bluuebunny/crossref_metadata_2025 huggingface dataset:
Low leakage current optically gated silicon field emitter arrays
Authors: Liu Kendrick X. , Heritage Jonathan P.
Published: February 2003

Gated silicon emitters (50×50 emitters at 20 μm spacing) having a “volcano” shape were fabricated by a dry etching-based technique. The insulating oxide layers formed by wet oxidation and low pressure chemical vapor deposition were ∼1 μm thick, and the Cr/Au film was deposited to function as the gate electrode. Quantum efficiency and dynamic range of photoenhanced field emission from gated silicon field emitter arrays improve at the expense of higher dark current (current with no photoexcitation) as the gate voltage is increased. For 830 nm photoexcitation, efficiency approached 29% at 130 V, and ratio of photocurrent to dark current peaked at 5.5 at 80 V. Measured saturation behavior was attributed to screening of the applied field by photogenerated electrons. Optical excitation with ∼10 ns pulses at 1064 nm revealed shorter anode current pulses at increasing gate bias consistent with an increase in collected drift electrons due to an increase in depletion layer thickness. Also, the ratio of anode current to gate current reached a high of 820 at 30 V.
Profile control of high aspect ratio trenches of silicon. II. Study of the mechanisms responsible for local bowing formation and elimination of this effect
Authors: Boufnichel M. , Aachboun S. , Lefaucheux P. , Ranson P.
Published: February 2003

Profile control of deep and narrow anisotropic trenches in silicon has been investigated in a low-pressure high-density plasma reactor working with a SF6/O2 plasma mixture. The aim is to achieve deep trenches with high aspect ratio (depth/width>10), high anisotropy, high selectivity (silicon/SiO2 mask>300:1), high etch rate (>5 μm/min) and with no local bowing. This study focuses on a cryogenic etching method. In the previous article [M. Boufnichel et al., J. Vac. Sci. Technol. B 20, 1508 (2002)] we presented a parametrical study of the evolution of local bowing as a function of the process conditions. Here we present a complete study of the mechanisms involved in the creation of local bowing at the top of deep narrow trenches, and in particular the effect (influence) of the characteristics (nature, thickness, and side slope) on local bowing. Explanations for the appearance of local bowing are given and targeted experiments are performed to eliminate it. The final performance shows that we are now able to etch a minimum of 60 μm in depth for a 4 μm trench aperture with no local bowing at a high etch rate of about 5.5 μm/min with a cryogenic method in which no cleaning step is necessary unlike for the Bosh process [M. J. Walker, Proc. SPIE 4407 (2001)].
Thick and thermally isolated Si microheaters for microfabricated preconcentrators
Authors: Tian W.-C. , Pang S. W.
Published: February 2003

Thick thermally isolated microheaters in Si are fabricated using high aspect ratio etching technology. These thick microheaters a with large surface area provide the large adsorbent capacity needed for high sensitivity microfabricated preconcentrators in a microgas chromatography system. In addition, air gaps around the microheaters provide good thermal isolation to lower the power consumption. A 520 μm thick Si microheater with good thermal isolation has been made and its back side is anodically bonded to a pyrex glass substrate. To provide good thermal isolation, a 500 μm wide air gap around the microheater, thin poly-Si interconnects on top of dielectric membrane, and air gap isolation from the bottom glass substrate are used. Microheaters with a 500 μm air gap can be heated up 50% faster to a temperature of 270 °C compared to those with a 100 μm air gap, while the power consumption is 25% less and there is a larger temperature difference between the microheater and the bonding area. Operating the microheater in a vacuum results in lower power consumption. At 250 °C, 35% less power is needed at 1.2 Torr compared to atmospheric pressure. The power consumption is further reduced by minimizing the contact area with the heater support substrate. Up to 34% power reduction has been demonstrated by placing heaters on a thin membrane or etching trenches in the supporting substrate. These thick thermally isolated Si microheaters can provide good power efficiency, large adsorbent capacity, and high mechanical strength for microfabricated preconcentrators.
High-power collimated laser-plasma source for proximity x-ray nanolithography
Authors: Gaeta C. J. , Rieger H. , Turcu I. C. E. , Forber R. A. , Campeau S. M. , Cassidy K. L. , Powers M. F. , Stone A. , Maldonado J. R. , Mrowka S. , French G. , Naungayan J. , Kelsy C. , Hark P. , Morris J. H. , Foster R. M. , Carosella J. C. , Fleming D. , Selzer R. , Siegert H. , Smith H. I. , Lim M. H. , Cheng Z. , Burdett J. , Gibson D. , Whitlock R. R. , Dozier C. M. , Newman D. A.
Published: February 2003

A compact laser-produced plasma x-ray source radiates 1 nm x rays with an average power of 24 W in 2π steradians. The x-ray conversion efficiency is 9% of the laser power delivered on target. The 300 W laser power is generated by a compact diode-pumped, solid-state Nd:YAG laser system. The point source x-ray radiation is collimated with a polycapillary optic to a parallel x-ray beam. The collimated plasma source (CPS) is used to demonstrate proximity x-ray lithography of 100 nm lines with a 16 μm gap between the mask and wafer. The CPS is optimized for integration with an x-ray stepper to provide a complete collimated plasma lithography exposure tool for the manufacture of high-speed GaAs devices.
Behavior of the solid-state field-controlled planar emitters under extreme working conditions
Authors: Binh Vu Thien , Semet V. , Dupin J. P. , Adessi Ch. , Guillot D.
Published: February 2003

