bluuebunny/crossref_metadata_2025 huggingface dataset:
Rheo-optical studies of carbon nanotube suspensions
Authors: Fry D. , Langhorst B. , Wang H. , Becker M. L. , Bauer B. J. , Grulke E. A. , Hobbie E. K.
Published: January 2006

We use a polarization-modulation technique to investigate the optical anisotropy of multi- and single-wall carbon nanotubes suspended in a variety of solvents under simple shear flow. Measurements of birefringence and dichroism are performed as a function of shear rate, tube concentration, and solvent viscosity. At fixed volume fraction, the anisotropy increases with increasing shear stress due to enhanced flow alignment. At fixed shear stress, the anisotropy increases with volume fraction due to rotational excluded-volume interactions. By considering the rotational diffusivity as a function of nanotube length, diameter, concentration, and solvent viscosity, we demonstrate a leading-order scaling relation for the optical anisotropy in terms of rotary Peclet number Pe. At low Pe, our results are in qualitative agreement with the theoretical predictions of Doi and Edwards. At high Pe, our data suggest that the degree of nanotube alignment scales as Pe1∕6.
Shear-induced parallel-to-perpendicular orientation transition in the amphiphilic lamellar phase: A nonequilibrium molecular-dynamics simulation study
Authors: Guo Hongxia
Published: January 2006

The present work is devoted to a study of the shear-induced parallel-to-perpendicular orientation transition in the lamellar system by the large-scale nonequilibrium molecular-dynamics (NEMD) simulation. An effective generic model-A2B2 tetramer for amphiphilies is used. The NEMD simulation produces unambiguous evidence that undulation instability along the vorticity direction sets in well above a critical shear rate and grows in magnitude as the shear rate is further increased. At a certain high shear rate, the coherent undulation instability grows so large that defects are nucleated and the global lamellar monodomain breaks into several aligned lamellar domains. Subsequently layers in these domains rotate into the perpendicular orientation with the rotation of chains towards the y direction, merge into a global perpendicular-aligned lamellar monodomain, and organize into a perfect well-aligned perpendicular lamellar phase by the migration and annihilation of edge dislocations and disclinations. The macroscopic observable viscosity as a function of time or shear rate is correlated with the structural response such as the mesoscopic domain morphology and the microscopic chain conformation. The onset of undulation instability concurs with the start-up of shear-thinning behavior. During the orientation transformation at the high shear rate, the complex time-dependent thixotropic behavior is observed. The smaller viscosity in the perpendicular lamellar phase gives an energetic reason for the shear-induced orientation transition.
Dissociative ion-pair formation in collisions of fast potassium atoms with benzene and fluorobenzene
Authors: Limão-Vieira P. , Moutinho A. M. C. , Los J.
Published: January 2006

Using a crossed molecular-beam technique, electron transfer is studied in collisions of fast potassium atoms with benzene and fluorobenzene molecules. The negative fragment ions formed in the collision region are extracted by a pulsed voltage, and their masses and energy release distributions analyzed by a time-of-flight (TOF) method. The dominant fragment from C6H5F is F−. The phenyl ring fragments CH− and C2H− are also observed but with lower intensities. In the case of C6H6 the dominant anionic specie is C2H−. The kinetic-energy release distributions of the various fragments are derived from the width and shapes of the TOF peaks in the spectrum.
Formal relations connecting different approaches to calculate relativistic effects on molecular magnetic properties
Authors: Zaccari D. G. , Ruiz de Azúa M. C. , Melo J. I. , Giribet C. G.
Published: January 2006

In the present work a set of formal relations connecting different approaches to calculate relativistic effects on magnetic molecular properties are proven. The linear response (LR) within the elimination of the small component (ESC), Breit Pauli, and minimal-coupling approaches are compared. To this end, the leading order ESC reduction of operators within the minimal-coupling four-component approach is carried out. The equivalence of all three approaches within the ESC approximation is proven. It is numerically verified for the NMR nuclear-magnetic shielding tensor taking HX and CH3X (X=Br,I) as model compounds. Formal relations proving the gauge origin invariance of the full relativistic effect on the NMR nuclear-magnetic shielding tensor within the LR-ESC approach are presented.
Coarse-grained interaction potentials for polyaromatic hydrocarbons
Authors: von Lilienfeld O. A. , Andrienko Denis
Published: January 2006

Using Kohn-Sham (KS) density-functional theory, we have studied the interaction between various polyaromatic hydrocarbon molecules. The systems range from monocyclic benzene up to hexabenzocoronene (hbc). For several conventional exchange-correlation functionals total potential-energy curves of interaction of the π-π stacking hbc dimer are reported. It is found that all pure local density or generalized gradient approximated functionals yield qualitatively incorrect predictions regarding structure and interaction. Inclusion of a nonlocal, atom-centered correction to the KS Hamiltonian enables quantitative predictions. The computed potential-energy surfaces of interaction yield parameters for a coarse-grained potential, which can be employed to study discotic liquid-crystalline mesophases of derived polyaromatic macromolecules.
C n films (n=50, 52, 54, 56, and 58) on graphite: Cage size dependent electronic properties
Authors: Löffler Daniel , Jester Stefan S. , Weis Patrick , Böttcher Artur , Kappes Manfred M.
Published: January 2006

