bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of corridors on the movement behavior of the jumping spider Phidippus princeps (Araneae, Salticidae)
Authors: Baker L.
Published: September 2007

Corridors are a common conservation strategy intended to increase the spatial connectivity among isolated habitat patches. Corridors, however, are not always effective. This study demonstrates that corridors increase movement to new patches for the jumping spider Phidippus princeps (Peckham and Peckham, 1883) (Araneae, Salticidae), a visually oriented predator. I assigned spiders to one of three microlandscape treatments, created in an old field dominated by alsike clover ( Trifolium hybridum L.) and alfalfa ( Medicago sativa L.), in which patches were connected to (i) vegetated corridors and bare pathways, (ii) only vegetated corridors, and (iii) only bare pathways. The movement of P. princeps was effectively directed by corridors. When given a choice of paths, spiders invariably chose vegetated corridors over bare pathways to emigrate from and to immigrate to new patches. Spiders rarely moved between patches when only bare pathways were available. In the absence of corridors, P. princeps did not risk open ground to move to new habitat even though conspecific density was high. The corridors facilitated the interpatch movement of P. princeps, suggesting that P. princeps is restricted in its habitat use. Thus, a higher degree of spatial connectivity is likely to increase the exchange of individuals for species that are restricted in their movements by unsuitable habitat.
A NEW TYPE OF CAVITATION DAMAGE TRIGGERED BY BOUNDARY-LAYER TURBULENT PRODUCTION
Authors: LI S. C. , LIU S. H. , WU Y. L.
Published: September 2007

A new type of cavitation damage has been observed on the turbines installed at the Three Gorges Power Station despite no cavitation detected during model tests. Metallurgical and fluid dynamic analysis suggests that this cavitation is triggered by boundary-layer turbulent production; the damaged (roughened) spot in turn triggers subsequent cavitation (damage) immediately down stream. This forms a sustainable dynamic process, resulting in long and equal-width streamwise damage-strips with spanwise regularity reflecting the spanwise stochastic characteristics of turbulent production. Owing to the heat effect of cavitation, intergranular corrosion takes place through sensitization process, leaving the damaged surface with a corrosion appearance. Also, bluing presents at the damaged tails, owing to the nature of low-intensity damage. Extremely large turbines are much more susceptible to this type of cavitation (damage) owing to the similarity laws currently employed for turbine development not concerning the freestream turbulence and the boundary-layer dynamics.
MICROSTRUCTURE OF FeCo–Cu NANOGRANULAR FILMS WITH GIANT MAGNETORESISTANCE
Authors: WANG CHANGZHENG , ZHANG PEIMING , ZHANG YIQING , XIAO XIAOGUANG , RONG YONGHUA , TSU H. Y.
Published: September 2007

A series of ( Fe 50 Co 50)x Cu 1-x granular films were prepared using a magnetron-controlled sputtering system. The microstructure and giant magnetoresistance of FeCo–Cu films deposited at room temperature and then annealed at various temperatures were investigated through X-ray diffraction, transmission electron microscope and conventional four-probes method under room temperature, respectively. The results revealed that FeCo–Cu films consisted of fine FeCo granules uniformly dispersed in the Cu matrix and formed fcc structure. Meanwhile the Cu (111) interplaner lattice spacing decreased with increasing magnetic volume fraction (x) due to the presence of the metal coherent interface strains and FeCo–Cu alloying. Upon varying the magnetic volume fraction (x), the giant magnetoresistance of as-deposited FeCo–Cu films reached a maximum of about 0.7% at the volume fraction of 31%, corresponding to the fact that the giant magnetoresistance has a non-monotonic relationship with the granule size. In addition, the relationship between the full width at half maximum (FWHM) or the sensitivity of the giant magnetoresistance and the volume fraction are discussed in detail.
RESEARCH ON BROWNIAN MOVEMENT BASED ON GENERALIZED MANDELBROT–JULIA SETS FROM A CLASS COMPLEX MAPPING SYSTEM
Authors: WANG XINGYUAN , LIU WEI , YU XUEJING
Published: September 2007

This article analyzes the typical Langevin problem, i.e. the dynamics of a charged particle under the circularly successive influence of several simple impulse functions moving in a double-well potential and a time-dependent magnetic field. Using the stroboscopic sampling, by selecting an appropriate magnetic intensity and time interval, we reduce the Langevin equation to a class complex mapping system. Through an experimental mathematical method, the authors study the structures of generalized M–J (Mandelbrot–Julia) sets generated by the complex mapping system, and expatiate the theory of Brownian movement. The authors find that:.