In this article we present the emission properties of planar solid-state field-controlled emission cold cathodes under extreme conditions, in particular about the highest limit for current densities on one hand and on the other hand about the highest gas pressures that can be supported by these cathodes under continuous electron emission. The experimental results are discussed in correlation with the measured energy distribution of the emitted electrons.
Field emission characterization of silicon tip arrays coated with GaN and diamond nanoparticle clusters
Authors: Hajra M. , Chubun N. N. , Chakhovskoi A. G. , Hunt C. E. , Liu K. , Murali A. , Risbud S. H. , Tyler T. , Zhirnov V.
Published: February 2003

Wide band-gap materials show promise for applications in coating of field emission tips. Recently nanocrystalline hexagonal GaN crystallites as small as 12 nm average diameter have been formed using reactive laser ablation of gallium metal in nitrogenating ambient [T. J. Goodwin et al., Appl. Phys. Lett. 70, 3122 (1997)]. In this article we investigated the performance of ungated emitters with and without surface coating. Silicon tip arrays are coated by dielectrophoresis of gallium nitride nanoparticles or nanocrystalline diamond clusters from an ethanol suspension. The emitters were evaluated and compared before and after the surface treatment using SEM image and I–V measurements in the diode configuration. The results suggest that the emitters benefit from coating the surface with nanocrystalline diamond clusters in terms of reduction in the turn on voltage by 100 V and increase uniformity in emission during low voltage operation. The long-term emission stability for both types of the coated cathodes was studied over a period of 90 h. The emitters coated with GaN nanoparticle clusters show a significant improvement in the current fluctuation from 150% (for untreated cathodes) to 50%.
Bonding and band offset in N2O-grown oxynitride
Authors: Gritsenko V. A. , Wong Hei , Kwok W. M. , Xu J. B.
Published: February 2003

Using high-resolution angle-resolved x-ray photoelectron spectroscopy (ARXPS) measurements, the chemical bonding, and valance-band offset of ultrathin (16 and 24 Å) N2O-grown oxide were studied. We confirmed that the composition of N2O-grown oxide is mainly silicon oxide with both the concentration and band offset values measured using ARXPS. The surface density of nitrogen is about (3±1)×1014 cm−2 near the Si/dielectric interface. The valence- and conduction-band offsets for N2O-grown oxide are the same as those for the Si/SiO2 interface because the nitrogen content is too low to have any pronounced effects. In addition, we found that most of the nitrogen atoms at the interface appeared in the form of Si–N bonding instead of N–O bonding.
Influence of seed layers on microstructure and electrical properties of indium-tin oxide films
Authors: Han Younggun , Kim Donghwan , Cho Jun-Sik , Koh Seok-Keun
Published: February 2003

Films of indium-tin oxide (ITO) were deposited by ion-beam sputtering. Two types of seed layers of ITO were deposited prior to bulk-layer deposition. The types of seed layers were determined by ion species, namely, either pure Ar+ or a mixture of Ar+ and O2+. The microstructure and the preferred orientation of the bulk films mimicked those of the seed layer. Films with larger grains were obtained when the seed layer was used. The electron mobility did not depend on the type of microstructure. The ability to control the microstructure without sacrificing the electrical conductivity was demonstrated.
Dielectric-carbon composites for field electron emitters
Authors: Karabutov A. V. , Ralchenko V. G. , Vlasov I. I. , Gordeev S. K. , Korchagina S. B.
Published: February 2003

Diamond/carbon composites are one type of material showing very low-field electron emission. In the present work, dielectric/carbon nanocomposites have been prepared in which diamond particles were replaced with insulating particles of SiO2 and BN (in cubic or hexagonal forms). The samples were produced by a pyrolytic carbon deposition inside a porous dielectric compact. The average thickness of the pyrocarbon shells covering the dielectric particles varied from 0.4 to 40 nm to find the optimal structure for efficient emission. The best samples of the composites showed excellent field-emission properties with threshold fields of as low as 0.5–1 V/μm, good surface uniformity, and long-term stability that is very similar to diamond/carbon composites. The electronic properties of the emission centers (work function, electrical resistivity, topography, and emission intensity) were investigated with a special scanning tunneling microscopy device. No correlation between the location and topography features (tips or pits) of the emission center was found; rather, the centers often correspond to regions with low values of work function and high electrical resistivity. The emission mechanism is considered using quantum properties of nanostructured carbon forms, specifically taking into account a reduction of the tunneling barrier on an insulator/graphite interface due to quantum well effects in thin (two-dimensional) carbon layers on a dielectric surface.
Growth temperature dependence of substitutional carbon incorporation in SiGeC/Si heterostructures
Authors: Loup V. , Hartmann J. M. , Rolland G. , Holliger P. , Laugier F. , Séméria M. N.
Published: February 2003