Novel semiconducting materials have been prepared under ultrahigh-vacuum conditions by soft-landing mass-selected Cn+ (50⩽n<60; even n) on highly oriented pyrolytic graphite surfaces at mean kinetic energies of 6eV. In all cases, Cn films grow according to the Volmer-Weber mechanism: the surface is initially decorated by two-dimensional fractal islands, which in later deposition stages become three-dimensional dendritic mounds. We infer that Cn aggregation is governed by reactive sites comprising adjacent pentagons (or heptagons) on individual cages. The resulting covalent cage-cage bonds are responsible for the unusually high thermal stability of the films compared to solid C60. The apparent activation energies for intact Cn sublimation range from 2.2eV for C58 to 2.6eV for C50 as derived from thermal desorption spectra. All Cn films exhibit a common valence-band ultraviolet photoelectron spectroscopy spectral feature located around the center of a broad highest occupied molecular-orbital (HOMO)-derived band (EB∼2.5eV). This feature has been assigned to Cn units covalently linked to each other in polymeric structures. To within experimental accuracy, the same work function (4.8eV) was determined for thick films of all Cn studied. In contrast, “HOMO” ionization potentials were cage size dependent and significantly lower than that obtained for C60. C58 exhibited the lowest HOMO (6.5eV). Band gaps of Cn films have been determined by depositing small amounts of Cs atoms onto the topmost film layer. HOMO-lowest unoccupied molecular-orbital-derived band gaps between 0.8eV (C52) and 1.8eV (C50) were observed, compared to 1.5eV for solid C60.
Finite-element implementation for electron transport in nanostructures
Authors: Havu P. , Havu V. , Puska M. J. , Hakala M. H. , Foster A. S. , Nieminen R. M.
Published: January 2006

We have modeled transport properties of nanostructures using Green’s-function method within the framework of the density-functional theory. The scheme is computationally demanding, so numerical methods have to be chosen carefully. A typical solution to the numerical burden is to use a special basis-function set, which is tailored to the problem in question, for example, the atomic-orbital basis. In this paper we present our solution to the problem. We have used the finite-element method with a hierarchical high-order polynomial basis, the so-called p elements. This method allows the discretation error to be controlled in a systematic way. The p elements work so efficiently that they can be used to solve interesting nanosystems described by nonlocal pseudopotentials. We demonstrate the potential of the implementation with two different systems. As a test system a simple Na-atom chain between two leads is modeled and the results are compared with several previous calculations. Secondly, we consider a thin hafnium dioxide (HfO2) layer on a silicon surface as a model for a gate structure of the next generation of microelectronics.
Investigation of regimes of wire array implosion on the 1MA Zebra accelerator
Authors: Ivanov V. V. , Kantsyrev V. L. , Sotnikov V. I. , Fedin D. A. , Astanovitskiy A. L. , Le Galloudec B. , Nalajala V. , Shrestha I. , Cowan T. E. , Jones B. , Coverdale C. A. , Deeney C. , LePell P. D.
Published: January 2006

Implosion of wire arrays was investigated at the 1MA Zebra accelerator by multiframe laser probing and gated x-ray self-emission diagnostics. Different regimes of implosion were observed in Al and Cu wire arrays. Implosion of Al loads with masses of 33–37μg∕cm produces a dense pinch 1–1.5mm in diameter. Strong instabilities are observed in the Z pinch at the time of stagnation. Implosion of “overmassed” loads produces a plasma column 3–4mm in diameter with a core. The plasma column does not collapse during the x-ray pulse. The core of the plasma column is not subjected to the kink instability and transforms to a chain of dense spots in the later stage. Different regimes of implosion were observed in Al 8×15μm loads presumably due to variations in the current pulse and load conditions. Observed regimes are compared to three-dimensional hybrid simulation of ideal and nonideal magnetohydrodynamics modes of implosion.
Dusty plasmas in fusion devices
Authors: de Angelis U.
Published: January 2006

Recent results from the theory of dusty plasmas are considered in the parameter regime close to the walls, divertor of magnetic confinement fusion devices, in an attempt to establish the effects that can be important to plasma operation and performance. The dust charge and dust-dust interaction potential are considered and it is shown that long-range attraction of negatively charged dust particles is possible. The ion-dust scattering and drag force are calculated in the linear and nonlinear regimes, and it is shown that scattering through waves can enhance the drag force on dust particles by orders of magnitude, which can be important for dust transport and removal. The effects of charged dust on wave propagation and scattering of radiation are discussed and it is shown that an instability due to dust charge fluctuations, leading to stochastic heating of dust particles, can effectively grow for submicron dust particles.
Oscillator strengths of helium computed using Monte Carlo methods
Authors: Alexander S. A. , Coldwell R. L.
Published: January 2006

We have optimized trial wave functions for the three lowest states of the helium atom with symmetry S1, P1, D1, S3, P3, and D3 using variational Monte Carlo methods. With these wave functions we then computed dipole oscillator strengths for the S1-P1, P1-D1, S3-P3, and P3-D3 transitions using the length, velocity, and acceleration forms. Our values are in good agreement with the best results found in the literature.
Methyl iodide clusters observed in gas phase by infrared cavity ring-down spectroscopy: The CH3 bending mode at 8μm
Authors: Ito Fumiyuki
Published: January 2006

