisi) juice-sac cells
Authors: Huberman Moshe , Zehavi Uri , Stein Wilfred D. , Etxeberria Ed , Goren Raphael
Published: November 2005

To further our understanding of the mechanisms of sugar uptake and accumulation into grapefruit (Citrus paradisi Macf. cv. Marsh seedless), the patterns of uptake and utilisation of sucrose, glucose and fructose by Citrus juice cells was investigated. Analyses were conducted on sliced juice sacs that were incubated in radioactive [14C]-sugar solutions with unlabelled sugars, in the presence or absence of metabolic inhibitors. Both hexoses demonstrated an initial uptake peak in December and a second uptake peak in February–March. From March through April the rates of sucrose uptake increased to levels comparable to those of glucose and fructose. Sucrose and its moieties fructose and glucose entered the juice cells of Citrus juice fruit by an insaturable, and mostly by an independent, process. However, NaN3 and carbonylcyanide m-chlorophenylhydrazone (CCCP) produced slight inhibition of these processes. Cells took up hexoses at a greater rate than sucrose, with accumulation reaching a plateau by 4–8 h, and then continuing unabated, in the case of glucose, for 42 h. Uptake of all three sugars increased linearly in the range of sugar concentrations tested, which extended from 0.01 to 320 mm, denoting an insaturable system for sugar uptake. 14CO2 evolution was relatively low in all the experiments, the lowest evolution being recorded when the uptake of [14C]-sucrose was studied, while the highest 14CO2 evolution was recorded when the uptake of [14C]-glucose was studied. The data demonstrate a preferential utilisation of glucose over fructose and sucrose. In all the experiments, the two metabolic inhibitors significantly inhibited the decarboxylation of the three sugars.
Viewpoint: Carbon isotope effect predictions for enzymes involved in the primary carbon metabolism of plant leaves
Authors: Tcherkez Guillaume , Farquhar Graham D.
Published: November 2005

Carbon isotope effects of enzymes involved in primary carbon metabolism are key parameters in our understanding of plant metabolism. Nevertheless, some of them are poorly known because of the lack of in vitro experimental data on purified enzymes. Some studies have focused on theoretical predictions of isotope effects. Here we show how quantum chemical calculations can be adapted for calculation of isotope effects for the Rubisco-catalysed carboxylation and oxygenation reactions and the citrate synthase reaction. The intrinsic isotope effect of the carboxylation by Rubisco appears to be much smaller than previously thought, being close to the overall isotope effect of the reaction that is, between 25 and 30 per mil. The same applies to the enzyme citrate synthase, that catalyses the first step of the Krebs cycle, with an isotope effect of around 23 per mil. Combined with the isotope effects of equilibrium reactions calculated with β-factors, the Krebs cycle then has an overall isotope effect that depletes organic acids in 13C.
Reproduction in sympatric lizards: comparison of two species of Ctenotus (Scincidae) in south-eastern Australia
Authors: Taylor Jennifer E.
Published: November 2005

The scincid lizards Ctenotus robustus and C. taeniolatus occur sympatrically in regenerating, sand-mined areas in the Port Stephens–Myall Lakes region, coastal New South Wales, Australia. They are absent from the unmined open forest of the area. The reproductive characteristics of these two species were compared. Males reached sexual maturity at a smaller snout–vent length (SVL) than females in C. robustus (72 mm v. 78 mm) and C. taeniolatus (49 mm v. 52 mm). Males were reproductive from August to December and maximum testis volume in both species occurred in early spring; minimum testis volume was recorded in early autumn. Females of both species contained yolking follicles or eggs from October to January (spring–summer). Clutch size in C. robustus (4–9) did not differ significantly from that in C. taeniolatus (2–7) when SVL was accounted for. Both species laid eggs in nests dug 4–5 cm deep in open sandy areas with sparse vegetation, and nesting requirements might explain their absence from open forest. At hatching, C. robustus averaged 35.9 mm SVL and C. taeniolatus averaged 29.9 mm SVL. Hatchlings of both species were at field sites from mid-January to early April. Overall, reproductive characteristics of C. robustus and C. taeniolatus were generally similar.
Altitudinal distribution and abundance of microhylid frogs (Cophixalus and Austrochaperina) of north-eastern Australia: baseline data for detecting biological responses to future climate change
Authors: Shoo L. P. , Williams Y.
Published: November 2005

