bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary results on the sensitivity of atmospheric bending angles retrieved from COSMIC radio occultations to Doppler frequency shift and satellite velocity variationsThis article is one of a series of papers published in this Special Issue on the theme GEODESY.
Authors: Vergados Panagiotis , Pagiatakis Spiros D.
Published: September 2009

We describe and present preliminary results from an independent bending-angle algorithm implementation for the calculation of radiowave bending angles propagated from a Global Positioning System (GPS) to a Low Earth Orbiting (LEO) satellite. The algorithm utilizes raw atmospheric excess phases and satellite kinematics to determine Doppler frequency shifts of the GPS signals from which bending-angle profiles are derived. The intent is twofold: (a) perform a series of sensitivity studies to investigate the effect of Doppler frequency shift and satellite velocity variations on bending-angle profiles; and (b) examine and compare our results against the bending-angle profiles provided by the Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC) Data Analysis and Archive Centre (CDAAC). In this paper, we employ the same GPS observations as by CDAAC to analyze various occultation events in 2006, 2007, 2008, and 2009. Our principal finding is that radiowave bending angles exhibit an inversely proportional behaviour to orbital velocity variations while they change proportionally to the variations of Doppler frequency shift. Our studies also reveal that bending angles are more sensitive to orbital velocity than to Doppler frequency shift variations and show “wave-like” structures in the upper part of the atmosphere, unlike COSMIC-derived profiles. We discuss the differences between our derived bending-angle profiles and the COSMIC-derived profiles, emphasizing the advantages of our algorithm implementation.
Modeling topographical density for geoid determinationThis article is one of a series of papers published in this Special Issue on the themeGEODESY.
Authors: Kingdon Robert , Vaníček Petr , Santos Marcelo
Published: September 2009

In geoid computation, effects of real three-dimensional topographic masses on the Earth’s gravity field must be accurately quantified and, in the Stokes–Helmert scheme, replaced with effects of those masses condensed on the geoid. The most comprehensive modern schemes for evaluation of topographical effects account for terrain effects, use a spherical model of topography, and incorporate two-dimensionally varying models of topographical mass density. In this contribution, we employ a three-dimensionally varying model of topographical density. We use Newton’s integration to determine the direct topographical effect (DTE) on gravity and primary indirect topographical effect (PITE) on gravity potential. Lastly, we apply Stokes’ integration to calculate the DTE, PITE, and secondary indirect topographical effect (SITE) on geoidal height. We focus here on validation of our results and demonstration of our software’s capabilities. We present results for the simple geometrical shape of a disc under various rotations and for the anomalous density of lake waters. Effects on geoidal height for these simulations reach centimetre level, up to 2.2 cm in magnitude. For a simulation of the effects of neglected mass anomalies of the lakes, we find results reaching 0.8 cm in magnitude. We examine the behavior of our results as calculated using various step sizes for numerical integration and by comparing numerical results with analytical results for the specific case of a disc. These results suggest that the maximum percent error of our results is about 23.5% for the DTE on gravity and 7.6% for the PITE on gravity potential.
A late-glacial – Holocene palaeoecological record from Pye Lake on the eastern shore of Nova Scotia, CanadaGeological Survey of Canada Contribution 20080395.
Authors: Mott Robert J. , Walker Ian R. , Palmer Samantha L. , Lavoie Martin
Published: September 2009

Pollen and chironomid analyses and radiocarbon dating at Pye Lake on the eastern shore of Nova Scotia are used to outline the vegetation and climatic history of the area. The coast was deglaciated prior to ∼12 200 14C BP (14 300 cal BP), and herbaceous tundra vegetation invaded the area. Midge-inferred maximum summer surface-water temperatures in the lake ranged between 9 and 11 °C. Subsequent gradual warming to ∼18 °C by 10 800 14C BP (12 725 cal BP) favoured the migration of a variety of herbaceous and shrub taxa into the region. Rapid cooling to ∼10 °C saw vegetation revert to herbaceous tundra communities. This interval, related to the Younger Dryas cold interval of the North Atlantic and Europe, lasted until ∼10 000 14C BP (11 630 cal BP). The climate then warmed again to conditions similar to those that prevailed immediately before onset of Younger Dryas cooling. Further warming saw successive tree species migrate into the area until, by the mid-Holocene, the forests contained most of the taxa prevalent today. Since ∼3500 years ago, cooling of the climate has favoured conifer species over broad-leaved taxa. Agriculture and logging practices in the last 150 years have altered the forest composition, but pollen analysis of the most recent sediments cannot resolve these changes adequately.
Globally significant Early Permian crinoids from the Mount Mark Formation in Strathcona Provincial Park, Vancouver Island, British Columbia — preliminary analysis of a disappearing fauna
Authors: Webster G. D. , Haggart James W. , Saxifrage Carrie , Saxifrage Barry , Gronau Christian , Douglas Aileen
Published: September 2009