Infrared spectra of methyl iodide clusters produced in a supersonic jet have been observed in the CH3 bending region at 8μm by cavity ring-down spectroscopy. The dependence of the spectral features on the mixing ratio of CH3I to He and on the stagnation pressure has allowed us to assign the absorption peaks, with the help of the previous results obtained by matrix-isolation technique [Ito et al., Chem. Phys. Lett. 343, 185 (2001)] and infrared cavity ring-down spectroscopy in the C–H stretching region [Ito et al., Chem. Phys. 286, 337 (2003)]. Ab initio calculations at the MP2 level have been carried out up to tetramer to confirm the assignments. It has been found that the frequency shifts upon clustering (relative to monomer) observed in the bending region are not monotonic, in contrast to those in the C–H stretching region. The observed frequency shifts are discussed in terms of dispersion interaction and its variation upon vibrational excitation.
Photoelectron spectroscopy of AlnD2− (n=3–15): Observation of chemisorption and physisorption of dideuterium on aluminum cluster anions
Authors: Cui Li-Feng , Li Xi , Wang Lai-Sheng
Published: January 2006

Photoelectron spectroscopy is used to investigate aluminum dideuteride cluster anions, AlnD2− (n=3,6–15), produced by laser vaporization of a pure Al target with a D2-seeded helium carrier gas. Comparison between the well-resolved photoelectron spectra of AlnD2− and Aln− reveals the nature of interactions between D2 and Aln−. Depending on the size of the Aln− clusters and their electronic structure, three types of AlnD2− species are observed, dideuteride (dissociative chemisorption), molecular chemisorption, and physisorption. Striking spectral similarities are observed between photoelectron spectra of AlnD2− and Aln− for n=9, 11, 13, and 15, suggesting that D2 is physisorbed on these closed-shell Aln− clusters. For AlnD2− with n=3, 6, 7, and 10, completely different spectra are observed in comparison with the corresponding Aln− clusters, suggesting that the AlnD2− species may be characterized as dideuterides. For AlnD2− with n=8, 12, and 14, in which the Aln− clusters are open shell, the D2 is characterized as chemisorption on the basis of spectral shifts and similarities relative to those of the corresponding Aln− clusters.
Investigation of edge pedestal structure in DIII-D
Authors: Stacey W. M. , Groebner R. J.
Published: January 2006

A calculation based on the requirements of particle, momentum and energy conservation, conductive heat transport, and atomic physics resulting from a recycling and fueling neutral influx was employed to investigate the experimental density, temperature, rotation velocities, and radial electric field profiles in the edge of three DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] high-confinement-mode plasmas. The calculation indicated that the cause of the pedestal structure in the density was a momentum balance requirement for a steep negative pressure gradient to balance the forces associated with an edge peaking in the inward pinch velocity (caused by the observed edge peaking in the radial electric field and rotation velocity profiles) and, to a lesser extent, in the outward radial particle flux (caused by the ionization of recycling neutrals). Thermal and angular momentum transport coefficients were inferred from experiment and compared with theoretical predictions, indicating that thermal transport coefficients were of the magnitude predicted by neoclassical and ion-temperature-gradient theories (ions) and electron-temperature-gradient theory (electrons), but that neoclassical gyroviscous theory plus atomic physics effects combined were not sufficient to explain the inferred angular momentum transfer rate throughout the edge region.
Effect of electrostatic plasma oscillations on the kinetic energy of a charged macroparticle
Authors: Vaulina O. S. , Vladimirov S. V. , Repin A. Yu. , Goree J.
Published: January 2006

The stochastic energy acquired by an isolated charged macroparticle (“dust” particle) due to electrostatic fluctuations of a weakly ionized plasma is investigated. Analytic relations are derived and numerical modeling of the problem for the conditions close to those of typical laboratory experiments in a complex dusty plasma is done. The study demonstrates that the kinetic energy of a dust particle, induced by the considered effect, can significantly exceed the temperature of the background gas. The most important contribution to the energy acquired by the macroparticle is due to the ion plasma component.
Crack-free highly reflective AlInN∕AlGaN Bragg mirrors for UV applications
Authors: Feltin E. , Carlin J.-F. , Dorsaz J. , Christmann G. , Butté R. , Laügt M. , Ilegems M. , Grandjean N.
Published: January 2006

We report the growth of highly reflective distributed Bragg reflectors (DBRs) in the UV region using the Al0.85In0.15N∕Al0.2Ga0.8N lattice-matched system. The DBRs were deposited on nearly strain-free Al0.2Ga0.8N templates to avoid strain-induced structural degradations. The appearance of cracks was then completely suppressed. The DBRs exhibit a reflectivity higher than 99% at a wavelength as short as ∼340nm and a stop band width of 215meV (20nm).
Electrostatic potential fluctuations in a Maxwellian plasma
Authors: Hazeltine R. D. , Lowrey J. D.
Published: January 2006

The spatial correlation function of a Maxwellian plasma with perturbations arising in the electrostatic potential due to random ion density fluctuations is examined. The entropy is found from the one-particle distribution function using the Shannon formula and then, using the Einstein method, the probability distribution for the electrostatic potential fluctuation is determined. This straightforward procedure is demonstrated to be a powerful tool in studying plasma correlation functions when the system entropy can be computed.
Membrane folding to achieve three-dimensional nanostructures: Nanopatterned silicon nitride folded with stressed chromium hinges
Authors: Arora William J. , Nichol Anthony J. , Smith Henry I. , Barbastathis George
Published: January 2006

