bluuebunny/crossref_metadata_2025 huggingface dataset:
Residual stress in Si nanocrystals embedded in a SiO2 matrix
Authors: Arguirov T. , Mchedlidze T. , Kittler M. , Rölver R. , Berghoff B. , Först M. , Spangenberg B.
Published: August 2006

Multiple quantum wells consisting of alternating Si and SiO2 layers were studied by means of Raman scattering. The structures were fabricated by the remote plasma enhanced chemical vapor deposition of amorphous Si and SiO2 layers on quartz substrate. The structures were subjected to a rapid thermal annealing procedure for Si crystallization. The obtained results suggest that the Si layers consist of nanocrystals embedded in an amorphous Si phase. It was found that the silicon nanocrystals inside 2nm thin layers are under high residual compressive stress. Moreover, the metastable Si III phase was detected in these samples supporting the presence of large compressive stresses in the structures. The compressive stress could be relaxed upon local laser annealing.
Density functional theory study of deep traps in silicon nitride memories
Authors: Petersen Max , Roizin Yakov
Published: August 2006

Using density functional theory, the interaction of hydrogen with a nitrogen vacancy in β-Si3N4 is investigated. A single H atom was found to be energetically favorable over non- and doubly protonated vacancies. The traps composed of excess silicon and hydrogen have negative correlation energy which is connected with different distances of Si–H and Si–Si bonds in charged and neutral states. The energy gains after trapping are consistent with trap activation energies in advanced silicon nitride memories. Based on the present results, a model of memory traps is proposed.
High-performance ZnO∕ZnMgO field-effect transistors using a hetero-metal-insulator-semiconductor structure
Authors: Sasa Shigehiko , Ozaki Masashi , Koike Kazuto , Yano Mitsuaki , Inoue Masataka
Published: August 2006

The authors propose a new structure of ZnO∕ZnMgO field-effect transistors (FETs) for demonstrating high-performance capability of ZnO-based FETs. A very thin (2nm) ZnMgO cap layer is used for forming a hetero-metal-insulator-semiconductor (hetero-MIS) gate structure together with a 50-nm-thick Al2O3 gate dielectric. The 1-μm-gate device showed a complete FET operation and an extrinsic transconductance of as high as 28mS∕mm and an effective mobility of 62cm2∕Vs. The high effective mobility maintained down to such a short channel device is likely due to the use of the hetero-MIS structure, demonstrating the high-performance capability of ZnO-based FETs.
Efficient stimulated emission due to bimolecular annihilation reduction in oligothiophene dioxide thin films
Authors: Lattante S. , Barbarella G. , Favaretto L. , Gigli G. , Cingolani R. , Anni M.
Published: August 2006

We have studied the optical properties of a thienyl-S, S-dioxide oligothiophene under strong excitation. No stimulated emission is observed in neat films due to singlet-singlet bimolecular annihilation, with a bimolecular constant of A=(4.5±0.5)×10−11cm3s−1. On the contrary we show that strong stimulated emission is observed if the active molecule is blended to an inert polymer [poly(bisphenol A carbonate] (PC) even for a PC content as low as one PC molecule every 500 active molecules. We suggest that small PC quantities modify the film superamolecular packing, thus reducing the bimolecular recombination efficiency. These results are expected to be quite general and could allow a considerable extension of the number of molecules showing stimulated emission for organic laser applications.
Enhanced extraordinary magnetoresistance in the semiconductor-metal hybrid structure with three current leads
Authors: Rong Chuan-Bing , Zhang Hong-Wei , Sun Ji-Rong , Shen Bao-Gen
Published: August 2006

Earlier researches show that nonmagnetic semiconductor-metal hybrid structures exhibit a very large magnetoresistance effect, the so-called extraordinary magnetoresistance effect. Here, we designed a modified semiconductor-metal hybrid device with IVIVI configuration, where I and V represent current lead and voltage probe, respectively. In this device, applied magnetic field can lead to the current redistribution between the two output current leads. The change of the output currents reaches 62.4% under magnetic field of 5T. As a result, the magnetoresistance value is 2.4–3.7 times higher than that of the traditional semiconductor-metal hybrid device with IVVI configuration. The sensitive position dependence of magnetic bit on output current shows that this device could be potentially used as magnetic sensor.
Lasing in high-Q quantum-dot micropillar cavities
Authors: Reitzenstein S. , Bazhenov A. , Gorbunov A. , Hofmann C. , Münch S. , Löffler A. , Kamp M. , Reithmaier J. P. , Kulakovskii V. D. , Forchel A.
Published: August 2006

We present lasing in optically pumped high-Q micropillar cavity lasers with low thresholds and high β factors. The micropillar cavities with diameters between 1.0 and 4.0μm contain a single layer of low density In0.3Ga0.7As quantum dots as active region. Cavity Q factors of up to 23.000 for 4.0μm micropillar cavities and lasing based on less than 70 quantum dots is demonstrated.
Gating of an organic transistor through a bilayer lipid membrane with ion channels
Authors: Bernards Daniel A. , Malliaras George G. , Toombes Gilman E. S. , Gruner Sol M.
Published: August 2006