We have studied in reduced-pressure chemical vapor deposition the influence of the growth temperature on the interstitial-substitutional carbon incorporation ratio in SiGeC. Si1−yCy as well as high- and low-Ge concentration Si1−x−yGexCy layers were grown at 550, 600, and 650 °C. X-ray diffraction (XRD) and secondary ion mass spectrometry (SIMS) were used in order to determine the substitutional and the total (interstitial+substitutional) carbon concentrations. As far as high-Ge concentration Si1−x−yGexCy layers are concerned, compressively strained layers with up to 1.74% (1.26% and 0.62%) in substitutional carbon atoms were grown at 550 °C (600 and 650 °C). Low-Ge concentration Si1−x−yGexCy layers have also been grown. We have managed through the increase of the SiCH6 mass flow to tailor the Si1−x−yGexCy layer strain from compressive to tensile. The highest substitutional carbon concentrations obtained are 1.51% (1.21% and 0.92%) for growth temperatures of 550 °C (600 and 650 °C). Si1−yCy/Si tensile-strained heterostructures were also grown. The highest substitutional carbon concentration incorporated is around 1.44% (1.12% and 0.83%) at 550 °C (600 and 650 °C). Varying the Si1−x−yGexCy and Si1−yCy layers growth temperature does not seem to impact upon the total carbon incorporation. However, by comparing SIMS and XRD data, we showed that the more the temperature increases, the more the substitutional/interstitial carbon incorporation ratio is reduced.
Ta metallization of Si–O–C substrate and Cu metallization of Ta/Si–O–C multilayer
Authors: Tong J. , Martini D. , Magtoto N. , Kelber J.
Published: February 2003

Interfacial reactions of Ta with a Si–O–C low-dielectric constant (low-k) material and Cu/Ta/Si–O–C multilayers are investigated using x-ray photoelectron spectroscopy (XPS) and cross-sectional transmission electron microscopy (TEM). Data indicate that Ta deposition on the low-k substrate results in the initial formation of Ta oxide and TaC. Subsequent deposition of Ta eventually results in the formation of a metallic Ta overlayer at 300 K. The thickness of the initial Ta oxide/TaC-containing layer varies with the Ta deposition rate. At a deposition rate of ∼1 Å min−1, no metallic Ta is observed, even after 32 min sputter deposition time. In contrast, a film of roughly the same thickness, obtained after 15 s deposition at a rate of ∼2 Å s−1, is predominantly metallic Ta. Sputter deposition rates, derived from XPS data, are in agreement with film thicknesses derived from cross-sectional TEM data. Heating of Ta/low-k films in UHV results in no significant changes (as detected by XPS) up to 800 K. Cu deposited by sputter deposition onto a low-k surface covered with metallic Ta exhibits conformal growth, whereas 3d islanding is observed on a surface where TaC and Ta oxide are present. Cu diffusion into the bulk substrate is not observed at temperatures below 800 K in UHV.
Deposition of SiO2 layers on 4H–SiC by photochemical vapor deposition
Authors: Chiou Yu-Zung , Chang Chia-Sheng , Chang Shoou-Jinn , Su Yan-Kuin , Chiou Jung-Ran , Huang Bohr-Ran , Chen Jone F.
Published: February 2003

SiO 2 insulating layers were deposited onto 4H–SiC substrates by a photochemical vapor deposition (photo-CVD) technique. It was found that the SiO2 growth rate increases linearly with total SiH4/O2 density for a fixed ratio of SiH4 and O2 partial pressure, due to the increasing densities of SiH2 and excited O atoms. It was also found that the interface state density, Dit, is equal to 3.27×1012, 3.16×1012, and 5.66×1011 cm−2 eV−1 for photo-CVD SiO2 layers prepared at 150, 300, and 500 °C, respectively. Furthermore, it was found that the leakage current was only 4.15×10−8 A/cm2 with an applied field of 4 MV/cm for the 500 °C photo-CVD grown Al/SiO2/4H–SiC metal–insulator–semiconductor capacitor.
Energies and Dipole Moments of Excited States of Ozone and Ozone Radical Cation Using Fock Space Multireference Coupled-Cluster Analytical Response Approach
Authors: Ajitha Devarajan , Hirao Kimihiko , Pal Sourav
Published: February 2003

Using the Fock space multireference coupled-cluster (FS-MRCC) analytical linear response approach, we report the dipole moments of low-lying singlet and triplet excited states of ozone. The low-lying singlet and triplet excited states are calculated at the ground-state geometry and at the adiabatic geometry for the 1A2 and 1B1. For comparison we also calculate at the ground-state geometry the dipole moments of the 1A2, 1B1 and 1B2 using multireference configuration interaction (MRCI) with a bigger VQZ basis and complete active space. We also report as by-product the excitation energy values in the singles and doubles approximation. At the ground-state geometry we also report the energy and the dipole moments of the 2A1, 2A2 and 2B1 states of the ozone radical cation. The energy of the ozone cation radical is compared with the other correlated approaches. It matches well with the experimental values.
On the Concerted Ring Opening of Protonated Squalene Oxide and A-Ring Formation in the Biosynthesis of Lanosterol
Authors: Hess B. Andes
Published: February 2003

Density functional calculations were performed on a model system of squalene oxide to study the mechanism of the formation of ring A in the biosynthesis of lanosterol from squalene. When (2Z)-6,7-epoxy-3,7-dimethyloct-2-ene was protonated, it was calculated to undergo a very facile ring opening of the oxirane in concert with the formation of the six-membered ring of the 4-(hydroxymethyl)-1,2,3,3-tetramethy1cyclohexyl cation. A study of the reaction pathway (IRC) indicates a very early transition structure in which the carbon- carbon double bond participates anchimerically in the ring-opening of the protonated oxirane. It is suggested that the primary role of the enzyme in this first step of the biosynthesis of lanosterol is protonation of the oxirane ring along with holding the substrate in the proper conformation for the concerted ring-closure to occur. The similarity between this mechanism and that recently proposed for concerted C-ring expansion and D-ring formation in the biosynthesis of lanosterol is discussed.
Origin of the Odd-twins anomaly: magnetic effect of a unique stratigraphic marker in the Appalachian foreland basin, Gulf of St. Lawrence
Authors: Waldron John WF , DeWolfe Jerry , Courtney Robert , Fox Doris
Published: February 2003