Silicon nitride membranes were nanopatterned and then folded into three-dimensional (3D) configurations. The out-of-plane folding was achieved using stressed metal hinges. The concept of folding nanopatterned membranes into 3D shapes is referred to as nanostructured origami because of the similarity to the Japanese paper-art of origami, in which two-dimensional surfaces are folded into volumetric shapes. The stressed metal hinges were modeled analytically and compared to experiment. Experimental results demonstrated controllable folding of nanopatterned silicon nitride membranes.
Two-dimensional electron gas in InGaAs∕InAlAs quantum wells
Authors: Diez E. , Chen Y. P. , Avesque S. , Hilke M. , Peled E. , Shahar D. , Cerveró J. M. , Sivco D. L. , Cho A. Y.
Published: January 2006

We designed and performed low-temperature dc transport characterization studies on two-dimensional electron gases confined in lattice-matched In0.53Ga0.47As∕In0.52Al0.48As quantum wells grown by molecular beam epitaxy on InP substrates. The nearly constant mobility for samples with the setback distance larger than 50 nm and the similarity between the quantum and transport lifetime suggest that the main scattering mechanism is due to short range scattering, such as alloy scattering, with a scattering rate of 2.2ps−1. We also obtain the Fermi level at the In0.53Ga0.47As∕In0.52Al0.48As surface to be 0.36 eV above the conduction band, when fitting our experimental densities with a Poisson-Schrödinger model.
Strain-induced changes in the gate tunneling currents in p-channel metal–oxide–semiconductor field-effect transistors
Authors: Yang X. , Lim J. , Sun G. , Wu K. , Nishida T. , Thompson S. E.
Published: January 2006

Changes in the direct gate tunneling current are measured for strained p-channel metal–oxide–semiconductor field-effect transistors (MOSFETs) on (100) wafers for uniaxial and biaxial stress. Decreases/increases in the gate tunneling current for various stresses primarily result from repopulation into a subband with a larger/smaller out-of-plane effective mass. Strain-induced changes in the valence band offset between Si and SiO2 are also important but play a secondary role. Hole tunneling current is found to decrease for biaxial and uniaxial compressive stress and increase for biaxial tensile stress. The hole tunneling data is modeled using k∙p self-consistent solution to Poisson and Schrödinger’s equation, and a transfer matrix method.
Elastic stability and electronic structure of pyrite type PtN2: A hard semiconductor
Authors: Yu R. , Zhan Q. , Zhang X. F.
Published: January 2006

The elastic properties and electronic structure of PtN2 with the pyrite structure [PtN2(C2)] were studied with first-principles calculations. The crystal structure is demonstrated to be elastically stable with a lower energy than the metastable fluorite structure proposed before. The calculated shear modulus of 214 GPa suggests that PtN2(C2) is harder than some well-known hard materials such as TiN and SiC. The high elastic moduli are attributed to a stacking of corner-shared PtN6 octahedra bonded by strong N-N covalent bonding. In contrast to the metallic fluorite-type phase, PtN2(C2) is semiconducting with an indirect band gap.
Ni-dispersed fullerenes: Hydrogen storage and desorption properties
Authors: Shin Weon Ho , Yang Seong Ho , Goddard William A. , Kang Jeung Ku
Published: January 2006

Our study shows that the H2 storage media using Ni-dispersed fullerenes could be viable alternatives to reversible hydrogen storage. It is demonstrated that a single Ni coated on the fullerene surface can store up to three H2 molecules. Consequently, at high Ni coverage, Ni-dispersed fullerenes are considered to be the novel hydrogen storage media capable of storing ∼6.8wt%H2, thus exceeding the Department of Energy target (6.5 wt %) for automobile applications. Moreover, the H2 desorption activation barrier of 11.8kcal∕molH2 is ideal for many practical hydrogen storage applications.
Photosynthesis and characterization of Prussian blue nanocubes on surfaces of TiO2 colloids
Authors: Song Yan-Yan , Zhang Ke , Xia Xing-Hua
Published: January 2006

Prussian blue (PB) nanocubes were synthesized on the surface of titania (TiO2) colloids using two-step process with ultraviolet light illumination. The formation of PB nanocubes starts with its nucleation under strong ultraviolet light illumination and followed by a slow growth of the nuclei under low intensity natural light illumination. This kind of PB nanocube has a very low Curie temperature.
p
-type ZnO films with solid-source phosphorus doping by molecular-beam epitaxy
Authors: Xiu F. X. , Yang Z. , Mandalapu L. J. , Liu J. L. , Beyermann W. P.
Published: January 2006

Phosphorus-doped p-type ZnO films were grown on r-plane sapphire substrates using molecular-beam epitaxy with a solid-source GaP effusion cell. X-ray diffraction spectra and reflection high-energy electron diffraction patterns indicate that high-quality single crystalline (112¯0) ZnO films were obtained. Hall and resistivity measurements show that the phosphorus-doped ZnO films have high hole concentrations and low resistivities at room temperature. Photoluminescence (PL) measurements at 8 K reveal a dominant acceptor-bound exciton emission with an energy of 3.317 eV. The acceptor energy level of the phosphorus dopant is estimated to be 0.18 eV above the valence band from PL spectra, which is also consistent with the temperature dependence of PL measurements.
Bimolecular recombination in polymer/fullerene bulk heterojunction solar cells
Authors: Koster L. J. A. , Mihailetchi V. D. , Blom P. W. M.
Published: January 2006