The authors use bilayer lipid membranes (BLMs) as a means to control the gating of organic electrochemical transistors (OECTs). Upon formation of a high quality BLM, the gating of an OECT can be fully suppressed. Gating is restored when gramicidin ion channels are incorporated into the BLM. The valence-dependent permeability of gramicidin enables these devices to discriminate between monovalent and divalent ions. This work shows that ion channels can be effectively employed to control the selectivity of organic transistor-based sensors.
Optical gain and lasing of ZnO∕ZnMgO multiple quantum wells: From low to room temperature
Authors: Cui Jian , Sadofev S. , Blumstengel S. , Puls J. , Henneberger F.
Published: August 2006

Optical gain and lasing properties of ZnO∕ZnMgO multiple quantum wells with and without separate optical confinement are investigated in the temperature range from 5to290K. The data signify that localized states are crucially involved in the laser action up to room temperature. The lasing threshold increases by about one order of magnitude and reaches 140kW∕cm2 at 290K. The room temperature material gain is in the 103cm−1 range.
Separation of colloidal nanoparticles using capillary immersion forces
Authors: Gordon Michael J. , Peyrade David
Published: August 2006

Capillary force assembly (CFA) of colloidal particles usually results in closed-packed films or particle aggregation within topographic features. In this work, it is shown that CFA can also be exploited to both localize and separate nanoparticles (d=50–200nm) when template shape and wettability are controlled. Well-defined geometric arrangements of one to four closely spaced particles (30–50nm separation) were realized in large arrays using this technique to demonstrate that particle aggregation during dewetting can be eliminated. Ordered SiO2 nanopillars in tight groupings were obtained by combining low-resolution e-beam lithography (>100nm) with CFA and etching. This approach provides a simple route to fast and precise placement of nanostructures using relatively low-resolution pattern making techniques.
Low-temperature photoluminescence imaging and time-resolved spectroscopy of single CdS nanowires
Authors: Titova L. V. , Hoang Thang Ba , Jackson H. E. , Smith L. M. , Yarrison-Rice J. M. , Lensch J. L. , Lauhon L. J.
Published: August 2006

Time-resolved photoluminescence (PL) and micro-PL imaging were used to study single CdS nanowires at 10K. The low-temperature PL of all CdS nanowires exhibits spectral features near energies associated with free and bound exciton transitions, with the transition energies and emission intensities varying along the length of the nanowire. In addition, several nanowires show spatially localized PL at lower energies which are associated with morphological irregularities in the nanowires. Time-resolved PL measurements indicate that exciton recombination in all CdS nanowires is dominated by nonradiative recombination at the surface of the nanowires.
Organic oxide/Al composite cathode in small molecular organic light-emitting diodes
Authors: Guo Tzung-Fang , Yang Fuh-Shun , Tsai Zen-Jay , Wen Ten-Chin , Wu Ching-In , Chung Chia-Tin
Published: August 2006

This study addresses the feasibility of using an organic oxide/Al composite cathode to fabricate the small molecular organic light-emitting diodes (OLEDs). A supplementary organic buffer film is placed at the interface between the tris(8-hydroxyquinoline) aluminum (Alq3) and the organic oxide/Al complex layers. Incorporating the rubrene/poly(ethylene glycol) dimethyl ether (PEGDE) buffer layers into the composite cathode structure markedly improves the performance of devices. The luminous efficiencies of Alq3-based OLEDs biased at ∼100mA∕cm2 are 4.8 and 5.1cd∕A for rubrene (50Å)/PEGDE (15Å)∕Al and rubrene (50Å)/PEGDE (15Å)∕LiF (5Å)∕Al cathode devices, and 1.3 and 3.8cd∕A for devices with Al and LiF (5Å)∕Al cathodes, respectively.
Variation of output properties of perylene field-effect transistors by work function of source/drain electrodes
Authors: Ohta Toshio , Nagano Takayuki , Ochi Kenji , Kubozono Yoshihiro , Shikoh Eiji , Fujiwara Akihiko
Published: August 2006

Field-effect transistor (FET) devices with thin films of perylene have been fabricated with various metal electrodes exhibiting work function ϕ from 2.5to5.1eV. All perylene FET devices show p-channel FET properties. The p-channel field-effect mobility μp and the on-off ratio in the perylene FET increase with an increase in ϕ of the metal electrodes. The n-channel conduction is also observed for the FET devices with Eu and Sr electrodes exhibiting small ϕ. These results can be reasonably explained on the basis of energy barrier for hole or electron.
Inhomogeneous transport properties in phase-separated manganite thin films
Authors: Munakata Ko , Takubo Naoko , Tamaru Hiroharu , Miyano Kenjiro
Published: August 2006

Pronounced inhomogeneity in resistance was detected in Pr0.55(Ca1−ySry)0.45MnO3 thin films by adopting a small contact probe. A large-scale phase separation has been demonstrated consisting of insulating and metallic domains, which can be manipulated by applying large voltage. The extent of the phase separation critically depends on the composition, temperature, and thermal history.
Ultraviolet irradiation-induced photoluminescence degradation in γ-alumina nanoparticles
Authors: Liu Sufeng , Zhang Ligong , Fan Yi , Luo Jinsong , Zhang Peiping , An Linan
Published: August 2006