The "Odd-twins magnetic anomaly" is a pair of linear asymmetric positive anomalies located in the Gulf of St. Lawrence, over the post-Taconian, pre-Acadian foreland basin fill related to the development of the Appalachians. A marine magnetic survey allowed the anomaly to be traced close to the coast of Newfoundland, and an on-land survey identified both peaks within the area of outcrop of the Late Ordovician Long Point Group. Sandstones of high susceptibility sampled from sparse outcrops close to the locations of the anomaly peaks contain up to 0.58% magnetite. Models involving dipping sheets of sandstone having similar and slightly higher susceptibility can explain both the onshore and offshore anomaly. The magnetite is of detrital origin and represents a paleoplacer heavy mineral concentration formed in a marginal marine environment. The anomaly provides a unique tie point between the known onshore stratigraphy and the succession in the foreland basin, known only from industry seismic profiles. This tie point indicates that nearly half of the recorded subsidence of the post-Taconian foreland basin took place in the Late Ordovician, suggesting that a major event within the Appalachian orogen loaded the Laurentian margin at this time. A subsequent hiatus, representing the Early Silurian, may record thermal uplift associated with the Salinian orogeny. Renewed Late Silurian to Devonian loading and sedimentation resulted from the Acadian orogeny.
Marine reptiles from the Nanaimo Group (Upper Cretaceous) of Vancouver Island
Authors: Nicholls Elizabeth L , Meckert Dirk
Published: February 2003

A new fauna of fossil marine reptiles is described from the Late Cretaceous Nanaimo Group of Vancouver Island. The fossils are from the Haslam and Pender formations (upper Santonian) near Courtenay, British Columbia, and include elasmosaurid plesiosaurs, turtles, and mosasaurs. This is only the second fauna of Late Cretaceous marine reptiles known from the Pacific Coast, the other being from the Moreno Formation of California (Maastrichtian). The new Nanaimo Group fossils are some 15 million years older than those from the Moreno Formation. However, like the California fauna, there are no polycotylid plesiosaurs, and one of the mosasaurs is a new genus. This reinforces the provinciality of the Pacific faunas and their isolation from contemporaneous faunas in the Western Interior Seaway.
Late Middle Ordovician olistostrome formation and magmatism along the Red Indian Line, the Laurentian arc  Gondwanan arc boundary, at Sops Head, Newfoundland
Authors: McConnell Brian J , O'Brien Brian H , Nowlan Godfrey S
Published: February 2003

The Sops Head Complex of Badger Bay, central Newfoundland, includes olistostromal and tectonized mélanges and marks the Red Indian Line, the boundary between the peri-Gondwanan Exploits and peri-Laurentian Notre Dame subzones of the oceanic Dunnage Zone. Basalts in the olistostromal mélange preserve peperitic contacts with mudstone and limestone within slumped sedimentary units, demonstrating that magmatism was coeval with olistostrome formation. Conodonts from the limestones date these events as late Darriwilian ("Llandeilian," Middle Ordovician) in age. The conodont fauna consists entirely of North Atlantic Faunal Realm elements, suggesting a peri-Gondwanan or mid-Iapetan provenance for limestone of the Sops Head Complex. Basalt geochemistry suggests magmatism in a mature volcanic-arc to back-arc setting. The Sops Head Complex shows similarities in age, provenance, and stratigraphic setting to the Dunnage Mélange, suggesting that the two units are correlative.
IRREDUCIBILITY AND SMOOTHNESS OF THE MODULI SPACE OF MATHEMATICAL 5-INSTANTONS OVER ℙ3
Authors: COANDĂ I. , TIKHOMIROV A. , TRAUTMANN G.
Published: February 2003

We prove that the space of mathematical instantons with second Chern class 5 over ℙ3 is smooth and irreducible. Unified and simple proofs for the same statements in case of second Chern class ≤ 4 are contained.
HEAT KERNELS FOR PERTURBED DIRAC OPERATORS ON EVEN-DIMENSIONAL MANIFOLDS WITH BOUNDED GEOMETRY
Authors: FOX JEFFREY , HASKELL PETER
Published: February 2003

This paper establishes conditions under which one can use integrals of locally defined differential forms to give an asymptotic expansion of the supertrace of the heat operator associated with a perturbed Dirac operator on a complete noncompact even-dimensional manifold with bounded geometry.
ON THE DIVISOR CLASS GROUP OF 3-FOLD SINGULARITIES
Authors: CAIBĂR MIREL
Published: February 2003

In this note we calculate the divisor class number of an isolated canonical singularity [Formula: see text], which is assumed to be nondegenerate with respect to its Newton polyhedron, in terms of a suitable set of monomials whose residue classes form a basis for the Milnor algebra of f.
THE ALEXANDER POLYNOMIAL OF A PLANE CURVE SINGULARITY AND INTEGRALS WITH RESPECT TO THE EULER CHARACTERISTIC
Authors: CAMPILLO A. , DELGADO F. , GUSEIN-ZADE S. M.
Published: February 2003