Bimolecular recombination in organic semiconductors is known to follow the Langevin expression, i.e., the rate of recombination depends on the sum of the mobilities of both carriers. We show that this does not hold for polymer/fullerene bulk heterojunction solar cells. The voltage dependence of the photocurrent reveals that the recombination rate in these blends is determined by the slowest charge carrier only, as a consequence of the confinement of both types of carriers to two different phases.
Extraordinary optoconductance in metal-semiconductor hybrid structures
Authors: Wieland K. A. , Wang Yun , Ram-Mohan L. R. , Solin S. A. , Girgis A. M.
Published: January 2006

We provide the first demonstration of extraordinary optoconductance (EOC) in macroscopic metal-semiconductor hybrid structures fabricated from GaAs and In and the first example of an extraordinary transport (EXX) effect that is based on a perturbation of the relative bulk conductances of the constituents. Four-lead van der Pauw plate structures show a gain of order 500% in the optocondutance when shunted by In relative to unshunted devices. The dependence of the optocondutance on the position of a focussed Ar laser beam has been measured and is in agreement with a Gaussian broadened point charge model that accounts for the Dember effect. We also account quantitatively for the temperature dependence of the EOC.
Heterogeneity of a Cu47.5Zr47.5Al5 bulk metallic glass
Authors: Kim K. B. , Das J. , Baier F. , Tang M. B. , Wang W. H. , Eckert J.
Published: January 2006

Microstructural investigation of an as-cast Cu47.5Zr47.5Al5 bulk metallic glass (BMG) reveals two amorphous phases formed by liquid phase separation. The morphology of the phase separated amorphous regions is spherical with 10–20nm in size. These areas are homogeneously distributed throughout the sample. Moreover, a macroscopic heterogeneity also occurs along with the nano-scale liquid phase separation. The macroscopic heterogeneity can be distinguished from the different degree of the chemical fluctuations in the sample, and the existence of nano-scale crystals of less than 5nm in size. Presumably, both the macroscopic heterogeneity and the nano-scale phase separation enhance branching of the shear bands during deformation in the Cu47.5Zr47.5Al5 BMG.
Encapsulation for efficient electrical injection of photonic crystal defect mode surface-emitting lasers
Authors: Zhou Weidong
Published: January 2006

We propose and report an encapsulated photonic crystal concept for efficient electrical injection of photonic crystal surface-emitting lasers. Detailed rate equation analysis reveals a significant threshold current reduction by minimizing the surface-state-induced carrier loss. The impact of encapsulation on the photonic band gap is discussed for different encapsulation conditions. Experimental results on encapsulation process are reported, based on nanoparticle self-assembly.
Quantum oscillations of the luminescence from a modulation-doped GaAs∕InGaAs∕GaAlAs quantum well
Authors: Babiński Adam , Potemski M. , Shtrikman H.
Published: January 2006

Magnetospectroscopic studies of a modulation-doped GaAs∕InGaAs∕GaAlAs quantum well (QW) are presented. Oscillations of the photoluminescence (PL) intensity in magnetic field are investigated. Recombination processes giving rise to the PL are identified and their effect on the PL is established. It is shown how measurements of the oscillations can provide information on the density of the quasi-two-dimensional electron gas confined in the QW.
InSb
∕
AlInSb
quantum-well light-emitting diodes
Authors: Nash G. R. , Haigh M. K. , Hardaway H. R. , Buckle L. , Andreev A. D. , Gordon N. T. , Smith S. J. , Emeny M. T. , Ashley T.
Published: January 2006

We have investigated the room-temperature electroluminescent properties of InSb∕AlxIn1−xSb quantum-well light-emitting diodes. The maximum emission from diodes containing quantum wells occurred at significantly higher energies than the band gap of InSb. Close agreement between experimental and theoretical data confirms that recombination occurs within the quantum well.
Carrier-to-noise ratio enhancement of super-resolution near-field structure disks by Ag nanostructure
Authors: Arai T. , Kurihara K. , Nakano T. , Tominaga J. , Rockstuhl C.
Published: January 2006

The recording and retrieval characteristics of super-resolution near-field structure disks have been evaluated before and after the fabrication of a Ag-nanostructured film on the top dielectric layer, using a 405nm wavelength laser and a 0.65 numerical aperture lens system. The carrier-to-noise ratio for 100nm mark signals is significantly improved by applying the Ag-nanostructured film. The underlying mechanism for the enhancement depends on the top dielectric layer thickness. A simulation based on Mie theory shows good agreement with the measured reflectance spectrum for the Ag-nanostructured film.
Should Government be Stimulating Start-ups? An Assessment of the Scope for Public Intervention in New Venture Formation
Authors: Atherton Andrew
Published: January 2006

Although there is broad recognition amongst policymakers of the significance of new business start-ups to the economy, there is an ongoing debate in the research literature as to the feasibility and desirability of intervention at this stage of business development. Of particular concern is the extent to which government can target resources so that there is substantive additional impact arising from public intervention. Using the experiential ‘decision rules' of private investors, the author develops a broad framework for assessing the future potential of new ventures. Implications are considered for intermediaries working with all types of new venture prospect.
A Critical Analysis of Decentralisation and Local Economic Development: The Turkish Case
Authors: Özcan Gül Berna
Published: January 2006