Strata of the Mount Mark Formation, Buttle Lake Group, exposed in the vicinity of Marble Peak in Strathcona Provincial Park, central Vancouver Island, contain a diverse Early Permian crinoid fauna. This is the first Permian fauna containing crowns and cups recognized from Wrangellia terrane. The fauna contains representatives of each of the major Paleozoic crinoid subclasses: Camerata, Disparida, and Cladida. Specimens were observed and photographed between 2004 and 2008. No specimens were collected in adherence to regulations of Stratcona Provincial Park. Preliminary identifications recognize several new genera and species within the fauna, but they are not named or described lacking specimens for repository. A minimum of 24 species are judged to be in the fauna, making it the second most diverse Permian fauna known from North America. Identified genera suggest a greater relationship to North American faunas than to Paleotethyan faunas, suggesting Wrangellia was closer to North America than to the Paleotethyan realm during Early Permian time. Exposures of the Mount Mark Formation in the vicinity of Marble Peak are undergoing karstification, and specimens are being lost under the harsh weathering conditions. Observations of individual specimens over a five-year interval found that morphologic details critical for identification are being lost at an alarming rate. It is recommended that sufficient specimens in the fauna should be collected as soon as possible for identification and analysis. These specimens should be preserved for future reference and could form an educational display in the Strathcona Provincial Park headquarters.
Effects of a triazole, uniconazol, on shoot elongation and root growth in loblolly pine
Authors: Barnes A. D. , Kelley W. D.
Published: September 2009

Uniconazol, applied in an aqueous solution to 3-year-old loblolly pine (Pinustaeda L.) at the soil–stem interface, decreased height growth by up to 55% after one growing season without phytotoxic effects. Results suggest that uniconazol may be useful in controlling height growth of seedlings and seed-orchard trees. The triazoles uniconazol, paclobutrazol, and BAS011106W were tested for effects on loblolly pine root growth. Root-applied uniconazol consistently increased root growth of 1-year-old seedlings. At 100 mg•L−1, uniconazol increased the number of new roots and survival by 47 and 19%, respectively. The increase in survival of uniconazol-treated seedlings was not statistically significant, but the tendency is encouraging.
Genetic parameters from a clonally replicated test of black spruce (Piceamariana)
Authors: Mullin T. J. , Morgenstern E. K. , Park Y. S. , Fowler D. P.
Published: September 2009

A clonally replicated field test of full-sib black spruce (Piceamariana (Mill.) B.S.P.) progeny was established at four locations in Nova Scotia. Estimated variance components for 5-year height growth and survival were interpreted according to an additive–dominance–epistasis genetic model and used to derive estimates of gain from various selection and deployment strategies. Five years after striking, 64% of the total genetic variance for height growth was due to additive variance. Virtually all of the remaining nonadditive variance was composed of epistatic variances; dominance variance was negligible. Narrow-sense heritability for 5-year height growth was low at 0.059. Substantial nonadditive variance contributed to a somewhat higher estimate of broad-sense heritability at 0.093. Family-mean heritabilities were much higher: 0.823 and 0.697 for half-sib and full-sib family means, respectively. Comparable heritabilities for survival were estimated with high standard errors and were considered unreliable. Results from this study indicate that clonal selection may provide large increases in genetic gain by capturing (i) genetic variance due to epistasis and (ii) a greater portion of the additive variance. Genetic gains for 5-year height growth in the order of 22.6% might be achieved using the best 1% of tested clones for operational planting. Clonal propagation may also be a preferred method to capture substantial genetic gain (about 11%) from selection at the family level, resulting in simplified management of breeding populations while reducing costs associated with conventional soil-based orchards.
Fuel moisture, forest type, and lightning-caused fire in Yellowstone National Park
Authors: Renkin Roy A. , Despain Don G.
Published: September 2009

The occurrence and behavior of lightning-caused fires in Yellowstone National Park were summarized for 17 years (1972–1988) during a prescribed natural fire program. Both ignition (occurrence) and spread (stand replacing fire activity) of fires were strongly influenced by fuel moisture and forest cover type. Fuel moisture estimates of 13% for large (>7.6 cm) dead and downed fuels indicated a threshold below which proportionately more fire starts and increased stand replacing fire activity were observed. During periods of suitable fuel moisture conditions, fire occurrence and activity were significantly greater than expected in old-growth, mixed-canopy lodgepole pine (Pinuscontorta Dougl. var. latifolia) and Engelmann spruce–subalpine fir (Piceaengelmannii Parry–Abieslasiocarpa (Hook.) Nutt.) forest types, and significantly less than expected in the successional lodgepole pine forest types. During periods of extended low fuel moisture conditions (drought), sustained high winds significantly reduced the influence of forest cover type on stand replacing fire activity. These extreme weather conditions were observed during the later stages of the 1988 fire season, and to a lesser extent, for a short duration during the 1981 fire season. The Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forest type typically supported little stand replacing fire activity, even though a preponderance of fire starts was observed.
Tissue-culture shoot and root system effects on field performance of loblolly pine
Authors: Anderson A.B. , Frampton Jr. L.J. , McKeand S.E. , Hodges J.F.
Published: September 2009

To study differences in growth between loblolly pine (Pinustaeda L.) tissue-culture plantlets and seedlings, shoot systems of plantlets and seedlings were grafted onto plantlet and seedling root systems. After three growing seasons, plantlet root systems accounted for 0.3 m of height growth loss and 1.0 cm of loss in basal diameter, while plantlet shoot systems accounted for 0.6 m of height growth loss and 1.4 cm of loss in basal diameter. The mature-appearing morphology of plantlet shoots was due to the shoot system of plantlets and not to the indirect effect of the plantlet root system.
Inheritance of temperature adaptation in intra- and inter-specific Populus crosses
Authors: Drew Allan P. , Chapman James A.
Published: September 2009