(1) This paper extends Shirriff constructed M sets by combining two simple complex mappings;.

(2) The fractal structure of the generalized M–J sets may visually depict the rule of Brownian movement, and the infinite overlapping embedment self-similar structure reflects the complexity of Brownian movement;.

(3) Whether the selected time interval is significant or not determines the continuity of the fractal structure for the generalized M–J sets;.

(4) The changing rule of particle velocity depends on the different choices of the principal range of phase angle;.

(5) If we change the choices of the magnetic intensity and time interval, for example, we choose a randomly fluctuating magnetic field, the generalized J sets may emerge the interior-filling structure feature, i.e. "explosion" phenomena appear in the closure of the unstable periodic orbits of the particle in the velocity space.
EFFECT OF MICROWAVE IRRADIATION ON COPPER NANOWIRES SYNTHESIZED BY ELECTROCHEMICAL DEPOSITION THROUGH ION TRACK MEMBRANES AS TEMPLATES
Authors: KUMAR SANJEEV , CHAKARVARTI S. K.
Published: September 2007

15 μm thick polycarbonate films were irradiated with Ni ions (11.64 MeV/n) having fluence of the order of 106 ions/cm2. Irradiated foils were etched chemically in 6N NaOH solution at 50°C for 12 minutes to obtain the cylindrical pores having average diameter of 100 nm. Cylindrical pores in these membranes have been used as templates for the synthesis of copper nanowires. A two-electrode electrochemical cell was used for copper electrodeposition in porous polycarbonate templates from acidic copper sulphate solution at 29 ± 1° C . The morphology of copper nanowires were studied by means of scanning electron microscopy (SEM). Effects of microwave treatment on these nanowires were also studied.
LASER ASSISTED SURFACE MODIFICATION OF Ti–6Al–4V FOR BIOIMPLANT APPLICATION
Authors: BISWAS A. , CHATTERJEE U. K. , LI LIN , MANNA I. , DUTTA MAJUMDAR J.
Published: September 2007

The present study aims at enhancing the wear resistance of Ti –6 Al –4 V by laser surface nitriding. Laser surface treatment has been carried out by melting of the sand blasted Ti –6 Al –4 V substrate using a high power continuous wave Diode laser with nitrogen as shrouding environment (at a gas flow rate of 51/min). Laser surface nitriding led to formation of dendrites of titanium nitrides. The microhardness is improved to a maximum of 900–950 VHN (Vickers hardness number) in laser surface nitriding as compared to 260 VHN of the as-received substrate. Surface nitriding increased primary potential for pit formation (Epp1) as compared to Ti –6 Al –4 V . Biocompatibility behavior showed a better cell viability due to surface nitriding as compared to the as-received Ti –6 Al –4 V .
A SIMPLE METHOD FOR THE SYNTHESIS OF TUNGSTEN TRIOXIDE NANORODS ARRAY WITHOUT CATALYST
Authors: ZHANG JULAN , ZHANG GENGMIN , GUO DENGZHU , WU YUE , XI ZHONGHE
Published: September 2007

Arrays of tungsten oxide nanorods, approximately 500 nm in diameter and 10 μm in length, have been grown in a catalyst-free reaction by heating tungsten wires at 900°C in a humid argon flow. They were systematically characterized using different surface analysis techniques. The chemical composition was determined to be stable stoichiometric binary oxide monoclinic tungsten trioxide. Water vapor was found to be crucial for the formation of these WO 3 nanorods. The vapor–solid (VS) process was introduced to discuss the growth mechanism.
LOW-TEMPERATURE CATALYTIC PERFORMANCE OF NANOSTRUCTURED Ti–Ni–O PREPARED BY MODIFIED SOL-GEL METHOD
Authors: WU YING , WU TINGHUA , HE YIMING , WENG WEIZHENG , WAN HUILIN
Published: September 2007