Simple neoliberal approaches ignore the importance and power that the state has in making decentralization effective. This is shown through a critical analysis of local economic development in which evidence, from three projects in a second-rank Turkish industrial centre, Kayseri, was used. Turkey's recent moves from highly centralized systems of governance to neoliberal policies of economic devolution reveal a poor understanding of how the roles of state and its institutions operate. The findings illustrate that the control of narrow political interests distorts local priorities and projects, and many civil society groups remain ineffective in the face of local initiatives. The author concludes that decentralization without competent state administration is likely to aggravate social fracturing and to foster inequalities while, at the same time, failing to ameliorate public service and economic development.
How are SMEs Financed? Evidence from the Ghanaian Nontraditional Export Sector
Authors: Abor Joshua , Biekpe Nicholas
Published: January 2006

The study explored the determinants of small and medium-sized nontraditional exporters' choice of type of finance (formal or informal). The empirical results revealed a negative relationship between age and formal finance, suggesting that newer firms depend more on formal finance and less on informal finance. In addition, the study found positive and significant relationships between formal finance and size and growth of the firm. This suggests that larger and high-growth firms require more funds to finance their expansion and growth opportunities and therefore employ formal finance. Finally, the results of the study also indicated that the proportion of formal finance increases with increasing international activities, suggesting that, as firms engage more in international business, they employ more formal finance and less informal finance. Recommendations are made in this regard.
Do Enterprise Support Programmes Leave Women Holding the Baby?
Authors: Rouse Julia , Kitching John
Published: January 2006

Using data from a longitudinal study of working-class participants on a youth enterprise start-up programme in the United Kingdom, we examine whether programmes aimed at disadvantaged groups enable parents to combine business trading with childcare responsibilities. Business planning and programme selection practices ignored childcare, rendering it a solely private matter, invisible to public scrutiny. Yet this childcare barrier became both a cause and a consequence of business failure. Participants' experiences of combining trading and childcare varied by gender. All mothers and one father had complex strategies for synchronising trading and childcare responsibilities. However, these strategies soon collapsed, contributing to business closure. Most fathers relied on the childrens' mother to organise and conduct continuous care, but this was dependent on fathers becoming breadwinners through profitable trading which was not achieved. There is growing policy recognition of the importance of the childcare barrier to paid work for lower income families and for self-employed women in the United Kingdom. However, despite recent initiatives, severe constraints remain for working-class parents to start and manage a business. Several implications for policy are discussed.
Feed intake, body composition, and plasma metabolic hormones in Merino sheep that differ genetically in fleece weight or fibre diameter
Authors: Adams N. R. , Briegel J. R. , Greeff J. C. , Bermingham E. N.
Published: January 2006

Negative genetic correlations result in sheep selected for fleece weight having reduced fatness and reproductive turnoff. Both of these characteristics depend mainly on energy metabolism, but the links between wool growth and energy metabolism are poorly defined. The present study examined aspects of energy metabolism (body composition, feed intake, and metabolic hormones) in Merino sheep with high or low estimated breeding values for clean fleece weight (CFW) or fibre diameter (FD). The groups were selected to have similar mean liveweights. High CFW sheep had a lower proportion of fat (P < 0.01) and more lean tissue (P < 0.05) in their body, and ate more of a medium-quality diet (P < 0.05). Intake of a straw diet with low digestibility that imposed a physical constraint on feed intake was not associated with CFW. When fed at the same level (1.2 × calculated maintenance), high CFW sheep had lower plasma concentrations of glucose (P < 0.01), insulin (P < 0.05), and insulin-like growth factor-1 (P < 0.05), and higher concentrations of growth hormone (P < 0.001). Responses of plasma insulin or glucose to treatment with insulin, adrenaline, or propranolol were independent of CFW. No differences were found between the high and low FD groups, except that the plasma cortisol response to adrenocorticotrophic hormone (ACTH) was higher in sheep with low FD. Calculations indicate that the lower fat reserves and plasma insulin and glucose concentrations in the high CFW sheep are sufficient to account for previous reports of reduced number of lambs weaned in high CFW sheep. Furthermore, the results indicate that high CFW sheep have smaller metabolic energy reserves to withstand unfavourable feed conditions, and so may be less able to thrive and reproduce successfully in harsh feed environments.
Influence of whole wheat feeding on the development of gastrointestinal tract and performance of broiler chickens
Authors: Ravindran V. , Wu Y. B. , Thomas D. G. , Morel P. C. H.
Published: January 2006