The photoluminescence (PL) behavior of γ-Al2O3 nanopowder is studied. Two emission peaks at 343 and 378nm and a broadband ranging between 400 and 600nm are observed. The peaks are attributed to F+ center, while the broadband is attributed to impurities. It is found that irradiating the sample with intense ultraviolet (UV) light can cause significant decrease in the intensity of the two peaks, but has no effect on the broadband. A simple model is proposed to explain the kinetics of UV irradiation-induced PL degradation.
Solution-processed pentacene quantum-dot polymeric nanocomposite for infrared photodetection
Authors: Roy Choudhury Kaushik , Kim Won Jin , Sahoo Yudhisthira , Lee Kwang-Sup , Prasad Paras N.
Published: August 2006

An organic/inorganic polymeric nanocomposite thin film device, consisting of poly-N-vinyl carbazole as host matrix, lead selenide quantum dots as photosensitizer, and the organic semiconductor pentacene as a conductivity booster, is fabricated. Because of the inherent insolubility of pentacene, it is incorporated in the form of a soluble precursor which is made to undergo thermal conversion into pentacene. The device exhibits dramatic enhancement of infrared photocurrent due to pentacene. Efficient photogeneration of carriers coupled with enhanced conductance results in high photoconductive quantum efficiency.
Energy distribution of O− ions during reactive magnetron sputtering
Authors: Mráz Stanislav , Schneider Jochen M.
Published: August 2006

Low, medium, and high energy O− ion populations were experimentally detected during magnetron sputtering of Al in an Ar∕O2 atmosphere. Based on calculations, the authors propose that nonsputtered O− ions originating from the target surface are accelerated in the cathode fall, while sputtered O− ions may be excluded as a significant contribution to the high energy ion population. Furthermore, the formation of medium energy O− ions is consistent with the notion of sputtered, in the cathode fall accelerated, and subsequently dissociated AlO− and AlO2− clusters. These findings may be of importance for understanding plasma energetics and growth involving electronegative species.
Depth resolution improvement in secondary ion mass spectrometry analysis using metal cluster complex ion bombardment
Authors: Tomita M. , Kinno T. , Koike M. , Tanaka H. , Takeno S. , Fujiwara Y. , Kondou K. , Teranishi Y. , Nonaka H. , Fujimoto T. , Kurokawa A. , Ichimura S.
Published: August 2006

Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir4(CO)7+ as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of ∼1nm under 5keV, 45° condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5keV with higher incident angles.
Anomalous polarized absorbance spectra of aligned Ag nanorod arrays
Authors: Chaney S. B. , Zhang Z.-Y. , Zhao Y.-P.
Published: August 2006

The polarized absorbance spectra of Ag nanorod array substrates with different lengths prepared by oblique angle deposition were studied in detail. An anomalous anisotropic absorbance was obtained which follows the relation α(θ)=−ln[A(1+Bsin2θ)]β, where θ is the polarization angle with respect to p-polarization direction. The exponent β(<0.5) is wavelength independent. This result cannot be interpreted by the conventional anisotropic effective medium theory, and the possible origin is the inhomogeneous size and orientation distributions that cause the variations in transmission and polarization.
H
2
cold plasma on Pd∕H system at low hydrogen pressure
Authors: Baldi A. , Di Pascasio F. , Gozzi D.
Published: August 2006

The effect of hydrogen cold plasmas, in negative corona regime, was investigated on the palladium-hydrogen system in the α+β region at room temperature and H2 pressures below 0.037bar. Three independent experimental quantities have been simultaneously measured: hydrogen concentration, electrical resistance, and elongation of the samples. An increase in the above quantities was always observed when plasma was lighted. The ability of an external electric field (the corona discharge) to perturb the thermodynamic state of the Pd∕H system was experimentally demonstrated.
Drift mobility of long-living excitons in coupled GaAs quantum wells
Authors: Gärtner A. , Holleitner A. W. , Kotthaus J. P. , Schuh D.
Published: August 2006

The authors report on high-mobility transport of indirect excitons in coupled GaAs quantum wells. A voltage-tunable in-plane potential gradient is defined for excitons by exploiting the quantum confined Stark effect in combination with a lithographically designed resistive top gate. Excitonic photoluminescence resolved in space, energy, and time provides insight into the in-plane drift dynamics. Across several hundreds of microns an excitonic mobility of 105cm2∕eVs is observed for temperatures below 10K. With increasing temperature the excitonic mobility decreases due to exciton-phonon scattering.
High quality silicon-germanium-on-insulator wafers fabricated using cyclical thermal oxidation and annealing
Authors: Wang Grace Huiqi , Toh Eng-Huat , Foo Yong-Lim , Tung Chih-Hang , Choy Siew-Fong , Samudra Ganesh , Yeo Yee-Chia
Published: August 2006

An improved fabrication scheme for forming strained SiGe on insulator (SGOI) is demonstrated. Cyclical thermal oxidation and annealing (CTOA) process is introduced to mitigate issues associated with surface roughening and nonuniformity due to increased germanium (Ge) content during SiGe oxidation. Annealing in an inert ambient can be introduced between each oxidation phase to homogenize the Ge content. The root-mean-square surface roughness of the SGOI layer is evaluated to be 0.41nm. With CTOA, a high quality SGOI substrate is obtained. This technique is promising for the fabrication of dislocation-free SGOI layers for applications in high mobility metal-oxide-semiconductor field-effect transistors.
Field effect luminescence from Si nanocrystals obtained by plasma-enhanced chemical vapor deposition
Authors: Perálvarez M. , García C. , López M. , Garrido B. , Barreto J. , Domínguez C. , Rodríguez J. A.
Published: August 2006