It was shown that the Alexander polynomial (of several variables) of a (reducible) plane curve singularity coincides with the (generalized) Poincaré polynomial of the multi-indexed filtration defined by the curve on the ring [Formula: see text] of germs of functions of two variables. The initial proof of the result was rather complicated (it used analytical, topological and combinatorial arguments). Here we give a new proof based on the notion of the integral with respect to the Euler characteristic over the projectivization of the space [Formula: see text] — the notion similar to (and inspired by) the notion of the motivic integration.
DYNAMICS AND HOLOGRAPHIC DISCRETENESS OF TACHYONIC INFLATION
Authors: WANG BIN , ABDALLA ELCIO , SU RU-KENG
Published: February 2003

We consider issues related to tachyonic inflation with inverse-power-law potential. We find the solution of the evolution equations in the slow-roll limit in FRW as well as in the brane cosmology. Using the holographic entropy bound, we estimate the quantum-gravitational discreteness of tachyonic inflation perturbations.
MIXING IN THE D0 SYSTEM RESULTS FROM COLLIDER EXPERIMENTS
Authors: GROTHE MONIKA
Published: February 2003

Mixing in the D0 system may provide a sensitive probe for new physics beyond the Standard Model (SM) but has so far eluded experimental observation. The SM predictions are typically small (< 10-3) for the mixing parameters x, y which, in the absence of charge-parity (CP) symmetry violation, measure the mass (x = Δ m/Γ) and lifetime (y = ΔΓ/2Γ) difference of the CP eigenstates in the D0 system. The asymmetric B-factory experiments BABAR and Belle open up the opportunity of measuring x, y with unprecedented statistical precision and sample purities. Results from BABAR and Belle, and from CLEO are reviewed.
A 3‐D resistivity investigation of a contaminated site at Lernacken, Sweden
Authors: Dahlin Torleif , Bernstone Christian , Loke Mong Hong
Published: February 2003

A contaminated site at Lernacken in southern Sweden, formerly used for sludge disposal, was investigated using a 3‐D resistivity imaging technique. The data acquisition was carried out using a roll‐along technique for 3‐D data acquisition that allows using standard multielectrode equipment designed for engineering and environmental applications. The technique allows for the measurement of large true 3‐D resistivity data sets, and data were measured using two perpendicular electrode‐orientation directions with only one layout of the cables. The data were plotted as two sets of pseudo depth slices using the two electrode orientation directions, which resulted in markedly different plots. The complete data set was inverted to form a resistivity‐depth model of the ground using a 3‐D least‐squares smoothness constrained inversion technique. The results obtained were compared to other geophysical and background data, and a good agreement was found. The results show that the 3‐D roll‐along technique in combination with 3‐D inversion can be highly useful for engineering and environmental applications. However, multichannel measurement equipment is necessary to speed up the data acquisition process for routine application.
Interpolation of geophysical data using continuous global surfaces
Authors: Billings Stephen D. , Beatson Rick K. , Newsam Garry N.
Published: February 2003

A wide class of interpolation methods, including thin‐plate and tension splines, kriging, sinc functions, equivalent‐source, and radial basis functions, can be encompassed in a common mathematical framework involving continuous global surfaces (CGSs). The difficulty in applying these techniques to geophysical data sets has been the computational and memory requirements involved in solving the large, dense matrix equations that arise. We outline a three‐step process for reducing the computational requirements: (1) replace the direct inversion techniques with iterative methods such as conjugate gradients; (2) use preconditioning to cluster the eigenvalues of the interpolation matrix and hence speed convergence; and (3) compute the matrix–vector product required at each iteration with a fast multipole or fast moment method.

We apply the new methodology to a regional gravity compilation with a highly heterogeneous sampling density. The industry standard minimum‐curvature algorithms and several scale‐dependent CGS methods are unable to adapt to the varying data density without introducing spurious artifacts. In contrast, the thin‐plate spline is scale independent and produces an excellent fit. When applied to an aeromagnetic data set with relatively uniform sampling, the thin‐plate spline does not significantly improve results over a standard minimum‐curvature algorithm.
Quantitative measures of image resolution for seismic survey design
Authors: Gibson Richard L. , Tzimeas Constantinos
Published: February 2003

Illumination and fold analyses can provide valuable information for the design of seismic surveys, but generally they do not provide quantitative results that are directly related to the seismic images that would be obtained using a proposed acquisition geometry. On the other hand, the Beylkin (1985) equation predicts the spatial resolution of prestack migration using the acquisition geometry and an earth model, providing a simple yet effective tool for survey design. Calculations for a simple homogeneous earth model demonstrate the advantages of this approach. Specifically, the variations in spatial resolution within the model show that the best resolution results from singlefold, zero‐offset experiments for very simple acquisition geometries. Applications of the same design method to a realistic salt model show that some results are not surprising, such as decreases in resolution beneath the salt structure. However, the best resolution beneath the salt is obtained with the maximum offset for a trial single‐cable marine geometry, not the zero‐offset source–receiver pairs. This is a consequence of ray bending by the salt structure and the geometry of the acquisition lines. The result clearly demonstrates the utility of the proposed survey design tool. We also find that a land circular source/radial receiver line array design shows strong potential for improved resolution over the simple marine geometry. Furthermore, tests show that the land survey should display more robust results as the S/N ratio decreases.
Applications of plane‐wave destruction filters
Authors: Fomel Sergey
Published: February 2003