Populustrichocarpa Torr. & Gray from Alaska was crossed with the same species from a Montana population, and the resulting intraspecific hybrid was crossed with Populusdeltoides Bartr. ex Marsh, from Minnesota. Ramets from the five parents and hybrids were tested for the response of leaf conductance to temperature of the prior night. Leaf stomatal density and size were determined and net photosynthesis was measured between 15 and 40 °C for all clones. Alaska and Montana sources of P. trichocarpa and their hybrid showed mildly sensitive leaf conductance responses to 10 °C nights and comparable responses to 4 °C nights. The Alaska parent had an optimum rate of net photosynthesis at 20 °C, 10 °C lower than that of its hybrid, but the Montana parent's temperature response curve was less clearly defined. Although the P. trichocarpa hybrid was intermediate or similar to both parents in temperature adaptation, in stomatal density, size, and Q-ratio it was more similar to the Alaska parent. The P. deltoides parent and its interspecific hybrid exhibited a sensitive pattern of leaf conductance response to cool nights. The hybrid had a net photosynthetic temperature response curve that closely paralleled that of the P. deltoides parent, yet rates were lower, between 20 and 35 °C, in both compared with the P. trichocarpa parent. The interspecific hybrid more closely resembled the P. deltoides than the P. trichocarpa parent in overall temperature adaptation and had morning leaf conductance higher than that of both. Stomatal density and size were more unlike the P. deltoides than the P. trichocarpa parent, and the Q-ratio of the hybrid was intermediate to that of the parents.
Spread of Inonotustomentosus from infection centres in spruce forests in British Columbia
Authors: Lewis Katherine J. , Morrison Duncan J. , Hansen Everett M.
Published: September 2009

The path of infection in spruce (Piceaglauca × engelmannii Engelm.) by Inonotustomentosus (Fr.:Fr.) S. Teng, and disease development, were studied by excavating roots of trees in five plots situated at the edge of disease centres in 60- to 140-year-old stands. Root contacts resulted in infection only when ectotrophic or intrabark mycelium was present. The fungus directly penetrated the bark of roots less than 4 cm in diameter; bark disruptions, such as branch points for secondary roots, facilitated penetration to the cambium. Infection of the wood in 1- to 10-cm roots was often (54%) through infection of a feeder root. In roots less than 5 cm in diameter, mycelium in the bark preceded stain and decay in the root xylem by approximately 20 cm. In living roots larger than 5 cm in diameter, decay and stain was limited to long columns in the heartwood. Once one of these larger roots died, the fungus colonized its sapwood and bark, but did not grow distally in the root. Expression of crown symptoms was more closely related to root mortality than to the percentage of roots colonized.
The inheritance of mitochondrial DNA in Douglas-fir (Pseudotsugamenziesii)
Authors: Marshall Kimberly A. , Neale David B.
Published: September 2009

Restriction fragment length polymorphisms were used to determine the mode of inheritance of mitochondrial DNA in Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco). Total DNA of foliage from both of the parents and from progeny of a single Douglas-fir cross was digested with restriction enzymes and hybridized to a Zeamays L. mitochondrial DNA radiolabeled probe. Mitochondrial DNA was maternally inherited in this cross. Previous research showed paternal inheritance of chloroplast DNA in Douglas-fir, thus it appears that each of the three genomes of Douglas-fir is inherited differently.
Clonal selection in Cupressussempervirens: estimates of genetic parameters in juvenile growth
Authors: Giannini Raffaello , Raddi Sabrina
Published: September 2009

Fifty common cypress (Cupressussempervirens L.) clones were evaluated at two sites in central Italy over a period of 5 years (1983–1987) for height growth, degree of resistance to Seiridiumcardinale, and diameter growth (1986 and 1987 only). Phenotypic correlations between height and diameter were high, positive, and significant. No correlation was found between degree of resistance and growth traits. Analysis of variance indicated that clone, site, and site–clone interaction were the significant sources of variation for each year and trait. The trend of height variance components over years indicated that after the 1st year (planting year) site–clone interaction and experimental error remained more or less constant, while clonal effect increased and site effect decreased over years. The evaluation of the expected genetic gains from selection indicated that the costs of a site-specific breeding program, on sites similar to the two tested in this paper, were not economically justified.
SOLUTIONS OF THE DIVERGENCE AND ANALYSIS OF THE STOKES EQUATIONS IN PLANAR HÖLDER-α DOMAINS
Authors: DURÁN RICARDO G. , LÓPEZ GARCÍA FERNANDO
Published: September 2009

If Ω ⊂ ℝn is a bounded domain, the existence of solutions [Formula: see text] of div u = f for f ∈ L2(Ω) with vanishing mean value, is a basic result in the analysis of the Stokes equations. In particular, it allows to show the existence of a solution [Formula: see text], where u is the velocity and p the pressure.

It is known that the above-mentioned result holds when Ω is a Lipschitz domain and that it is not valid for arbitrary Hölder-α domains.

In this paper we prove that if Ω is a planar simply connected Hölder-α domain, there exist solutions of div u = f in appropriate weighted Sobolev spaces, where the weights are powers of the distance to the boundary. Moreover, we show that the powers of the distance in the results obtained are optimal.