Nanosized Ti – Ni – O catalysts prepared by a modified sol–gel method had been investigated in the oxidative dehydrogenation of ethane and propane to the corresponding alkene. The best yield is obtained over the 9.1 wt% Ti – Ni – O catalyst. The results of catalyst characterization indicated that there is strong interaction between TiO 2 and NiO . It is observed that a decline in temperature for low-temperature oxygen desorption and an augmentation in reduction difficulty of the catalysts would result in poor activity and enhanced alkene selectivity, respectively, over the Ti – Ni – O catalysts in the oxidative dehydrogenation reactions.
FORMATION AND FIELD EMISSION CHARACTERISTICS OF AMORPHOUS AND CRYSTALLINE Si NANOARRAYS
Authors: XU J. , LI W. , ZHOU J. , XU L. , CEN Z. H. , CHEN K. J. , SONG F. Q. , WAN J. G. , HAN M.
Published: September 2007

Highly ordered crystalline and amorphous Si nanoarrays have been formed by using self-assembled monolayer of polystyrene nanospheres as a template followed by dry ion etching treatments. The template was removed by annealing at 8°C and pattern transfer process was revealed by atomic force microscopy. It was shown that the ordered Si nanotips with a height about 70–80 nm and an average lateral size around 150 nm can be obtained. Field emission with low threshold electric field (<10 V/μm) was demonstrated for both samples which can be attributed to the enhancement of local field due to the existence of surface nanostructures. Our results provide a simple and cheap way to make Si field emitters.
PREPARATION AND CHARACTERIZATIONS OF PTFE GRADIENT NANOSTRUCTURE ON SILK FABRIC
Authors: HUANG F. L. , WEI Q. F. , XU W. Z. , LI Q.
Published: September 2007

Superhydrophobic materials have been extensively studied because of their wonderful array of properties and applications. In this study, normal and superhydrophobic surface of silk fabric have been prepared via deposition of different shapes of PTFE nanostructure using magnetron sputter coating. The effects of PTFE sputter coating on surface morphology and surface chemical properties were characterized using atomic force microscopy (AFM) and ATR-FTIR (attenuated total reflection-Fourier transform infrared spectroscopy). The wettability of the fabric was characterized through measuring the surface contact angle by drop shape analysis apparatus and dynamic contact angle by Wilhelmy technique. As evaluated by water contact angle measurements, all the treatments resulted in a significant enhancement in the hydrophobicity of silk fabric, while larger sputtering pressures brought bigger PTFE nanoparticles, which led to higher contact angles. The results have also revealed that alternant working pressures, could bring gradient nanostructures which generated both high contact angle and less contact angle hysteresis.
NANOSTRUCTURED ANTIBACTERIAL SILVER DEPOSITED ON POLYPROPYLENE NONWOVENS
Authors: HONG-BO WANG , JIN-YAN WANG , QU-FU WEI , JIAN-HAN HONG , XIAO-YAN ZHAO
Published: September 2007

Nanostructured silver films were deposited on polypropylene (PP) nonwovens by RF magnetron sputter coating to obtain the antibacterial properties. Shake flask test was used to evaluate the antibacterial properties of the materials. Atomic force microscope (AFM) was utilized to observe the surface morphology. Energy-dispersive X-ray (EDX) was also employed to analyze the surface elemental compositions. The antibacterial results indicated that the prolonged deposition time led to a significant improvement in antibacterial effect, and sputtering power and argon pressure did not show obvious effect on antibacterial performance. It is believed that the total amount of silver ions released from the silver coating was increased as the deposition time increased. AFM images and quantitative analysis of EDX, respectively revealed that increase in deposition time led to the increased coverage of silver film and the increased silver weight percentage per unit surface, which provided evidences for the increased release rate of silver ions from the coating. Moreover, it was found that the optimum silver coating thickness was about 3 nm, taking antibacterial effect and cost of production into account.
EFFECT OF SURFACE TREATMENT ON THE ENZYMATIC TREATMENT OF CELLULOSIC FIBER
Authors: KAN C. W. , YUEN C. W. M. , JIANG S. Q.
Published: September 2007

Fiber modifications by environmentally friendly processing are essential in order to simplify the preparation and finishing processes, in addition to minimizing the chemical waste and associated disposal problem. In this regard, enzymes have been used extensively because it can remove the small fiber ends from yarn surface to create a smooth fabric surface appearance and introduce a degree of softness without using traditional chemical treatment. However, a significant strength reduction and slow reaction rate of the enzymatic reaction limit its industrial application. In this paper, the potential of using low-temperature plasma (LTP) as a surface pre-treatment prior to enzyme treatment on flax fiber has been studied. By means of the LTP pre-treatment, the effectiveness of enzyme treatment can be enhanced.
USING NANO-TiO2 AS CO-CATALYST FOR IMPROVING WRINKLE-RESISTANCE OF COTTON FABRIC
Authors: YUEN C. W. M. , KU S. K. A. , KAN C. W. , CHENG Y. F. , CHOI P. S. R. , LAM Y. L.
Published: September 2007