Field effect induced luminescence has been achieved by alternate tunnel injection of electrons and holes into Si nanocrystals. The emitting device is a metal-oxide-semiconductor structure with a semitransparent polycrystalline Si contact ∼250nm thick and a silicon-rich silicon oxide layer of about 40nm deposited on a p-type Si substrate by plasma-enhanced chemical vapor deposition. The electroluminescence is optimized for a Si excess of 17% and annealing at 1250°C for 1h in nitrogen-rich atmosphere. The pulsed emission presents typical decay times of ∼5μs and external quantum efficiencies of ∼0.03%.
Highly efficient and stable inverted bottom-emission organic light emitting devices
Authors: Chu Ta-Ya , Chen Jenn-Fang , Chen Szu-Yi , Chen Chao-Jung , Chen Chin H.
Published: August 2006

The authors report the development of highly efficient and stable C545T doped green fluorescent Alq3 inverted bottom-emission organic light emitting device (OLED), with a device configuration of ITO∕Mg∕Cs2O:Bphen∕Alq3∕C545T:Alq3∕NPB∕WO3∕Al, that achieved a maximum current efficiency of 23.7cd∕A and a power efficiency of 12.4lm∕W which are two times better than those of the conventional OLED. At a brightness level of 100cd∕m2, the device required driving current density only as low as 0.5mA∕cm2 at a driving voltage of only 5.0V and its half-lifetime T1∕2 in excess of 104000h.
Prestrained effect on the emission properties of InGaN∕GaN quantum-well structures
Authors: Huang Chi-Feng , Tang Tsung-Yi , Huang Jeng-Jie , Shiao Wen-Yu , Yang C. C. , Hsu Chih-Wei , Chen L. C.
Published: August 2006

The authors demonstrate the spectral redshift of the quantum wells (QWs) designated for green emission into the orange range in a light-emitting diode by adding a violet-emitting QW at the bottom in metal-organic chemical vapor deposition. An electroluminescence redshift of 53nm was obtained. The cathodoluminescence spectra indicated that the long-wavelength QWs close to the violet one were strongly influenced by this added QW and mainly emitted the orange photons. Those near the top were less affected. This influence is supposed to originate from the prestrained effect in the barrier layer right above the violet QW. Such a prestrained effect is expected to be more effective when the underlying QW is well shaped and the heterojunction strain is strong, like the case of the violet QW. This effect is weak between the high-indium QWs, in which the formation of indium-rich clusters releases the strain.
Manipulation of ferrofluid droplets using planar coils
Authors: Nguyen Nam-Trung , Ng Kon Meng , Huang Xiaoyang
Published: August 2006

In this letter, the authors report a system for magnetic manipulation of ferrofluid droplets and their dynamic behavior. The magnetic field was generated by an array of planar coils, which were fabricated on a double-sided printed circuit board (PCB). The permanent magnetic moment of the ferrofluid droplet was created by the field of a pair of permanent magnets. The motion of the ferrofluid droplet is further aligned in a virtual channel formed by a pair of planar coils. Two other planar coils on the other side of the PCB drive the droplet along this virtual channel. The direction of the droplet motion can be controlled by reversing the electric current in the coils. Based on the experimental results, a larger droplet size, a lower viscosity of the surrounding medium, and a higher electric current will increase the droplet velocity.
From zero resistance states to absolute negative conductivity in microwave irradiated two-dimensional electron systems
Authors: Iñarrea J. , Platero G.
Published: August 2006

Recent experimental results regarding a two-dimensional electron gas subjected to microwave radiation reveal that magnetoresistivity, apart from presenting oscillations and zero resistance states, can evolve to negative values at minima. Here the authors present a theoretical model which explains the transition from zero resistance states to absolute negative conductivity in terms of multiphoton assisted electron scattering due to charged impurities and shows how this transition can be driven by tuning microwave frequency and intensity. This opens the possibility of controlling the magnetoconductivity in microwave driven nanodevices and understanding the novel optical and transport properties of such devices.
Highly efficient epitaxial Bragg mirrors with broad omnidirectional reflectance bands in the midinfrared
Authors: Baumgartner E. W. , Schwarzl T. , Springholz G. , Heiss W.
Published: August 2006

Laser-quality low-loss epitaxial Bragg mirrors exhibiting a broad omnidirectional stop band in the midinfrared at wavelengths around 7μm are presented. The mirror layers, composed of PbTe and EuTe, exhibit a high refractive index contrast of 80%. Thus, with only three layer pairs, reflectances higher than 99% are achieved for angles of incidence up to 40° and higher than 98% for angles of incidence up to 60°. The angle dependence of the reflectance is accurately determined by analyzing the width of the cavity resonance in a half-wavelength microcavity, formed by two such Bragg mirrors. The experimentally determined omnidirectional stop bandwidth is as high as 50% of the target wavelength. The results are in good agreement to analytical calculations based on the transfer matrix method.
Tunable resonance in surface-plasmon-polariton enhanced spontaneous emission using a denser dielectric cladding
Authors: Chen Jing , Shen Nian-Hai , Cheng Chen , Fan Ya-Xian , Ding Jianping , Wang Hui-Tian
Published: August 2006