Plane‐wave destruction filters originate from a local plane‐wave model for characterizing seismic data. These filters can be thought of as a time–distance (T‐X) analog of frequency‐distance (F‐X) prediction‐error filters and as an alternative to T‐X prediction‐error filters. The filters are constructed with the help of an implicit finite‐difference scheme for the local plane‐wave equation. Several synthetic and real data examples show that finite‐difference plane‐wave destruction filters perform well in applications such as fault detection, data interpolation, and noise attenuation.
Synthesis of polyaniline using horseradish peroxidase immobilized on plasma‐functionalized polyethylene surfaces as initiator
Authors: Alvarez S. , Manolache S. , Denes F.
Published: February 2003

The doping of semiconducting conjugated polymers (e.g., polyaniline, PANI) can result in the elimination of the bandgap, leading to high electrical conductivities (comparable to metals). Doped PANI is totally insoluble and thus nonprocessable, which considerably limits its practical applications. Synthesis of PANI using immobilized horseradish peroxidase (HRP) as a catalyst in aqueous solutions can open up additional possibilities for applications through the direct synthesis of controlled‐thickness PANI layers on various substrate surfaces. The RF plasma‐enhanced surface functionalization of polyethylene and the covalent immobilization of HRP are discussed, and the polymerization of aniline initiated by immobilized HRP is presented. The nature of plasma‐grafted surface functionalities on the substrate surfaces and the formation of PANI are demonstrated using X‐ray photoelectron spectroscopy and attenuated total reflectance Fourier transform IR spectroscopy. The molecular weight distribution of PANI is evaluated with gel permeation chromatography, and the activity of the immobilized enzyme is monitored using UV spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 369–379, 2003
The characteristic properties of poly(methyl methacrylate)/polystyrene core‐shell composite polymer latex
Authors: Lee Chia‐Fen
Published: February 2003

In this study, the poly(methyl methacrylate/polystyrene (PMMA/PS) core‐shell composite latex was synthesized by the method of soapless seeded emulsion polymerization. The morphology of the PMMA/PS composite latex was core‐shell structure, with PMMA as the core and PS as the shell. The core‐shell morphology of the composite polymer latex was found to be thermally unstable. Under the effect of thermal annealing, the PS shell region first dispersed into the PMMA core region, and later separated out to the outside of the PMMA core region. This was explained on the basis of lowing interfacial tension between the PMMA and PS phases owing to the interpenetration layer. The interpenetration layer, which was located at the interface of the core and shell region, contained graft copolymer and entangled polymer chains. Both the graft copolymer and entangled polymer chains had the ability to lower the interfacial tension between the PMMA and PS phases. Also, the effect of thermal annealing on the morphology of commercial polymer/composite latex polymer blends was examined. The result showed that the core‐shell composite latex had the ability to enhance the compatibility of the components of polymer blends. The compatibilizing ability of the core‐shell composite latex was better than that of a random copolymer. Moreover, the effect of the amount of core‐shell composite latex on the morphology of the polymer blend was investigated. The polymer blends, which contained composite latex above 50% wt, showed the morphology of a double sea‐island structure. In addition, the composite latex was completely dissolved in solvent to destroy the core‐shell structure and release the entangled polymer chains, and then dried to form the entangled free composite polymer. The entangled free composite polymer had the ability to enhance the compatibility of the components of the polymer blend as usual. The weight ratio 3/7 commercial polymer/entangled free composite polymer blend showed the morphology of the phase inversion structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 312–321, 2003
Effect of styrene–isoprene–styrene, styrene–butadiene–styrene, and styrene–butadiene–rubber on the mechanical, thermal, rheological, and morphological properties of polypropylene/polystyrene blends
Authors: Raghu P. , Nere C. K. , Jagtap R. N.
Published: February 2003

The mechanical, thermal, rheological, and morphological properties of polypropylene (PP)/polystyrene (PS) blends compatibilized with styrene–isoprene–styrene (SIS), styrene–butadiene–styrene (SBS), and styrene–butadiene–rubber (SBR) were studied. The incompatible PP and PS phases were effectively dispersed by the addition of SIS, SBS, and SBR as compatibilizers. The PP/PS blends were mechanically evaluated in terms of the impact strength, ductility, and tensile yield stress to determine the influence of the compatibilizers on the performance properties of these materials. SIS‐ and SBS‐compatibilized blends showed significantly improved impact strength and ductility in comparison with SBR‐compatibilized blends over the entire range of compatibilizer concentrations. Differential scanning calorimetry indicated compatibility between the components upon the addition of SIS, SBS, and SBR by the appearance of shifts in the melt peak of PP toward the melting range of PS. The melt viscosity and storage modulus of the blends depended on the composition, type, and amount of compatibilizer. Scanning electron microscopy images confirmed the compatibility between the PP and PS components in the presence of SIS, SBS, and SBR by showing finer phase domains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 266–277, 2003
Surface of cellulosic materials modified with functionalized polyethylene coupling agents
Authors: Li Qingxiu , Matuana Laurent M.
Published: February 2003