In order to prevent cotton wrinkling, hydroxyl groups in the cellulose chain of cotton are partially crosslinked to keep the chain fixed relative to each other with dimethylol dihydroxy ethylene urea (DMDHEU). However, DMDHEU suffers disadvantages of reduced fabric strength and releasing of free formaldehyde. Recently, 1,2,3,4-butane tetracarboxylic acid (BTCA) has been explored as a new wrinkle-resistant agent providing similar performance to that of DMDHEU. In BTCA finishing, catalyst of inorganic phosphorus-containing acids was used but such phosphorus compounds have an adverse impact on the environment. In this paper, nano- TiO 2 was used as a co-catalyst with sodium hypophophite in the treatment of cotton with BTCA, and the final properties were assessed.
STUDY OF STRUCTURE OF PHOSPHATE FILM ON CARBON STEEL
Authors: ZHAO XI , WEI GANG , ZHAO XU HUI
Published: September 2007

A phosphate protective film was prepared on carbon steel. The structure of the film was analyzed with X-ray photoelectron spectra (XPS) and atomic is force microscope (AFM). AFM observed the full process of film formation clearly. XPS with rotation etch displayed multilayer structure of nanometer phosphate film. During film formation, small insoluble particles ( ZnCa 2( PO 4)2) deposit on the carbon steel surface and grew up gradually, until cover the surface entirely.
7Li NMR STUDY ON SURFACE IONIC DIFFUSION IN NANOCRYSTALLINE LiNbO3
Authors: YU YAO , GU MIN , ZHANG LILI , TANG TONG B. , LI ZHAOSHENG , YU TAO
Published: September 2007

By a wet chemical method we have prepared nano- LiNbO 3 with different crystallite sizes. Their 7 Li NMR spectra each show, on top of a broad band accompanied by two satellites, a sharp central peak whose strength decreases with growing grain size. On the other hand, for a given sample and as temperature rises, the separation between the two satellites gets wider, but the sharp peak gets narrower. From the satellite splitting we may estimate the molar ratio [ Li ]/[ Nb ] inside the nanocrystals, and this ratio is seen to be nearer to unity in a sample of smaller grain size. The sharp peak, indiscernible in bulk (mono- or microcrystalline) LiNbO 3, is attributed to Li ions in the disproportionally large surface regions of our samples. The narrowness of its linewidth arises from the fast diffusion of these ions caused by high oxygen deficiency on the surface.
DYNAMICS OF SURFACE ATOMS AND THE GROWTH AND PROPERTIES OF NANOSTRUCTURES
Authors: TSONG TIEN T.
Published: September 2007

The dynamics of surface atoms and simple molecules is closely related to the growth of surface nanostructures. The questions we ask are how atoms diffuse and interact on the surface and what kind of surface nanostructures are formed from such interactions. We also study how the physical property of surface nanostructures is related to their size and thickness. In the last few years we found that metallic nanostructures grown on the Si (111) surface exhibit strong quantum confinement and finite size effects. These effects in turn affect their growth. Some of these studies are (1) how the quantum properties of nanoislands can serve as a template for their own growth, (2) a finite size effect in a structure phase transition of nanoislands of Pb , and (3) growth of metallic nanometer size 2D magic clusters due to both electronic shell structure and atomic bond and geometrical shell structure effects. These studies demonstrate clearly that surface dynamics, electronic and atomic bond effects as well as statistical finite size effect become more and more important as the size of surface islands and clusters reduces to the nanometer range.
IMAGING 0.4 nm SINGLE-WALLED CARBON NANOTUBES WITH ATOMIC FORCE MICROSCOPY
Authors: ZHANG XIEQIU , YE JIANTING , YANG HONGWEI , ZHANG CHUN , HO KIN MING , SU TAO , WANG NING , TANG ZIKANG , XIAO XUDONG
Published: September 2007