Extensive abundance surveys of microhylid frogs across altitudinal gradients within the Wet Tropics rainforests of north-eastern Australia were undertaken. Detailed patterns of abundance were resolved for nine microhylid species exhibiting differing associations within the altitudinal gradient. The position of altitudinal range boundaries was found to be largely consistent with previous accounts in the literature, providing confidence in established limits to species distributions. Microhylid frogs, in particular those species restricted to mountaintops, are considered among other endemic rainforest vertebrates within the region to be one of the groups most immediately threatened by climate change. The combined results establish important baseline data for assessing the impacts of climate change, including altitudinal shifts in distribution and localised declines in abundance, on microhylid frogs in the region.
Effects of diet change on carbon and nitrogen stable-isotope ratios in blood cells and plasma of the long-nosed bandicoot (Perameles nasuta)
Authors: Klaassen Marcel , Thums Michele , Hume Ian D.
Published: November 2005

Carbon (C) and nitrogen (N) stable isotopes offer a powerful tool for assessing the extent of tissue assimilation of dietary components. However, the method relies on knowledge of diet–tissue isotopic discrimination and how quickly diet shifts become apparent in various tissues. In the present study, blood plasma and blood cells, tissues that are easily obtained under field conditions, were used to validate the stable isotope method over a period of 4–5 weeks using captive long-nosed bandicoots (Perameles nasuta). Diet–tissue discrimination effects appeared to be small. For C, derived diet–tissue isotopic discriminations were 1.4‰ for blood plasma and –0.2‰ for blood cells. For N the values were 2.8‰ and 2.1‰, respectively, and were independent of the nitrogen content of the food. C and N turnover measurements in the blood plasma and cells of the bandicoots indicated that blood plasma provides dietary information integrated over a period of ~3 weeks, whereas blood cells give an impression of the assimilated diet over a period of as much as half a year. These turnover rates were low compared with the little information available for birds and eutherian mammals, and probably relate to the typically low metabolic rate of marsupials.
Breeding ecology and group dynamics of the apostlebird
Authors: Woxvold Iain A.
Published: November 2005

The breeding biology and social organisation of apostlebirds (Struthidea cinerea, Corcoracidae) were studied over three breeding seasons (August 1998 – January 2001) in southern central New South Wales. Group size ranged from 3 to 17 birds (mean 7.6), and the adult population was marginally male-biased (56.7%). Most new recruits (87.4%) into established groups were philopatric young hatched the previous season. Yearlings were lighter and had shorter wings than older birds. Formation of new groups was uncommon, and usually occurred (3 of 5) when a coalition departed following nest failure. Clutch size ranged from one to eight eggs (mean 3.9), and incubation lasted 15–17 days (mean 16.1). The time from hatching to fledging of the first chick was 17–22 days (mean 18.5). Most broods hatched asynchronously, resulting in a size hierarchy among chicks that was maintained until fledging. Relative weight at fledging was correlated with subsequent mortality. Most nests (80.4%) produced at least one fledgling (range 0–5, mean 2.6). Most groups (81.6%) were double-brooded. Predation resulted in 5 of 11 failures where the cause was known. Partial brood loss was higher among earlier nests, with nestling starvation the major cause. Groups raised 1–9 fledglings annually (mean 4.2), of which 0–7 (mean 2.6) survived to the following season. Group size was a significant determinant of seasonal productivity.
Noninvasive Characterization of Myocardial Blood Flow in Diabetic, Hypertensive, and Diabetic–Hypertensive Rats Using Spin‐Labeling MRI
Authors: ILTIS ISABELLE , KOBER FRANK , DALMASSO CHRISTIANE , COZZONE PATRICK J. , BERNARD MONIQUE
Published: November 2005

Objective: Microvascular alterations in the diabetic and hypertensive heart are likely to contribute to heart failure. In this work, myocardial blood flow and left ventricular function were measured in vivo in diabetic, hypertensive, and diabetic–hypertensive rats using MRI methods.