The authors propose an approach in tuning the resonance energy of spontaneous emission mediated by surface plasmon polariton, using a stratified structure of dielectric (D0)-metal (M)-dielectric (D1)-dielectric (D2). When the dielectric constants satisfy the condition of εD1>εD0>εD2 or εD1<εD0<εD2, the resonance can be tuned by changing the thickness of D1 layer. A configuration of GaN–Ag–Si–air is utilized to prove the feasibility of our approach, in which the silicon cladding is optically denser than GaN. This configuration is much simpler than those schemes proposed before and should be easily demonstrated by experiment.
Tuning the magnetic anisotropy of ultrathin Fe∕Ag(001) films from biaxial to uniaxial by ion sculpting
Authors: Bisio F. , Moroni R. , Buatier de Mongeot F. , Canepa M. , Mattera L.
Published: August 2006

Ion sculpting of ultrathin Fe∕Ag(001) films induces the self-assembled formation of nanometric surface ripples oriented along the ion beam direction and the corresponding onset of an in-plane uniaxial contribution to magnetic anisotropy. The authors show that fine tuning of the ion dose impinging on the film allows to tailor the in-plane magnetic anisotropy of such films from purely biaxial in the as-grown state to purely uniaxial. The magnitude of magnetic anisotropy in the pure uniaxial state can be tailored by varying the Fe film thickness prior to irradiation.
Direct observation of half-metallic energy gap in Co2MnSi by tunneling conductance spectroscopy
Authors: Sakuraba Y. , Miyakoshi T. , Oogane M. , Ando Y. , Sakuma A. , Miyazaki T. , Kubota H.
Published: August 2006

Magnetic tunnel junctions with a Co2MnSi∕Al–O∕CoFe structure are prepared by magnetron sputtering and investigated with respect to the energy gap near the Fermi energy level. The plasma oxidation time for the Al–O barrier is found to affect the condition of the Co2MnSi∕Al–O interface. The optimized sample (50s oxidation time) exhibits a magnetoresistance ratio of 159% and tunneling spin polarization of 0.89 at 2K. The bias voltage dependence of tunneling conductance (dI∕dV−V) reveals a clear half-metallic energy gap at 350–400meV for Co2MnSi, with an energy separation of just 10meV between the Fermi energy and the bottom edge of conduction band.
Dielectric discontinuity at structural boundaries in Si
Authors: Nakamura Jun , Natori Akiko
Published: August 2006

The authors have explored optical dielectric constants, ε∞, of ultrathin 3C(diamond)-Si(111) and 2H(wurtzite)-Si(0001) films using first-principles calculations in finite external electric fields. ε∞ evaluated at the innermost region of the films approach values near their bulk dielectric constants at a thickness of only eight bilayers: 12.8 (3C) and 13.4 (2H). Furthermore, the authors have revealed that the spatial variation of ε∞ near the stacking fault corresponding to the twin boundary for3C-Si and that at the heteroboundary between 3C- and 2H-Si changes abruptly at the boundary for both cases. Such a locality in the variation of ε∞ originates from the local atomic arrangement at the boundary.
Linear to axial or radial polarization conversion using a liquid crystal gel
Authors: Ren Hongwen , Lin Yi-Hsin , Wu Shin-Tson
Published: August 2006

Two types of liquid crystal (LC) gels with radial or twisted-radial molecular orientation are fabricated using a radial electric field generated by an indium-tin-oxide hole electrode in the bottom substrate. If the top substrate is not buffed, the radial-type LC gel is formed which can convert linearly polarized light into axially polarized light. On the other hand, if the top substrate is homogeneously buffed, then a twisted-radial LC gel is produced which can convert linearly polarized light into radially polarized light. These polarization converters are useful for diffractive optics and optical imaging systems.
Fluorine-vacancy complexes in ultrashallow B-implanted Si
Authors: Abdulmalik D. A. , Coleman P. G. , Cowern N. E. B. , Smith A. J. , Sealy B. J. , Lerch W. , Paul S. , Cristiano F.
Published: August 2006

Shallow fluorine-vacancy (FV) complexes in Si have been directly observed using variable-energy positron annihilation spectroscopy and secondary ion mass spectrometry. The FV complexes, introduced to combat the deactivation and transient-enhanced diffusion of ultrashallow boron, were observed in preamorphized Si wafers implanted with 0.5keV B and 10keV F ions at a dose of 1015cm−2, and then annealed isothermally at 800°C for times ranging from 1to2700s. The results are in agreement with a model which predicts that the complexes are of the form F3nVn, with n most probably being 1 and/or 2.
Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers composite film electrodes
Authors: Wang X. Z. , Li M. G. , Chen Y. W. , Cheng R. M. , Huang S. M. , Pan L. K. , Sun Z.
Published: August 2006

Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers (CNTs-CNFs) composite film electrodes has been demonstrated. The large area CNTs-CNFs film was directly grown on Ni plate by low pressure and low temperature thermal chemical vapor deposition. The CNTs-CNFs electrodes have great advantages such as low cost, easy operation, long-term reproducibility, and integrity of monolithic CNTs-CNFs film and current collector. Batch-mode experiments at low voltage (0.4–2V) were conducted in a continuously recycling system to investigate the electrosorption process. Purification of water with good reproducibility was achieved because of optimal pore size distribution of CNTs-CNFs composite films.
Self-organization in electron temperature gradient driven turbulence
Authors: Idomura Y.
Published: August 2006