The discovery of the single-walled carbon nanotubes (SWCNTs) with a diameter of 0.4 nm has attracted extensive attentions. In this paper we report our attempt with two methods to directly observe these SWCNTs by AFM. The first one is to deposit the SWCNTs extracted from the zeolite matrix to a flat surface for AFM observation. While one-dimensional features have been observed, the SWCNT was suspected not to adhere well to the substrate. To overcome the difficulties of weak adhesion, we attempt to expose only part of the SWCNT from the zeolite channel by cutting the zeolite crystal at an angle. This alternative method, in which the SWCNT contained zeolite crystal is polished and etched by HCl, however, did not result in a smooth enough surface and thus no one-dimensional features can be observed. The difficulties in sample preparation and possible improvements are discussed.
FABRICATION OF SILICON NANOARRAYS BY DIRECT NANOSPHERE LITHOGRAPHY
Authors: XU L. , LI W. , ZHAO W. M. , SUN P. , XU J. , MA Z. Y. , HUANG X. F. , CHEN K. J.
Published: September 2007

We present the fabrication of large-scale two-dimensional periodic silicon nanoarrays using nanosphere lithography. The techniques start from a monolayer of self-assembled polystyrene (PS) spheres of 220 nm in diameter on water surface, which works as a mask to fabricate large-scale periodic silicon nanoarrays by direct plasmatherm reactive ion (RIE) etching. AFM images of the nanoarrays show that the patterns of PS templates are well transferred to the Si surface. The tips stand 50–80 nm high and the lateral size is around 150 nm. The optimum fabrication conditions can be chosen via the analysis of the experimental data.
SYNTHESIS AND CHARACTERIZATION OF POLYURETHANE ACRYLATES FOR UV CURABLE COATING AGENTS
Authors: PARK MI NA , KANG YOUNG SOO , OH SUN WHA , AHN BYUNG HYUN , MOON MYUNG JUN
Published: September 2007

The single hydroxyl-terminated urethane acrylate oligomers were synthesized from 2-mercaptoethanol (2-MEOH), alkyl (methyl, butyl, and 2-ethylhexyl) acrylate, and 2,2-azobisisobutyronitrile (AIBN, initiator), with dibutyltin dilaurate (DBTDL) as a catalyst. 2-MEOH was used as a functional chain transfer agent. Poly(alkyl urethane) acrylate oligomers were obtained by the reaction of single hydroxyl-terminated polyalkyl acrylates and 2-isocyanatoethyl acrylate. They were characterized by NMR, FT-IR spectroscopy, rheometer, and DSC. Because poly(alkyl urethane) acrylate oligomers have lower Tg and viscosity than hydroxyl-terminated polyalkyl acrylate oligomers (HTPAO) non-containing urethane groups, they can be used for ultraviolet (UV) curable coatings, inks, and adhesives.
INVESTIGATIONS OF THE INDENTATION-INDUCED CRYSTALLOGRAPHIC PHASE CHANGES IN SILICON USING RAMAN SPECTROSCOPY
Authors: CHAUDHRI M. M. , KHAYYAT M. M. O. , HASKO D. G.
Published: September 2007

Raman spectroscopy, which is a non-destructive technique, has been used to investigate the effect of sample temperature on indentation-induced crystallographic phase transitions in crystalline silicon and amorphous silicon films deposited on a sapphire crystal. It has been shown that in both types of sample, whereas 300 K Vickers diamond indentations lead to the transformation to the Si -II phase during indenter loading on the crystalline and amorphous samples, there is no such transformation in either sample when it is cooled down to 77 K. An explanation of the experimental results has been provided using the pressure–temperature phase diagram of silicon.
XPS STUDY OF DOPING MECHANISM IN HEAVILY DOPED PbWO4:M3+(M = La, Nd, Gd) CRYSTALS
Authors: FENG XIQI , LI WEIFENG , ZHU WENLIANG
Published: September 2007

Lead tungstate ( PbWO 4) (PWO) crystals doped with high concentration trivalent rare earth ions have demonstrated to be a promising Cherenkov radiator material and also a potential material for optoelectronic application. In this paper, the doping mechanisms of the trivalent ions ( La 3+, Nd 3+, and Gd 3+) in the PWO host were studied using X-ray photoelectron spectroscopy (XPS), and the results were consistent with those of computer simulation. It was found that when heavily doped, La 3+ may substitute for the W sites as well as the Pb sites for self-compensation by forming La dimers or small aggregates. However, the doping mechanism of heavily doped PWO: Nd 3+ and PWO: Gd 3+ might be different from that of heavily doped PWO: La 3+ crystals.
GROWTH OF METAL NANO-CLUSTERS ON METAL AND OXIDE SURFACES: A RHEED STUDY
Authors: ZEI M. S.
Published: September 2007