The interfacial adhesion between a wood fiber and a plastic matrix strongly influences the performance of wood‐fiber‐reinforced thermoplastic composites. Fiber surface modification with coupling agents is generally needed to induce bond formation between the fiber and polymer matrix. This study investigated the chemical reactions between cellulosic materials and functionalized polyethylene coupling agents. Both wood flour and cotton cellulose powder were treated with acrylic acid‐functionalized polyethylene and maleic anhydride‐functionalized polyethylene (maleated polyethylene) for surface modifications, and chemical changes resulting from these treatments were followed by a study of the Fourier transform infrared and X‐ray photoelectron spectroscopy spectra. Variations in the band intensities, oxygen‐to‐carbon ratios, and concentrations of unoxidized carbon atoms were related to changes that occurred on the surfaces of modified cellulosic materials. The experimental results indicated that chemical bonds between the hydroxyl groups of the cellulosic materials and the functional groups of the coupling agents occurred through esterification reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 278–286, 2003
Effect of the addition mode of cycloaliphatic diepoxide on the morphology and film properties of crosslinkable core‐shell latex
Authors: Teng Ganghua , Soucek Mark D. , Yang Xiaofan F. , Tallman Dennis E.
Published: February 2003

Core‐shell latexes (LAs) designed for crosslinking with cycloaliphatic diepoxide were synthesized. The core contained methyl methacrylate (MMA), butyl acrylate (BA), and 2‐hydroxyethyl methacrylate, and the shell was prepared with MMA, BA, and methacrylic acid. The crosslinker was coemulsified with the monomer and added during the LA preparation or after the polymerization either as an emulsion or in an organic solvent. The morphology of the LA was studied with atomic force microscopy and transmission electron microscopy. We used titration to establish the acid distribution. The water absorption and tensile and viscoelastic properties of the LA films were investigated as a function of the addition mode of the cycloaliphatic diepoxide crosslinker. The solution approach generally provided better mechanical properties than the emulsion approach, and the addition of epoxide during the polymerization lowered the water adsorption and hardness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 245–257, 2003
Deposition of poly(diphenylamine‐co‐o‐chloroaniline) by pulse potentiostatic method: Growth equation and characterization
Authors: Rajendran V. , Gopalan A. , Buvaneswari R. , Vasudevan T. , Wen Ten‐Chin
Published: February 2003

Electrochemical copolymerization of diphenylamine (DPA) with o‐chloroaniline (OCA) was performed in aqueous 4M sulfuric acid using the pulse potentiostatic method (PPSM). By employing the tunable parameters in PPSM, polymeric films were deposited under different conditions. Cyclic voltammetry was used for evaluating the characteristics of the deposited polymeric films. A suitable growth equation for the deposition of polymer, relating the charge associated for the film deposition and the pulse parameters in PPSM, was deduced. Various surface parameters are evaluated. The formation of copolymer during PPSM deposition was revealed through critical analysis of the results. The characteristic differences between the individual homopolymers, poly(diphenylamine) and poly(o‐chloroaniline) and the copolymer, poly(diphenylamine‐co‐o‐chloroaniline), were brought out. The copolymer was also synthesized through a chemical method and characterized through infrared and ultraviolet‐visible spectroscopic analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 389–397, 2003
Effects of an organic phosphorus nucleating agent on crystallization behaviors and mechanical properties of poly(propylene)
Authors: Gui Quande , Xin Zhong , Zhu Weiping , Dai Gance
Published: February 2003

The effects of an organic phosphorus nucleating agent on the crystallization behavior and mechanical properties of poly(propylene) were investigated. As the concentration of nucleating agent increased from 0 to 0.8%, the tensile and flexural strengths of the nucleated poly(propylene) resin increased by 15%, the flexural modulus increased by 35%, the crystallization peak temperature increased by 10°C, and the nucleation density (calculated with the nonlinear Voltrra integral equation) increased by 106 times. Mechanical properties increased with nucleation density. Linear equations between the mechanical properties and the logarithmic nucleation density were revealed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 297–301, 2003
Properties of soy protein isolate/poly(ethylene‐co‐ethyl acrylate‐co‐maleic anhydride) blends
Authors: Zhong Zhikai , Sun Susan X.
Published: February 2003

Blends of soy protein isolate (SPI) with 10, 20, 30, 40, and 50% poly(ethylene‐co‐ethyl acrylate‐co‐maleic anhydride) (PEEAMA), with or without addition of 2.0 wt % methylene diphenyl diisocyanate (MDI), were prepared by mixing with an intensive mixer at 150°C for 5 min, and then milling through a 1‐mm sieve. Blends were then compression‐molded into a tensile bar at 140°C. Thermal and mechanical properties and water absorption of the blends were studied by differential scanning calorimetry (DSC), dynamical mechanic analysis (DMA), a test of modulus and tensile strength (with an Instron tensile tester), a water absorption test, and scanning electron microscopy (SEM). The blends showed two composition‐dependent glass transition temperatures. Furthermore, as the SPI content increased, the melting temperature of PEEAMA remained constant but the heat of fusion decreased. These results indicate that SPI and PEEAMA were partially miscible. Morphology observations support these results. Increasing the PEEAMA content resulted in decreases in the modulus and tensile strengths and increases in the elongation and toughness of the blends. Water absorption of the blends also decreased with increased PEEAMA content. Incorporating MDI further decreased the water absorption of the blends. The mechanism of water sorption of SPI was relaxation controlled, and that of the blends was diffusion controlled. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 407–413, 2003
Ways of strengthening biodegradable soy‐dreg plastics
Authors: Zhang Lina , Chen Pu , Huang Jin , Yang Guang , Zheng Lianshuang
Published: February 2003