Based on first principle gyrokinetic calculations, a zonal flow generation mechanism in the slab electron temperature gradient driven (ETG) turbulence with weak magnetic shear is identified as self-organization via the turbulent spectral cascade in the two dimensional rotating fluid turbulence. The inverse energy cascade and the scaling of a zonal flow wavenumber, which is consistent with the Rhines scale length, are confirmed. An impact of the scaling, which depends on the density gradient, on the turbulent structure and transport is demonstrated for the slab ETG turbulence.
Burning Cities: A Posthumanist Account of Australians and Eucalypts
Authors: Franklin Adrian
Published: August 2006

In this paper I want to ask whether there is anything to be gained by taking seriously a posthumanist analysis of the relationship between humanity and the natural world, one that in fact extinguishes the dualism and produces only ‘naturecultures’. I will examine this question through a new analysis of the relationship between gum trees and Australia. Most humanist accounts, such as those developed in ‘traditional’ social anthropology and sociology, privilege the activity, agency, and representations of humans, and in so doing render the natural world and its individual species as passive and of interest only insofar as they provide a palette of meanings for essentially human symbolism, dreamings, and imaginaries. Such an approach has an impeccable track record from Emile Durkheim to Mary Douglas and it is not one I want to challenge here per se. What I do want to challenge is the implicit assumption that this is all there is to, or all we can say about, the relationship between nature and humanity. Rather than (only) ask what nature (or gum trees in this case) means, I want to ask (also) what nature does, and, importantly, what implications those actions have for the world, nature, humans, and ‘the social’. I argue that this approach takes us considerably further towards a more mature sociology of nature in Australia.
Depths and Folds: On Landscape and the Gazing Subject
Authors: Wylie John
Published: August 2006

The aim of this paper is to take some steps towards a renewed understanding of landscape and the gazing subject. A first main section, ‘Depth, outlines Merleau-Ponty's final visual philosophy and its attempts to replace a spectatorial conception of vision with an embodied ontology that accords transcendance to the depth of the visual world. A second section, ‘fold’, engages with Deleuze's rendition of Leibniz's philosophy as a means of both critiquing and supplementing Merleau-Ponty's account. Through these analyses I seek to rewrite the visual gaze upon landscape by exploring the ontological processes (processes of depth, processes of folding) which afford its actualisation. I thus seek to produce an account of gazing as an eventful actualisation and distribution of selves and landscape, through attending to the depths and folds of an immanent plane, from which distinctive and durable selves and landscapes arise and with which they are always in relation. Here, landscape is not a way of seeing the world. Nor is it ‘something seen’, an external, inert surface. Rather, the term ‘landscape’ names the materialities and sensibilities with which we see.
Herding Memories of Humans and Animals
Authors: Lorimer Hayden
Published: August 2006

The study of a herd marks the point where ethnography and ethology meet. In the midst of this shared phenomenon, versions of ‘the social’ hinge on relations between herders and herd. In this paper I consider how our understanding of a herd might be extended by an awareness of its diverse geographies. This is achieved by reconstructing the entwined biographies of human and animal subjects dating from the reintroduction of reindeer to Scotland in 1952. The first transportation of reindeer from Scandinavia to the Cairngorm mountains was orchestrated by Mikel Utsi, a Lappish emigré from northernmost Sweden, and Ethel John Lindgren, a social anthropologist from Cambridge, of American–Swedish descent. What began as an ecological–economic experiment would occupy the couple until their deaths: Utsi's in 1979 and Lindgren's in 1988. I draw on a ‘make-do’ methodology undertaken in collaboration with past herders and the scattered company of the present herd: walking a sentient topography of traditional grazing grounds; renewing encounters with charismatic animals through photographic portraits; consulting an archive of herding diaries; and mapping a hidden ecology of landscape relics. These different registers of memory are used to explore how day-to-day engagements between herders and herd were rooted in unconventional systems of ecological and cultural knowledge. By reanimating a local landscape, the resulting narrative works at an intimate scale, while simultaneously gathering momentum from transnational movements of humans, animals, and traditions. Here, salvage and exchange are possible between geography's heritage of landscape and folk study and the sculpting of contemporary research.
Rethinking Landscape and Colonialism in the Context of Early Spanish Peru
Authors: Scott Heidi V
Published: August 2006

Efforts to work towards the rematerialisation of landscape have recently been augmented by concerns for corporeal, nonrepresentational dimensions of landscape experience as well as for nonhuman agency. Increasingly, landscape is conceptualised as a never-finished product of processes and practices that are both material and symbolic. Although such trends are reflected to some extent in work on landscape in colonial contexts, in this paper I contend that a closer engagement with these new directions may offer a useful means of breathing new life into colonial landscapes that, in some scholarly work, appear to have little existence beyond European representations that were made of them. Arguing for a conception of colonial landscape as process, I suggest that there is a need not only for recognising the material and corporeal dimensions of European experiences of colonial landscapes but also for attending to the ways in which those landscapes were brought into being and given meaning through the frequently mundane and locally focused activities of everyday life. Following a brief review of recent work on colonial landscapes, these suggestions are explored in the context of Spanish encounters with landscape in early colonial Peru. Initially focusing on accounts produced between the eve of conquest and the mid-16th century, the analysis then shifts to a legal battle that was fought in the early 17th century between two priests who occupied neighbouring parishes in the highland province of Huarochirí.
The Accomplishment of Spatial Adequacy: Analysing CCTV Accounts of British Town Centres
Authors: Neyland Daniel
Published: August 2006