Methods: An 8‐week‐duration type 1 diabetes was induced by streptozotocin (STZ) in 8 Wistar‐Kyoto (WKY) rats (STZ) and in 11 spontaneously hypertensive (SHR) rats (STZ‐SHR). Fourteen WKY and 12 SHR served as control and hypertensive groups. Myocardial blood flow quantification was performed using an arterial spin‐labeling MRI method. Left ventricular morphology and function were assessed during the same experiment using cine‐MRI.

Results: Respective myocardial blood flow values for each group were 6.4 ± 1.1 (WKY), 6.0 ± 1.9 (STZ), 5.5 ± 1.3 (SHR), and 4.3 ± 0.9 mL· g−1· min−1 (STZ‐SHR). Myocardial blood flow was significantly decreased in STZ‐SHR rats compared with the other groups (p <.05, STZ‐SHR vs. all groups). Cine‐MRI showed morphological alterations in all pathological groups. No alteration of the ejection fraction was observed in the pathological groups.

Conclusion: Myocardial blood flow is altered in vivo before any sign of heart failure when rats have type 1 diabetes and hypertension simultaneously. When only one of the pathologies occurs, MBF does not vary significantly.
Protective Effects of Ischemic Preconditioning on the Intestinal Mucosal Microcirculation Following Ischemia–Reperfusion of the Intestine
Authors: MALLICK ISMAIL H. , YANG WENXUAN , WINSLET MARC C. , SEIFALIAN ALEXANDER M.
Published: November 2005

Objective: The small bowel villi are extremely sensitive to ischemia–reperfusion (IR) injury and a range of microcirculatory disturbances contribute to structural and functional changes. The aim of this study was to determine the protective effects of ischemic preconditioning (IPC) of the intestine on the mucosal villous microcirculation during IR injury of the intestine and whether heme oxygenase (HO) is involved in the protection.

Methods: Rats were allocated into 4 groups: (1) sham, (2) IR consisting of 30 min of ischemia followed by 2 h of reperfusion, (3) IPC, as in IR group, but preceded by 10 min of ischemia and 10 min of reperfusion, and (4) with administration of zinc protoporphyrin, an HO inhibitor before IPC and IR. The mucosa of an exteriorized segment of ileum was visualized. Mucosal perfusion index (MPI), red blood cell (RBC) velocity and leukocyte–endothelial interactions during reperfusion were assessed continuously using in vivo fluorescence microscopy. HO activity in the ileum was assessed at the end of the reperfusion period.

Results: IPC improved the MPI by 26% and the RBC velocity by 29% on comparison to IR. IR led to a 52% increase in leukocyte–endothelial interactions on comparison to IPC. The administration of zinc protoporphyrin reversed the beneficial effects of IPC. There was a two fold increase of HO activity in IPC compared to IR, whereas zinc protoporphyrin significantly reduced the HO activity.

Conclusions: IPC conferred a protective effect on the villous microcirculation possibly via HO and might prove to be an effective strategy for the amelioration of IR injury.
The Inositol Polyphosphate 5-Phosphatase, PIPP, Is a Novel Regulator of Phosphoinositide 3-Kinase-dependent Neurite Elongation
Authors: Ooms Lisa M. , Fedele Clare G. , Astle Megan V. , Ivetac Ivan , Cheung Vanessa , Pearson Richard B. , Layton Meredith J. , Forrai Ariel , Nandurkar Harshal H. , Mitchell Christina A.
Published: November 2005