The main aim of the present study was to investigate the changes in the relative growth of digestive organs of broilers as influenced by whole wheat feeding and age of birds. The secondary aim was to examine the effects of whole wheat feeding on broiler performance over a 5-week feeding period. Diets containing ground wheat and whole wheat (100 and 200 g/kg whole wheat replacing ground wheat during 1–21 days and 22–35 days, respectively) were placed in 4 replicate pens (46 birds/pen) each. Throughout the 5-week trial, the birds offered feed containing wheat as whole grain grew slower (P < 0.05) and consumed less (P < 0.05) feed than those offered feed containing ground wheat. Feed-to-gain ratio was not influenced (P > 0.05) by the form of wheat during the first 2 weeks, but was significantly lowered (P < 0.05) by whole wheat feeding from 3 weeks onwards. Over the 5-week period, the feed-to-gain ratio of birds fed the whole-wheat diet was 7 points better (P < 0.05) than of those fed the ground wheat diet. Improved feed efficiency from Week 3 onwards coincided with significant increases (P < 0.05) in the relative weights of the gizzard in birds fed the whole-wheat diet. Whole-wheat inclusion had no effect (P > 0.05) on the relative weights of crop, proventriculus, and pancreas or on the relative weight and length of the small intestine. The relative weights of storage sections of the gastrointestinal tract (crop, proventriculus, and gizzard) steadily declined during the 5-week period. The relative weights of pancreas and liver increased to Day 14 and decreased thereafter. The relative weights of intestinal segments were maximal during Weeks 1 and 2 of life, and declined rapidly with age. In general, the growth of different segments of the small intestine (duodenum, jejunum, and ileum) followed a similar pattern. The intestinal mass, measured as g tissue/cm tissue, steadily increased over the trial period, indicating that, although the relative size of the intestine declines with age, this decline is compensated by increased intestinal mass to support the nutrient supply function to the demand tissues.
Schizochytrium limacinum SR-21 as a source of docosahexaenoic acid: optimal growth and use as a dietary supplement for laying hens
Authors: Chin H. J. , Shen T. F. , Su H. P. , Ding S. T.
Published: January 2006

Culture conditions for the marine fungus Schizochytrium limacinum SR-21 (SR-21) to produce microbial docosahexaenoic acid (DHA) were evaluated, and the practicality of using this fungus product as a dietary supplement for laying Leghorn hens was investigated. The data showed that the cultured fungus produced high biomass and DHA. It generated 584 mg DHA/L of culture at the end of a 6-day culture. The fungus grew better at 25ºC than at 20ºC or 30ºC. With an increase in glucose concentration from 1% to 5% in the culture medium, biomass and DHA production were enhanced. A 6% glucose treatment reduced the biomass production compared with 5% glucose. A bioreactor was used to mass-produce SR-21. The biomass was increased from 1.12 g/L at Day 0 to 12 g/L at Day 4. We established optimal culture conditions of 5% glucose, 2% sea salt, and 1% yeast extract for SR-21. Three concentrations of dried fungal meal (0, 1, or 3% in the diet) were fed to birds over a 3-week period. There were no negative effects of 1 and 3% dietary SR-21 on egg production, egg weight, and egg yolk weight. The DHA content of yolk was increased by the dietary supplementation with the fungal meal both in the 1 and 3% treatments. Dietary fungal meal treatments increased the DHA concentrations of liver and plasma. However, dietary DHA enrichment had no effect on the expression of hepatic lipogenic genes in laying hens.
Variation in seed softening patterns and impact of seed production environment on hardseededness in early-maturing genotypes of subterranean clover
Authors: Norman H. C. , Smith F. P. , Nichols P. G. H. , Si P. , Galwey N. W.
Published: January 2006

This paper describes variation in the dynamics of seed softening (loss of impermeability) in 20 early-maturing genotypes, including 6 cultivars, of subterranean clover (Trifolium subterraneum L.). It reports the effect of 3 sites of seed production in south-western Australia on the pattern of softening in the first summer–autumn and on total softening over the subsequent 2 years. Seeds were softened at a single field location and in a diurnally fluctuating cabinet (60°C/15°C).
There was significant variation among genotypes in the pattern of seed softening over the first 5 months after senescence. Cultivars Nungarin, Dwalganup, and Geraldton softened most rapidly in late February, whereas cultivars Dalkeith, Urana, and Izmir softened most rapidly in late March. The duration of field exposure required in order for 50% of the first season’s softening to occur ranged from 44 to 108 days among the 20 genotypes. Persistence of hard seeds into the second and third years also varied among genotypes. Of the cultivars, Nungarin and Izmir had the highest levels of residual hard seed after 30 months (5.3% and 3.9%, respectively), whereas Dalkeith had the lowest (0.9%).
Site of seed production had a small but significant effect on both the pattern of softening in the first summer–autumn and the persistence of hard seeds in subsequent years. Seeds produced in a relatively high-rainfall site (768 mm of growing-season rainfall plus supplementary irrigation) had a slower rate of hard seed breakdown than those from either of 2 sites located in the wheatbelt (217 and 423 mm growing-season rainfall). Seed softening through exposure in the field and in a 60°C/15°C fluctuating-temperature cabinet was compared for all genotypes. The cabinet treatment was fairly successful in ranking genotypes for relative between-season hardseededness, although it underestimated total softening by an average of 16%. However, the cabinet treatment was a poor predictor of the within-season pattern of seed softening.
Late-season non-selective herbicide application reduces Lolium rigidum seed numbers, seed viability, and seedling fitness
Authors: Steadman Kathryn J. , Eaton Debra M. , Plummer Julie A. , Ferris David G , Powles Stephen B.
Published: January 2006