For some particular domains with an external cusp, we apply our results to show the well-posedness of the Stokes equations in appropriate weighted Sobolev spaces obtaining as a consequence the existence of a solution [Formula: see text] for some r < 2 depending on the power of the cusp.
A MANGANESE OXIDE CONTAINED COATING FOR BIODEGRADABLE AZ31B MAGNESIUM ALLOY
Authors: YAN TINGTING , TAN LILI , XIONG DANGSHENG , ZHANG BINGCHUN , YANG KE
Published: September 2009

A manganese oxide contained coating was prepared on biodegradable AZ31B magnesium alloy to control the degradation of AZ31B and improve its biocompatibility. Morphology, composition, and corrosion resistance of the coating were studied. The SEM observations showed that the coating was approximately 4–6 μm in thickness with net-like microcracks. The XPS analysis indicated that the coating was mainly composed of MgO , Mg ( OH )2, MnO 2, Mn 2 O 3, and Mn 3 O 4. It was found that AZ31B with such coating showed better corrosion resistance in simulated blood plasma through electrochemical and immersion tests. The hemolytic assay indicated that the treated AZ31B had no hemolytic effect.
DETERMINATION OF ANISOTROPY OF CRYSTAL-MELT INTERFACIAL ENERGY FROM THE OBSERVED GRAIN BOUNDARY GROOVE SHAPES AT MULTIPLE ORIENTATIONS
Authors: EROL MUSTAFA , MARAŞLI NECMETTİN , BÖYÜK UĞUR
Published: September 2009

A specialized high-precision thermal gradient furnace with a rotating stage was developed for in situ observation of the equilibrated grain boundary groove shapes at multiple crystallographic orientations in transparent materials. Anisotropies of solid–liquid interfacial free energy for the distillated succinonitrile (SCN) and pivalic acid (PVA) are determined experimentally through direct observation of the equilibrated grain boundary grooves at the multiple crystallographic orientations stabilized within a controlled thermal gradient. The average anisotropies of solid–liquid interfacial energy for distillated SCN and PVA are found to be 0.42 and 3.12% from observed grain boundary groove shapes at multiple crystallographic orientations. Details related to the experimental apparatus and experimental procedures are given.
CHARACTERIZATION OF PRUSSIAN BLUE NANOPARTICLES PREPARED BY REVERSE MICELLE AND ELECTROCHEMICAL STUDY OF THEIR ASSEMBLY
Authors: QIU JINGXIA , LIU JIWEI , SUN KAI , MIAO YUQING
Published: September 2009

Well-dispersed Prussian blue (PB) nanoparticles were successfully prepared by reverse micelle. This method is based on one-step rapid formation in different sizes of nano-pool with water/oil system, which leads to a homogeneous distribution of PB nanoparticles. Scanning electronic microscopy, UV–vis, and Fourier infrared spectra give supportive evidence of PB nanoparticles. Electrochemical study shows that PB nanoparticles are modified onto cysteine-assembled Au electrodes and exhibit high efficiency of electron transfer.
THE EFFECT OF CRYSTAL FORM OF N-DOPED TITANIUM DIOXIDE ON VISIBLE-LIGHT PHOTOCATALYTIC ACTIVITY
Authors: ZHANG JIWEI , ZHANG JINGWEI , JIN ZHENSHENG , WU ZHISHEN , ZHANG ZHIJUN
Published: September 2009

TiO 2 samples with different crystal forms were treated in flowing NH 3 at elevated temperatures to fabricate N -doped TiO 2 photocatalysts with different crystal forms. The resulting N -doped TiO 2 photocatalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffusion reflectance spectrometry, and X-ray photoelectron spectroscopy. The visible-light photocatalytic activity of the catalysts was evaluated by measuring the photocatalyzed removal rate of propylene. Results indicate that the visible-light activity of N -doped TiO 2 photocatalysts is highly dependent on the crystal form. Namely, N -doped anatase TiO 2 has the highest visible-light activity, while the visible-light activity of N -doped TiO 2 photocatalysts decreases with decreasing content of anatase phase and increasing content of rutile phase. In addition N -doped rutile TiO 2 has no visible-light photocatalytic activity.
FACILE CYCLOADDITION OF TRANSITION METAL OXIDES ONTO THE SIDEWALL OF BORON-DOPED FULLERENE
Authors: TANG ZI-RONG
Published: September 2009

The viability of facile oxidation and cycloaddition of fullerene C 60 with ruthenium tetraoxide ( RuO 4) has been confirmed by means of density functional theory calculations. Owing to the powerful capability of RuO 4 as an oxidant, the addition process has been found to occur readily in the absence of organic base as a catalyst, which is in remarkable contrast to the base-catalyzed osmylation of C 60 with osmium tetraoxide ( OsO 4). Significantly, we have found that boron can be employed as an effective promoter for enhancing the cycloaddition and complexation of transition metal oxides, e.g. RuO 4 and OsO 4, with C 60, in which the base is not needed at all. Our results suggest that boron doping into the lattice of fullerenes and carbon nanotubes would provide a well-defined approach for anchoring transition metal oxides.
STRUCTURE AND FERROELECTRIC PROPERTIES OF Bi0.95La0.05FeO3 FILM ON INDIUM TIN OXIDE (ITO)/GLASS SUBSTRATE
Authors: GAO QIANG , ZHENG WEI
Published: September 2009

Bi 0.95 La 0.05 FeO 3( BLFO x=0.05) film was fabricated on indium tin oxide/glass substrate using a metal organic decomposition method. No secondary phase can be observed in the well crystallized and predominantly (110)-oriented BLFO x=0.05 film. Well-saturated P - E hysteresis loops with the remanent polarization of 60.7 μC/cm2 can be obtained in BLFO x=0.05 film due to the low leakage currents as well as the preferred orientation of the (110) peak. The content of oxygen vacancies in the film is considered to be the dominant factor affecting the asymmetry ferroelectric properties and leakage currents.
SYNTHESIS OF MANGANESE OXIDE NANOSTRUCTURES ON CARBON PAPER FOR SUPERCAPACITOR APPLICATIONS
Authors: MASTRO M. A. , EDDY C. R. , KUB F. , PARK J. , CHO J. , KIM J.
Published: September 2009