Biodegradable plastics (GSD) based on soy dreg (SD) were prepared by compression‐molding, with glycerol as the plasticizer and glutaraldehyde (GA) as the cross‐linker. The structure and properties of the GSD sheets were investigated by Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), scanning electron microscope (SEM), and tensile test methods. The results indicate that when GA content was 6.8%, the tensile strength (σb) of the sheet reached the maximum value of 14.5 MPa. Moreover, the strength and water resistance of the sheets coated with castor‐oil‐based polyurethane/nitrochitosan interpenetrating network (IPN) coating were significantly enhanced to 24.6 MPa in the dry state and 9.8 MPa in the wet state. Simultaneously, the test of biodegradability of the GSD sheet in a mineral salts medium containing microorganisms and agar proved that GSD could be fully biodegradable. This work has provided a novel way to utilize low‐cost SD to prepare biodegradable plastics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 422–427, 2003
Preparation of micrometer‐sized, monodisperse, magnetic polymer particles
Authors: Okubo M. , Minami H. , Komura T.
Published: February 2003

Micrometer‐sized, monodisperse, magnetic composite particles were prepared by heating micrometer‐sized, monodisperse, hollow polystyrene/polydivinylbenzene composite polymer particles at 200°C for 4 h (particles had been dipped in pentacarbonyliron) and then washed in 12 N HCl and water. The hollow polymer particles were produced by seeded polymerization by the dynamic swelling method that was proposed by authors. The magnetic composite particles contained Fe3O4, the content of which was 49% based on total weight, and were attracted easily in water by a 1650 G magnet. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 428–433, 2003
Review on the development of defect‐free and ultrathin‐skinned asymmetric membranes for gas separation through manipulation of phase inversion and rheological factors
Authors: Ismail Ahmad Fauzi , Yean Lai Ping
Published: February 2003

Development of high‐performance asymmetric membranes is a major breakthrough in membrane technology. A comprehensive study on original concepts and new advances in membrane formation process is necessary to generate defect‐free and ultrathin‐skinned asymmetric membranes with superior performance for gas separation process. Correlation of rheological factors with primary‐phase inversion process is a novel approach in membrane research that provides a potential platform to improve membrane performance. The former controls general morphology of membrane, whereas the latter further affects molecular orientation in membrane. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 442–451, 2003
Modification of aqueous acrylic–polyurethane via epoxy resin postcrosslinking
Authors: Shi Yuanchang , Wu Youshi , Zhu Zhiqian
Published: February 2003

An epoxy resin (E‐51)‐modified acrylic–polyurethane emulsion with triethylenetetramine (TETA) serving as the postcrosslinking agent was synthesized. The curing reaction between E‐51 and the curing agent TETA during the film‐forming course was monitored and identified by an infrared spectrophotometer. The stabilities of the single‐pack emulsion during the polymerization course as well as the storage stage were investigated. The effect of the epoxy resin was studied in terms of the dispersion size of the emulsion, the mechanical properties, as well as the swell in water and toluene of the cast film, The emulsion was shown to be stable when the epoxy content was below 20% based on the mass of the polyacrylate in the system. The tensile strength and the modulus and the water and toluene resistance were enhanced with increase of the epoxy resin. In contrast, the elongation at break was decreased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 470–475, 2003
Modeling of the transient viscosity for polymer melts after startup of shearing and elongational deformations
Authors: Seo Yongsok
Published: February 2003

In order to describe the transient stress growth for polymer melts, the empirical model proposed by Seo for the viscosity of steady‐state flow is combined with a phenomenological viscoelastic model of a differential type (the White–Metzner model) along the lines proposed by Souvaliotis and Beris. The relaxation time is taken as a function of the invariant of the stress tensor (hence that of the configuration tensor) rather than that of the rate of the deformation tensor. Numerical results show a good correlation with experimental data. The model predictions approach steady‐state values at long times after the startup. The nonlinear form of the model correlates very well with the experimental data over many decades of the deformation rate, both in shearing and elongational deformations. The proposed model is a simple one that can also describe the overshoot in the transient stress growth. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 510–515, 2003
Preparation and anticoagulant property of phosphorylcholine‐terminated o‐benzoylchitosan derivative
Authors: Zhu Aiping , Zhang Jun , Shen Jian
Published: February 2003

To improve the solubility in organic solvent of chitosan, o‐benzoylchitosan was synthesized by acylation with benzoyl chloride and then used in the reaction with 2‐chloro‐1,3,2‐dioxaphosphospholane (COP) to prepare phosphorylcholine‐terminated o‐benzoylchitosan (PC‐BCS). PC‐BCS had a structure with a phospholipid polar group characterized by FTIR and 1H NMR. PC‐BCS had been polysubstituted by a PC group, which made PC‐BCS viscous liquid. The anticoagulant properties of PC‐BCS were evaluated by means of blood‐clotting and platelet adhesion assay. The blood‐clotting assay indicated that PC‐BCS could prolong the blood‐clotting process. Platelet adhesion assay showed that PC‐BCS could effectively inhibit the platelet adhesion and activation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 489–493, 2003