The number of closed-circuit television (CCTV) cameras in British town centres has rapidly increased in recent years. These increases are mirrored in Europe and North America. In Britain many of these cameras videotape town centres, 24 hours a day, 365 days a year. How do CCTV systems account for the space of the town centres in which they operate? What theoretical sensibilities can we use to engage with CCTV spatial accounting? To what extent do terms such as ‘professional,’ ‘legal’, ‘sociotechnical’, and ‘mundane’ enable adequate renditions of spatial-accounting activity? In this paper I will argue that engagement with the accomplishment of mundane public flows and specific incidents of accountable otherness can initiate a discussion of these questions and initiate an alternative to panoptic renditions of CCTV. The discussion will seek to draw together a potentially tense and disruptive theoretical combination of ethnomethodology and science and technology studies.
Advertising and the Metabolism of the City: Urban Space, Commodity Rhythms
Authors: Cronin Anne M
Published: August 2006

In this paper I explore the role of outdoor advertising in organising city space and framing people's experience of that space. I examine how UK outdoor advertising companies remap that space, segmenting and pricing certain areas of cities, and routes to and around cities. I argue that, in this cartographic, taxonomising role, advertising constitutes one of the forces that continually makes and remakes city space. Using Lefebvre's concept of city rhythms, I argue that outdoor advertising acts to align the urban rhythms of travel and work with the commercial rhythms of product innovation, promotion, and the life cycle of the commodity. This creates an urban time–space of ‘commodity rhythms’ which has important implications for people's experience of cities whilst engendering new connections between commodities and people moving around cities. I argue that this constitutes an adaptation of Foucault's biopolitics where it is precisely the rhythmic connections between populations of people and populations (and life cycles) of commodities that are at stake: it is a mutation of the metabolism of city spaces.
Gathering ‘Dreams of Presence’: A Project for the Cultural Landscape
Authors: Rose Mitch
Published: August 2006

In accepting an ontology that takes imminence and becoming as given and subverts any gestures towards ossifying movement into coherencies such as culture, it is difficult to explain how certain kinds of subject–object relationships, such as the cultural landscape, present themselves to us as stable and a-contextually fixed. How might such apparent coherencies be accounted for? The question calls for a shift not only in what we mean by representation but, more importantly, in how we ‘take’ representation—that is, how we engage, interact, or acknowledge the presentation of a stable, demobilised, and closed world. I argue that this shift can take place only if landscape studies jettisons its reliance on concepts such as culture to explain the presence of the landscape and begins to think about such coherencies as a performance of coherence rather than coherence itself. I draw upon Derrida's idea of ‘dreams of presence’ to describe these performances of coherence as well as to theorise more broadly how an always-already deconstructing world can often be presented to us as closed.
“'S Leinn Fhèin Am Fearann” (The Land is Ours): Re-Claiming Land, Re-Creating Community, North Harris, Outer Hebrides, Scotland
Authors: Fiona A , Mackenzie D
Published: August 2006

This paper tells a story of the community's purchase of the North Harris Estate, Isle of Harris, Scotland, bringing the land under collective ownership where previously it was held by an individual as a ‘private’ estate. At the broadest level the paper contributes conceptually to research whose objective is to challenge the inevitability of global imaginaries. Situated in the specific context of the Land Reform (Scotland) Act 2003, such action as that of the North Harris Trust has the potential to disturb global narratives of enclosure and privatisation. In recounting the story, the argument centres on the political possibilities of the land. In parallel with arguments concerning ‘place’, I examine how the re-creation of a collective, place-based identity in the new political spaces afforded by the North Harris Trust is linked to the process of negotiating the meanings of the land. The meanings of the land relate both to the mediation of historically resonant collective rights to the land and to how ‘nature’ is constituted in the search for socially just and sustainable futures. The focus is on the principles and everyday practices through which land and community are coproduced.
Comparative responses of Lolium perenne and Phalaris aquatica to multiple growth stresses
Authors: Cullen B. R. , Chapman D. F. , Quigley P. E.
Published: August 2006

The growth and carbon distribution patterns of perennial ryegrass (Lolium perenne L. cv. Yatsyn1) and phalaris (Phalaris aquatica L. cv. Holdfast) were analysed in response to defoliation and limited nitrogen availability stresses, imposed both individually and in combination. Both species showed similar responses to defoliation and nitrogen limitation when applied individually. Defoliation increased proportional export of carbon from residual leaves and carbon distribution to tillers was increased at the expense of roots. Nitrogen deficiency resulted in increased export of carbon to the root system. These results are consistent with source–sink theory. A key finding from this study was that the species responded differently when defoliation and nitrogen limitation were imposed simultaneously. Under these conditions, carbon distribution patterns in phalaris resembled those seen in plants subjected to nitrogen stress, that is, favouring root growth. The response of perennial ryegrass was to continue to support shoot growth at the expense of roots. These results suggest a physiological basis for the poor survival of perennial ryegrass often observed under continuous grazing in dry regions of southern Australia. Results are discussed in relation to the environments to which each species is adapted, and the management requirements for species persistence in marginal environments.
The hydrology of Vertosols used for cotton production: II. Pedotransfer functions to predict hydraulic properties
Authors: Vervoort R. W. , Minasny B. , Cattle S. R.
Published: August 2006