A simple hydrothermal growth process was developed to deposit conformal manganese oxide nanospheres with a diameter of 10 to 20 nm on mesoporous carbon paper. The coating of nanospheres increased the cyclic-voltammogramic response of carbon paper by a factor of 5 with a slight dependence on the scan rate. For comparison, a related chemistry was also developed to fabricate a dense packing of manganese oxide nanorods with a diameter of 20 to 50 nm and a length of approximately 500 nm. The nanorods also increased the cyclic-voltammogramic response of carbon paper but only by a factor of approximately 3.
A NOVEL CATALYST FOR REDUCTIVE DECHLORINATION OF CHLOROBENZENE IN SUBCRITICAL WATER: BIFUNCTIONAL Fe/ZrO2
Authors: WEI GUANG-TAO , WEI CHAO-HAI , HE FENG-MEI , WU CHAO-FEI
Published: September 2009

Bifunctional Fe / ZrO 2 was prepared by mechanical mixing method, and its bifunctional effect on reductive dechlorination of chlorobenzene in subcritical water was studied. Dechlorination efficiency increased with increasing iron content in catalyst and catalyst amount. Dechlorination efficiency slowed when the iron content in catalyst reached 30%; bifunctional catalyst of Fe / ZrO 2 was more efficient in dechlorination of chlorobenzene than Fe alone. Catalyst of Fe (30%)/ ZrO 2 was characterized by means of X-ray diffraction (XRD), H 2 temperature programmed desorption ( H 2-TPD), and N 2 adsorption. The possible mechanism of dechlorination in subcritical water by this bifunctional catalyst was proposed. H + produced in the water dissociation formed the highly reactive spillover hydrogen on the surface of catalyst, and then reacted with chlorobenzene adsorbed on the catalyst surface by ZrO 2 to form benzene and chloride ions.
POLARIZATION PROPERTIES OF FERROELECTRIC THIN FILMS UNDER DIFFERENT BOUNDARY CONDITIONS
Authors: CHEN HUI , CHENG TAIMIN , CHEN SIQUN , GANG TIECHEN
Published: September 2009

By taking into account two types of boundary conditions (BC), free boundary condition (FBC) and zero boundary condition (ZBC), an improved transverse Ising model with the consideration of surface transition layers (STL) is used to describe the polarization properties of ferroelectric thin films in the framework of the mean field approximation. Functions representing the intra-layer and inter-layer couplings are introduced to characterize the BC and STL, which reflect the structure variation of film surface. Comparing the results obtained by employing FBC and ZBC, some effects of BC are derived in the model, which demonstrated that the BC play important roles on the properties of ferroelectric thin films. It is shown that the effect of ZBC can extend to deeper film than that of FBC. When different BC are adopted, competition between the fields (depolarization field and transverse field) and BC induces some different and interesting phenomena. Some theoretical results in this paper are found to be in reasonable accordance with experimental data and have some application importance.
TRIBOLOGICAL AND REFRACTORY PROPERTIES OF TiAl3 INTERMETALLIC ALLOY
Authors: KRÁL JOZEF , FERDINANDY MILAN , KOTTFER DANIEL , MAŇKOVÁ ILDIKÓ , CENIGA LADISLAV
Published: September 2009

Substrates of Ti -based coatings were investigated regarding wear resistance and refractoriness. Substrates with and without the TiAl 3 coating formed by the ion plating method with evaporation of Al are considered. Additionally, the paper briefly presents principles of kinetics of the formation of the TiAl 3 coating.
ADSORPTION OFLiONMo(110) SURFACE: A FIRST-PRINCIPLES STUDY
Authors: ZHOU Y. G. , ZU X. T. , NIE J. L. , XIAO H. Y.
Published: September 2009

Periodic, self-consistent, density functional theory calculations have been performed to investigate Li adsorption on Mo (110) surface. It turns out that the long-bridge site is the most stable site and the Li – Mo surface alloy forms easily at high coverage with the substitution of Mo by Li atoms in the outermost layer. Work function analysis showed that the work function decreases dramatically as the coverage from 0 to 0.5 ML, and finally increases again at the coverage of 1 ML, which agrees well with the experimental finding of Kroger et al. (Surf. Sci.449 (2000) 227–235). Vibrational properties, diffusion barrier of Li along the Mo (110) surface, and the energy of formation of the surface have also been investigated for Li adsorption at various coverages.
GLOBAL STABILITY IN A TUBERCULOSIS MODEL INCORPORATING TWO LATENT PERIODS
Authors: LIU LUJU
Published: September 2009

A tuberculosis (TB) model with two latent periods, short-term latent period (E1) and long-term latent period (E2), and fast and slow progressions is analyzed. The stability of the unique endemic equilibrium of the model is proved. It turns out that the disease-free equilibrium is globally asymptotically stable if the basic reproduction number R0 ≤ 1, and the endemic equilibrium is globally asymptotically stable if R0 > 1.
NOVEL EXPONENTIAL STABILITY CONDITIONS FOR A CLASS OF INTERVAL PROJECTION NEURAL NETWORKS
Authors: LIU ZIXIN , LÜ SHU , ZHONG SHOUMING
Published: September 2009

In this paper, a class of interval projection neural networks for solving quadratic programming problems are investigated. By using Gronwall inequality and constructing appropriate Lyapunov functionals, several novel conditions are derived to guarantee the exponential stability of the equilibrium point. Compared with previous results, the conclusions obtained here are suitable not only to convex quadratic programming problems but also to degenerate quadratic programming problems, and the conditions are more weaker than the earlier results reported in the literature. In addition, one numerical example is discussed to illustrate the validity of the main results.
A NEW RESULT ON THE PERIODIC SOLUTIONS FOR DISCRETE PERIODIC n-SPECIES COMPETITION MODELS WITH DELAYS
Authors: ZHANG YU , TENG ZHIDONG , GAO SHUJING
Published: September 2009