The spatial activation of phosphoinositide 3-kinase (PI3-kinase) signaling at the axon growth cone generates phosphatidylinositol 3,4,5 trisphosphate (PtdIns(3,4,5)P3), which localizes and facilitates Akt activation and stimulates GSK-3β inactivation, promoting microtubule polymerization and axon elongation. However, the molecular mechanisms that govern the spatial down-regulation of PtdIns(3,4,5)P3signaling at the growth cone remain undetermined. The inositol polyphosphate 5-phosphatases (5-phosphatase) hydrolyze the 5-position phosphate from phosphatidylinositol 4,5 bisphosphate (PtdIns(4,5)P2) and/or PtdIns(3,4,5)P3. We demonstrate here that PIPP, an uncharacterized 5-phosphatase, hydrolyzes PtdIns(3,4,5)P3forming PtdIns(3,4)P2, decreasing Ser473-Akt phosphorylation. PIPP is expressed in PC12 cells, localizing to the plasma membrane of undifferentiated cells and the neurite shaft and growth cone of NGF-differentiated neurites. Overexpression of wild-type, but not catalytically inactive PIPP, in PC12 cells inhibited neurite elongation. Targeted depletion of PIPP using RNA interference (RNAi) resulted in enhanced neurite differentiation, associated with neurite hyperelongation. Inhibition of PI3-kinase activity prevented neurite hyperelongation in PIPP-deficient cells. PIPP targeted-depletion resulted in increased phospho-Ser473-Akt and phospho-Ser9-GSK-3β, specifically at the neurite growth cone, and accumulation of PtdIns(3,4,5)P3at this site, associated with enhanced microtubule polymerization in the neurite shaft. PIPP therefore inhibits PI3-kinase-dependent neurite elongation in PC12 cells, via regulation of the spatial distribution of phospho-Ser473-Akt and phospho-Ser9-GSK-3β signaling.
Proteolysis of Cortactin by Calpain Regulates Membrane Protrusion during Cell Migration
Authors: Perrin Benjamin J. , Amann Kurt J. , Huttenlocher Anna
Published: November 2005

Calpain 2 regulates membrane protrusion during cell migration. However, relevant substrates that mediate the effects of calpain on protrusion have not been identified. One potential candidate substrate is the actin binding protein cortactin. Cortactin is a Src substrate that drives actin polymerization by activating the Arp2/3 complex and also stabilizes the cortical actin network. We now provide evidence that proteolysis of cortactin by calpain 2 regulates membrane protrusion dynamics during cell migration. We show that cortactin is a calpain 2 substrate in fibroblasts and that the preferred cleavage site occurs in a region between the actin binding repeats and the α-helical domain. We have generated a mutant cortactin that is resistant to calpain proteolysis but retains other biochemical properties of cortactin. Expression of the calpain-resistant cortactin, but not wild-type cortactin, impairs cell migration and increases transient membrane protrusion, suggesting that calpain proteolysis of cortactin limits membrane protrusions and regulates migration in fibroblasts. Furthermore, the enhanced protrusion observed with the calpain-resistant cortactin requires both the Arp2/3 binding site and the Src homology 3 domain of cortactin. Together, these findings suggest a novel role for calpain-mediated proteolysis of cortactin in regulating membrane protrusion dynamics during cell migration.
L'Osservatore Romano and the Holocaust, 1939–1945
Authors: Zuccotti Susan
Published: November 2005

The frequent anti-Jewish articles in the official Vatican newspaper in the 1930s disappeared during the papacy of Pius XII (1939–1958). The research below shows that, even so, L'Osservatore Romano did not publicize the destruction of Europe's Jews during the Holocaust and remained reticent on other German atrocities. It did report Soviet cruelties and aggression. Even after the liberation of Rome in June 1944, the newspaper failed to denounce the ongoing genocide. It did, however, print the pope's three speeches that included expressions of compassion for those suffering because of “nationality and descent,” his two encyclicals mentioning the unity of the human family, and several articles objecting to biological racism. After the roundup of 1,259 Roman Jews on October 16, 1943, it referred twice to the pope's universal charity without distinction of “nationality, religion, or descent,” while in December it objected to arrests of Jews by Italians; the paper suffered no serious consequences. The author argues that L'Osservatore Romano could have done more.
The Senior Leadership Cadre of the Geheime Feldpolizei, 1939–1945
Authors: Brown Paul B.
Published: November 2005

In the Nuremberg International Military Tribunal proceedings, the Geheime Feldpolizei (GFP) was adjudged not to have been a criminal organization as defined “within the charge of criminality contained in the Indictment.” The tribunal did, however, determine that GFP personnel committed both war crimes and crimes against humanity “on a wide scale.” Despite this judgment, senior GFP officials were never prosecuted for crimes committed by GFP personnel. This article provides a detailed analysis of forty-five senior GFP leaders, based in part on hitherto unavailable primary sources. It examines four main areas: the leaders' social origins and career patterns; the role of the GFP in the Vernichtungskrieg during the invasion of the Soviet Union; the senior GFP officials' political affiliations and attempts to influence postwar denazification; and their postwar careers.