Experiments were conducted to investigate the effect of Lolium rigidum (annual ryegrass) seed developmental stage and application rate of glyphosate and SpraySeed (paraquat 135 g/L + diquat 115 g/L) on the number, germinability, and fitness of seeds produced. Glyphosate (450 g/L) was most effective when applied at a rate of 0.5–1 L/ha during heading and anthesis, reducing the number of filled seeds produced compared with unsprayed plants. Application post-anthesis, when seeds were at the milk to soft dough stage, was less effective. SpraySeed was most effective when applied post-anthesis, during the milk and early dough stages of seed development at a rate of 0.5–1 L/ha, resulting in the production of few viable seeds. Although some filled seeds were produced, most of the seeds were dead. Application during anthesis or once the seeds reached soft dough stage was less effective. For both herbicides, those seeds that were capable of germinating were smaller and had slower radicle and coleoptile growth, resulting in slower early seedling growth and reduced biomass production within the first month of growth. Additionally, glyphosate application reduced the proportion of seeds exhibiting dormancy. The anticipated reduction in seed competitive ability and altered emergence timing resulting from late-season herbicide application, even when application timing is not optimal, could be exploited to reduce the likelihood of successful L. rigidum establishment in the following season.
Hexose synthesis by cell wall invertase activity and its effects on the roasting behaviour of macadamia kernel
Authors: Albertson P. L. , Bursle J. K. , Forrester R. I. , McConchie C. A.
Published: January 2006

After roast darkening (ARD) is a defect concealed in the raw macadamia kernel, only becoming evident upon roasting. Kernels susceptible to some forms of ARD reportedly have a higher glucose and fructose concentration. By developing a procedure to simulate ARD and through the inclusion of effector molecules we have demonstrated that the enzyme invertase is key to this form of ARD. Biochemical analysis of raw mature kernel has shown high invertase activity. Separating the extract into pellet and soluble fractions showed that the high invertase activity occurred in the pellet fraction containing the cell wall isoform and that the soluble fraction had little activity. A broad peak in crude cell wall invertase activity occurred between pH 3.75 and 5.0. Enzyme kinetics of the cell wall invertase from crude extracts assayed at pH 4 indicated a high level of activity (Vmax = 4.11 ± 0.55 mg glucose produced/g fresh weight tissue.h), a high affinity for sucrose (Km = 2.02 ± 0.96 mm), and inhibition by MgCl2 (K
i
= 71.2 ± 12.5 mm). We propose that the initial step in the processes leading to ARD in macadamia could involve membrane damage and subsequent modification of the kernel sugar composition by cell wall invertase.
Minimising cold damage during reproductive development among temperate rice genotypes. I. Avoiding low temperature with the use of appropriate sowing time and photoperiod-sensitive varieties
Authors: Farrell T. C. , Fukai S. , Williams R. L.
Published: January 2006

Multiple-sown field trials in 4 consecutive years in the Riverina region of south-eastern Australia provided 24 different combinations of temperature and day length, which enabled the development of crop phenology models. A crop model was developed for 7 cultivars from diverse origins to identify if photoperiod sensitivity is involved in determining phenological development, and if that is advantageous in avoiding low-temperature damage. Cultivars that were mildly photoperiod-sensitive were identified from sowing to flowering and from panicle initiation to flowering. The crop models were run for 47 years of temperature data to quantify the risk of encountering low temperature during the critical young microspore stage for 5 different sowing dates. Cultivars that were mildly photoperiod-sensitive, such as Amaroo, had a reduced likelihood of encountering low temperature for a wider range of sowing dates compared with photoperiod-insensitive cultivars. The benefits of increased photoperiod sensitivity include greater sowing flexibility and reduced water use as growth duration is shortened when sowing is delayed. Determining the optimal sowing date also requires other considerations, e.g. the risk of cold damage at other sensitive stages such as flowering and the response of yield to a delay in flowering under non-limiting conditions. It was concluded that appropriate sowing time and the use of photoperiod-sensitive cultivars can be advantageous in the Riverina region in avoiding low temperature damage during reproductive development.
The response of sows to increased nutrient intake during mid to late gestation
Authors: King R. H. , Eason P. J. , Smits R. J. , Morley W. C. , Henman D. J.
Published: January 2006

Five hundred and ten multiparous sows were allocated at 66 days after mating to one of 6 dietary treatments that were imposed for the subsequent 35 days. The dietary treatments were 5 feeding levels of 2.2, 2.6, 3.0, 3.4, and 3.8 kg/day of a gestation diet containing 12.9 MJ DE/kg, 127 g crude protein/kg, and 5.6 g lysine/kg, plus a protein intake treatment where sows received 2.8 kg/day of a lactation diet containing 13.8 MJ DE/kg, 168 g crude protein/kg, and 8.3 g lysine/kg. After the treatment period, all sows were offered the lactation diet at the common feeding level of 3.0 kg/day and after farrowing, all sows were offered this diet ad libitum throughout lactation. Increasing feeding levels between Day 66 and Day 101 of pregnancy increased (P < 0.001) liveweight gain prior to farrowing but increased (P < 0.001) liveweight loss during lactation. The majority of the extra maternal energy intake during mid to late gestation was deposited as maternal gain. These linear weight responses during lactation were explained by the significant inverse relationship between voluntary daily feed intake in lactation (FI) and average daily digestible energy intake in the previous gestation (DE):

Neither increasing the feeding level during mid to late gestation nor increasing the protein content of the diet had any significant effect on litter birth weight, average piglet birth weight, or the standard deviation of individual piglet birth weight within the litter. In addition, there were no significant effects of gestation feeding treatments on litter size weaned or weaning weight. Furthermore, neither increasing the feeding level during mid to late gestation nor increasing the protein content of the gestation diet had any significant effect on subsequent fertility or litter size. In conclusion, when average individual piglet birth weight is already well in excess of 1.5 kg, there is no significant response to feed intake levels between 2.2 and 3.8 kg/day when offered between Day 66 and Day 101 of gestation.