A discrete time periodic n-species Lotka–Volterra type competitive model with delays is investigated. By using Gaines and Mawhin's continuation theorem based on the coincidence degree theory, a new sufficient condition on the existence of positive periodic solutions of the model is established.
HEAT TRANSFER IN A SLIP FLOW OF PERISTALTIC TRANSPORT OF A MAGNETO-NEWTONIAN FLUID THROUGH A POROUS MEDIUM
Authors: SOBH AYMAN MAHMOUD
Published: September 2009

In this paper, we study the interaction of peristalsis with heat transfer for the flow of a viscous fluid through a porous medium in uniform and nonuniform channels. The flow is subjected to constant transverse magnetic field. Long wavelength approximation (that is, the wavelength of the peristaltic wave is large compared with the radius of the channel) is used to solve the governing system. Closed form expressions are derived for the pressure–flow relationship, temperature, and heat transfer coefficient. The effects of various physical parameters are discussed through graphs.
STABILITY AND HOPF BIFURCATION OF A DELAY DIFFERENTIAL SYSTEM IN MICROBIAL CONTINUOUS CULTURE
Authors: LI XIAOFANG , QU RONGNING , FENG ENMIN
Published: September 2009

Introducing discrete time delay into the model for producing 1, 3-propanediol by microbial continuous fermentation, the stability and Hopf bifurcation of a delay differential system for microorganisms in continuous culture are considered in this paper, including the changing regularity of bifurcation value and oscillating period. Algebraic criteria for absolute stability, as well as the transversality condition for Hopf bifurcation of this kind system are obtained. Explicit algorithm for determining the direction of Hopf bifurcation and the stability of periodic solution is derived, using the theory of normal form and center manifold. Finally, numerical simulations show the effectiveness of our results. The pictures of periodic solutions and phase planes with specified parameters suggest that our results can qualitatively describe oscillatory phenomena occurring in experiments.
Non-Aqueous/Dry Cleaning Technology without Causing Damage to Fragile Nano-Structures
Authors: Hattori Takeshi
Published: September 2009

With semiconductor-device geometry shrinking and becoming more complex, conventional aqueous cleaning/drying tends to collapse free-standing MEMS and high-aspect-ratio fragile LSI structures due to the high surface tension of aqueous chemicals and water. The use of physical cleaning aids such as megasonics with dilute chemistry or high-pressure atomizing jet sprays can also cause damage to nano-structures. The process window for damage-free cleaning is also becoming narrower as device geometry shrinks. This makes the development of new damage-free cleaning methods a high priority. In this paper, various alternative damage-free non-aqueous/dry cleaning techniques are described and discussed including low pressure, elevated temperature HF vapor cleaning, cryogenic aerosol cleaning, supercritical CO2 cleaning, and pinpoint dry cleaning that employs lasers, nano-probes, or nano-tweezers. There will be more research challenges and opportunities in these environmentally-benign damage-free cleaning technologies in the future.
New Wet Process Strategies for Reduced La2O3 and MgO2 High-k Cap-dielectric Loss
Authors: Wada Masayuki , Vos Rita , Claes Martine , Schram Tom , Snow Jim , Mertens Paul , Eitoku Atsuro
Published: September 2009

Lanthanum oxide (LaxOy) and magnesium oxide (MgxOy) high-k cap-dielectrics have been used to modulate the effective work function for high-k/metal gate CMOS devices. The use of DIW during wet processing leads to unacceptable material loss due to the high solubility of materials. In this work, new rinsing procedures with pH-controlled and solvent-based solutions were evaluated in order to avoid material loss. It is validated that both pH-controlled (> pH 10) and solvent-based solutions achieve less than 1 Aå of La2O3 loss and solvent-based solutions can well be used on MgO2, providing less than 1 Aå loss. Furthermore, no adverse affects, such as an increase in particle or surface roughness, were observed by applying the new rinsing procedures.
Study of CMOS-compatible Copper Etching for Organic Coating
Authors: Lambert Magali , Rostam-Khani Patrick , Ten Veen Jacoline , Van Nimwegen Leon , Frederix Filip
Published: September 2009

Biosensors based on advanced CMOS processing have copper surfaces. These copper surfaces have to be functionalized with biological receptors to allow bio-sensing. The cleaning of the CMOS copper interface is therefore a critical step to allow good attachment and formation of self-assembled monolayers of thiol-molecules. Different cleaning procedures were tested and evaluated in terms of roughness (by atomic force microscopy AFM), oxide formation and contamination (by time of flight - secondary ion mass spectrometry TOF-SIMS). The quality of the deposited self-assembled monolayer was assessed by x-ray photoelectron spectroscopy (XPS) and by grazing-angle Fourier transform infrared spectroscopy (GA-FTIR). The optimal cleaning treatment for the formation of a well-ordered octadecanethiol monolayer was obtained with an etching of 5 minutes in 3.7% HCl.
Influence of UV Irradiation on the Removal of Post-etch Photoresist in Porous Low-k Dielectric Patterning
Authors: Kesters Els , Le Quoc Toan , Lux Marcel , Onandia Laura , Baerts Christina , Vereecke Guy
Published: September 2009