Using a range of earlier published results and a recently published dataset, pedotransfer functions (PTFs) were developed to predict some hydraulic properties of Vertosols. A fitting approach using neural networks was employed with good results to predict the soil water characteristic curve. The developed functions are complex due to the large numbers of parameters, but moisture contents are predicted to within 5%. Other PTFs to predict the moisture content at the drained upper limit (DUL) and lower limit (LL), and bulk density in the normal shrinkage curve, were developed using multiple linear regression. The PTFs to predict the soil water characteristic curve, DUL and LL, and the bulk density in the normal shrinkage zone were mainly based on total clay, sand, and silt contents and bulk density, with minor contributions of ECEC and total carbon content. PTFs for unsaturated hydraulic conductivities were also developed using multi-linear regression and were mainly dependent on silt contents and ESP values. The mean error in these predictions was 2.76 mm/h, which is reasonable for predictions at the field and farm scale where inherent soil variability can cause larger variation. The developed PTFs can be used to predict parameters needed in crop modelling tools such as OZCOT to simulate cotton development on Vertosols. Some further examples of the use of the PTFs for management of irrigation are given.
Long-term continuous cropping, fertilisation, and manuring effects on physical properties and organic carbon content of a sandy loam soil
Authors: Hati K. M. , Swarup A. , Singh D. , Misra A. K. , Ghosh P. K.
Published: August 2006

Effects of continuous cropping, fertilisation, and manuring on soil organic carbon content and physical properties such as particle size distribution, bulk density, aggregation, porosity, and water retention characteristics of a Typic Ustochrept were examined after 31 cycles of maize–wheat–cowpea (fodder) crop rotation. Five contrasting nutrient treatments from a long-term fertiliser experiment were chosen for this study: control (no fertiliser or manure); 100% (optimum dose) nitrogen (N) fertiliser; 100% nitrogen and phosphorus (NP); 100% nitrogen, phosphorus, and potassium (NPK); 100% NPK + farmyard manure (NPK+FYM). The NPK+FYM treatment significantly improved soil organic carbon (SOC) content in 0–0.15 m soil compared with the other 4 treatments; the NPK treatment resulted in significantly more SOC than the control and N treatments (P < 0.05). The SOC in NPK and NPK+FYM treatments was 38.6 and 63.6%, respectively, more than the initial level of SOC (4.4 g/kg) after 31 cycles of cropping. The control and N treatments maintained the SOC status of the soil at the initial value. NPK+FYM significantly improved soil aggregation, soil water retention, microporosity, and available water capacity and reduced bulk density of the soil at 0–0.30 m depth. Greater crop growth under the NPK treatment resulted in increased organic matter content of soil, which improved aggregate stability, water retention capacity, and microporosity compared with the control. The effects were more conspicuous with the NPK+FYM treatment and at the surface soil (0–0.15 m). Application of imbalanced inorganic fertiliser (N and NP treatments) did not have a deleterious effect on the physical properties of the soil compared with the control. SOC content showed a highly significant and positive correlation with mean weight diameter (0.60), % water-stable macro-aggregates (0.61), and soil water retention at –0.033 MPa (0.75) and –1.5 MPa (0.72), and negative correlation with bulk density (–0.70) for the surface 0–0.15 m soil. The study thus suggests that application of balanced mineral fertilisers in combination with organic manure sustains a better soil physical environment and higher crop productivity under intensive cultivation.
A protocol for converting qualitative point soil pit survey data into continuous soil property maps
Authors: Taylor James A. , Minasny Budiman
Published: August 2006

Vineyard soil surveys to date have focused on presenting soil data in point rather than raster format. This is due to the recording of both numeric and categorical variables. A protocol, including a lookup table to transform linguistic texture values into particle size distributions, to convert point data into continuous raster maps is presented. The resulting maps are coherent with vineyard knowledge and provide a strong spatial representation of soil variability within the vineyard. Validation with an independent dataset shows an error of ~10% in prediction; however, some of this can be attributed to errors in the geo-rectification of old data. Raster maps allow the survey data to be incorporated into computer systems to better model vineyard and irrigation designs and are more readily used in day-to-day vineyard management decisions.
Infiltrating neutrophils mediate the initial angiogenic switch in a mouse model of multistage carcinogenesis
Authors: Nozawa Hiroaki , Chiu Christopher , Hanahan Douglas
Published: August 2006

Matrix metalloprotease type 9 (MMP-9) has been functionally implicated in VEGF activation, the induction and maintenance of chronic angiogenesis, and early stage tumor growth in a number of mouse models of cancer. In this article, we have identified two inflammatory cell types that are major sources of MMP-9 in the angiogenic stages of pancreatic islet carcinogenesis that unfold in RIP1-Tag2 transgenic mice. MMP-9-expressing neutrophils were predominantly found inside angiogenic islet dysplasias and tumors, whereas MMP-9-expressing macrophages were localized along the periphery of such lesions. Transient depletion of neutrophils significantly suppressed VEGF:VEGF-receptor association, a signature of MMP-9 activity, and markedly reduced the frequency of initial angiogenic switching in dysplasias. Thus infiltrating neutrophils can play a crucial role in activating angiogenesis in a previously quiescent tissue vasculature during the early stages of carcinogenesis.