All-wet processes are gaining a renewed interest for the removal of photoresist (PR) after plasma etching in back-end of line (BEOL) applications. However, degradation of DUV PR by the etch plasma results in a modified top layer of the PR that is cross-linked (so-called crust) and that is no longer soluble in pure organic solvents. This study investigates the modification of a 193-nm post-etch PR by UV irradiation. We show that a 254 nm mercury vapor UV lamp and a 248 nm UV excimer laser can cause scissioning of C-C bonds in the PR main chain, thereby improving the dissolution of the PR in organic solvent.
Effect of Radical Scavenger and UV Irradiation on Removal of Photoresist and BARC using Water/Ozone in Cu/Low-k Interconnect
Authors: Le Quoc Toan , Lux Marcel , Kesters Els , Prager Lutz , Vereecke Guy
Published: September 2009

This study focused on the removal of post-etch photoresist (PR) and bottom anti-reflection coating (BARC) layers using O3 dissolved in H2O at 60 {degree sign}C. A complete removal of the PR layer was achieved with a short rinse in propylene carbonate (PC). However, the k-value of the film as determined using Hg-probe showed an increase of about 0.3 due to the wet process at 60 {degree sign}C for 5 min, and the BARC layer remained on the substrate. Using acetic acid (HAc) 0.5 M, a radical scavenger, as additive resulted in a small reduction in k-value of about 0.2 with respect to the sample processed in the same solution without HAc. Within the range of HAc concentration of 0.01-0.5 M, there was no clear trend and no significant effect in terms of PR removal as a function of HAc concentration, indicating a direct O3 attack of PR. The issue of BARC removal was addressed using UV treatment at 222 nm wavelength.
SAM Modification of CMP Conditioner for the Prevention of Particle Adhesion
Authors: Kwon Tae-Young , Kang Young-Jae , Kim In-Kwon , Kim Dong-Chan , Kim Jeong , Chun Jong-Sun , Park Mun-Seak , Park Jin-Goo
Published: September 2009

Pad conditioning is a necessary step during CMP (Chemical Mechanical Planarization) process to maintain the performance such as uniform material removal rate and its uniformity. The Ni electroplated diamond conditioner has been used and its surface could be easily contaminated by slurry particles and by-products during conditioning. We have proposed the hydrophobic SAM (self assembled monolayer) modification to CMP conditioner to reduce residue contamination. After CMP conditioning process, the contamination was reduced highly on the surface of the conditioner when it was coated with hydrophobic film.
Screening and Evaluation of Different Wet Cleaning Solutions for Post Etch Residue Removal in BEOL Applications
Authors: Suhard Samuel , Claes Martine , Loh James , Vereecke Guy , Pantouvaki Mariana , Demuynck Steven , Vereecke Bart , Beyer Gerarld
Published: September 2009

Two types of wet cleaning solutions were screened for post etch residue removal in back end of line applications: aqueous acid chemistries and organic solvents. Their compatibility with plasma damaged low-k materials and their polymer removal efficiency were checked on blanket low-k layers and single damascene layers, respectively. Aqueous acid chemistries under study showed either to be compatible with plasma damaged low k material but had poor polymer removal efficiency, or showed good polymer removal but also removal of the plasma damaged low-k. A correlation between the damaged low-k and the amount of etching additive in aqueous acid chemistry could be established. Initial tests with organic solvents demonstrated that they were compatible with the damage low-k layer. Concerning polymer removal, some partial dissolution of polymers was observed for the first time. Furthermore, the cleaning performance of organic solvents, and hence the electrical performance, can be improved by applying megasonic power during the clean process.
Dilute HF Solutions for Copper Cleaning during BEOL Processes: Effect of Aeration on Selectivity and Copper Corrosion
Authors: Padmanabhan Ramalekshmi Thanu Dinesh , Venkataraman Nandini , Raghavan Srini , Mahdavi Omid
Published: September 2009

Effectiveness of dilute HF based formulations in selectively removing copper oxide (CuOX) films with respect to copper and dielectric films has been investigated. Key solution variables studied include HF concentration, dissolved oxygen level and pH. Improved CuOX/Cu selectivity has been achieved under deaerated conditions. Deaerated solution containing 1000:1 HF (pH3) provides CuOX/Cu selectivity of ~50:1 and CuOX/low-k dielectric (Carbon Doped Oxide) selectivity of ~15:1. Conditions under which copper can be passivated during cleaning in dilute HF have been explored using electrochemical polarization studies and Electrochemical Quartz Crystal Microbalance (EQCM).
Cleaning Process in Single Wafer Tool: Impact of Dispersion Phenomena on Rinsing Time
Authors: Mallet Antoine , Prat Marc , Broussous Lucile , Schmitz Philippe
Published: September 2009

Silicon wafers fabrication involves many wet processes in which liquids are distributed across the wafer surface. In single wafer tools, the fluid dispense is crucial and determines how homogeneous the cleaning process will be achieved. The fluid dynamics and chemical transport in the rinsing flow are studied and it is shown that dispersion phenomena in the radial direction due to non homogeneous velocities across the fluid layer have to be taken into account in the general analysis of rinsing time.
Yield Qualification of All Wet Photoresist Stripping for CMOS Well Loop Implant Masks in 300mm High Volume Manufacturing
Authors: Nan Ron , Lee Freda , Hung Jey , Chu James M. , Yuan Jack , Yang David , Butterbauth Jeffery W.
Published: September 2009

A methodology to develop and qualify post ion implant photoresist all wet stripping process in volume manufacturing environment is presented. The qualification result show equivalent physical defect control and greater than 99.9% yield performance similarity compared to the current manufacturing baseline process. The estimated benefit from adoption of all wet photoresist stripping includes greater than 60% process cycle time reduction and greater than 3 times improvement in cleanroom space utilization for productivity.
Lossless Solvent-based Extension Implant Strip
Authors: Vos Rita , Mannaert Geert , Halder Sandip , Wada Masayuki , Sonnemans Roger , Tsvetanova Diana , Valckx Nick , Vanstreels Kris , Conard Thierry , Mertens Paul
Published: September 2009

A new approach is presented for resist strip after high-dose implantation of ultra-shallow extensions with minimal loss in the S/D area. For our work, solvents are selected in combination with physical force to remove the resist because of their excellent selectivity towards the sensitive USJ implanted substrates. To enable a more gentle physically enhanced strip of the crusted resist with less risk for damage and less residues left, a short oxidizing pre- and/or post-treatment has to be introduced. Wet O3-based cleans have limited efficiency while UV/O3-exposure and particularly a short plasma step are found to be beneficial. The effect of such an oxidizing treatment on the crusted resist and its removal is presented as well as the effect on highly doped substrates. It is shown that especially after NMOS implantation, a short oxidizing step results in better dopant retention during activation anneal due to the grown oxide.
Characterization of 248nm Deep Ultraviolet (DUV) Photoresist after Ion Implantation
Authors: Tsvetanova Diana , Vos Rita , Vereecke Guy , Clemente Francesca , Vanstreels Kris , Conard Thierry , Franquet Alexis , Parac-Vogt Tatiana N. , Mertens Paul , Heyns Marc M.
Published: September 2009

The elemental and structural changes of 248nm DUV photoresist induced by arsenic implantation with high dose and different acceleration energies were studied. For this purpose different analytical techniques were combined. An investigation of the capabilities of the Micro Raman Spectroscopy for analysis of ion implanted photoresist (II-PR) revealed that the method is unreliable for the characterization of II-PR since it induces a modification of the top crust layer. Moreover, alternative methods were used for characterization of the crust. The crust structure was indentified as cross-linked PR by Solid State Nuclear Magnetic Resonance. No experimental evidence for presence of amorphous carbon was found. Furthermore, the elemental composition and mechanical properties of the crust as a function of the implant energy were discussed as a measure for the cross-linking density. Finally, the dopant role in the cross-link process was considered.
Photo-etching of Silicon by N-Fluoropyridinium Salt
Authors: Goto Shigeharu , Tsukamoto Kentaro , Kawase Tatsuya , Ajari Noritaka , Nagai Takabumi , Adachi Kenji , Uchikoshi Junichi , Morita Mizuho
Published: September 2009

Silicon is etched by applying N-fluoropyridinium salts to its surface and exposing the surface to light. Etching depth increases with exposure time. The H-terminated hydrophobic Si is easier to be etched than the OH-terminated hydrophilic Si. SiF4 is produced by the photo-etching.
Investigation of Physical Cleaning Process Window by Atomic Force Microscope
Authors: Kim Tae-Gon , Wostyn Kurt , Bearda Twan , Park Jin-Goo , Mertens Paul , Heyns Marc M.
Published: September 2009

The pattern damage-free process window of physical cleaning was investigated by measuring the pattern collapse and particle removal forces using atomic force microscope with a quantitative lateral force calibration method. The pattern collapse forces of amorphous Si (a-Si) with 20 nm in width and 100 nm in height and TiN/black diamond (BD) II/SiCN-SiCO with 80 nm width and 210 nm height on SiO2/Si-substrates were measured. The particle removal forces of silica and PSL with 100, 300, and 500 nm diameters were measured on ozone last Si surface. The damage free cleaning process windows certainly were measured to be 600 and 3000 nN for a-Si and BDII, respectively.
Damage Cluster Analysis of Patterned Wafers during Solvent Spray Cleaning
Authors: Halder Sandip , Wostyn Kurt L. , Andreas Michael , Wada Masayuki , Brems Steven , Bearda Twan , Pacco Antoine , Kenis Karine , Vos Rita , Mertens Paul
Published: September 2009

As device structures become smaller they also become more fragile. With the incorporation of metal-high-k layers and shallower implants galvanic corrosion and substrate loss requirements are becoming an important issue. Aqueous chemistries are ceasing to be an option and new solvent cleans are continuously being experimented with. Physical force assisted solvent cleans are increasingly being considered for the removal of particles and resist residues. Whenever a physical force assisted clean is used damage becomes a major concern. In this work the effect of different solvents spray cleans on defect densities over the wafer will be discussed. The damage sites were further analyzed for clusters. The number of defects per cluster for the different solvents was also analyzed. Finally, the cluster size distribution was evaluated for the different solvents.
Impact of Steam-Water Mixed Spray on Silicon and Metal Surfaces
Authors: Mashiko Takashi , Hayashida Atsushi , Yamada Yoshimi , Sanada Toshiyuki , Watanabe Masao
Published: September 2009

Performance of photoresist stripping using steam-water mixed spray is quantitatively investigated with water flow rate as the operating parameter. The most striking and the most important finding is that air-water mixed spray turns out hardly effective. This result shows the peculiar superiority of the proposed technique. As we found that the prominently excessive long time of spraying of steam-water mixture on metal surface results in surface abrasion, this result strongly suggests that both the resist strippping and metal surface abrasion are dominated by essentially the same mechanism. We speculate that our proposing technique is categorized in the physical force cleaning. We discuss the role of the water flow rate in this cleaning technique and the validity of the assumption of physical force cleaning.