The powerful RHEED technique has been demonstrated for the structural determination of the nano-crystals grown on metal and oxide substrate surfaces. Pt was electrochemically deposited onto a [Formula: see text] electrode, while Pb and cobalt were vapor deposited onto Ag (111) and oxide film/ NiAl (100), respectively under UHV conditions. At any Pt coverage, 3D-clusters develop for which the Pt clusters grow in (311) orientation on the [Formula: see text] substrate surface, where the [Formula: see text] atomic rows of the (311) facet are parallel to the [Formula: see text] atomic rows of the [Formula: see text] surface. Due to the strong bonding at Pb / Ag (111) interface, the Pb deposit grows in 2D-islands with a [Formula: see text] phase (Θ < 1 ML). On the other hand, the β-crystallites of ≈ 1 nm in diameter with inclusion of smaller-sized particles (D < 1 nm ) are observed on Θ- Al 2 O 3 after Co deposition at room temperature. Annealing at 900 K Co clusters (≈ 3 nm) grow larger at expense of small particles on thin oxide film on NiAl (100) and become better ordered, where the [110] axis of the Co (001) facet is parallel to the [100] direction of the (001)-oxide surface. The in-plane lattice constant of Co clusters is ca. 4 larger than that of bulk Co , yielding less strain at the (001)-oxide surface. These results demonstrate that both orientation and phase of metal nano-clusters are governed by surface structure of the substrate.
THE SURFACE- AND SIZE-DEPENDENT ELASTIC MODULI OF NANOSTRUCTURES
Authors: GUO JIAN-GANG , ZHAO YA-PU
Published: September 2007

A theoretical model is presented to investigate the size-dependent elastic moduli of nanostructures with the effects of the surface relaxation surface energy taken into consideration. At nanoscale, due to the large ratios of the surface-to-volume, the surface effects, which include surface relaxation surface energy, etc., can play important roles. Thus, the elastic moduli of nanostructures become surface- and size-dependent. In the research, the three-dimensional continuum model of the nanofilm with the surface effects is investigated. The analytical expressions of five nonzero elastic moduli of the nanofilm are derived, and then the dependence of the elastic moduli is discussed on the surface effects and the characteristic dimensions of nanofilms.
ESTIMATING THE SEGREGATION ENERGIES IN Cu BINARY SYSTEMS
Authors: ROOS W. D. , OLIVIER G. J. , TERBLANS J. J.
Published: September 2007

The segregation energy of diluted species in a matrix can be calculated by first principles. These calculations are generally very computational demanding. The existing empirical models which use the difference in surface tensions to predict the segregation energy are limited, because they do not take the surface orientation of the matrix into account. In this investigation a model was developed which can estimate the segregation energies of segregating species in a binary system. The model makes use of the sublimation energies and takes the orientation of the surface into account. The model shows that the driving force for segregation is not the difference in surface tensions (between the surface tension of the pure element and the surface tension of the element in the alloy) but the difference in surface energies. The results of the calculations were used to simulate the Ag and Sb segregation to the (111) surface of copper.
A PROCEDURE TO DETERMINE THE SEGREGATION PARAMETERS IN TERNARY SYSTEMS FROM EXPERIMENTAL DATA OF A LINEAR TEMPERATURE RUN
Authors: ROOS W. D. , ASANTE J. K. O.
Published: September 2007

Profiles of surface concentrations as a function of temperature, where the temperature is increased at a constant rate, contain the necessary information to extract segregation parameters. A model using rate equations can be used to simulate these profiles. Even on a high-speed computer, solving these equations can take hours. For ternary and higher component alloys the fit parameters are at least nine and finding the best fit manually can extend the search to days. Theoretical segregation and diffusion models show two temperature regions of interest. In the low-temperature region, representing the kinetics of segregation, the diffusion coefficients of the species dominate the flux of atoms to the surface, and in the high-temperature region the surface concentrations are independent of the diffusion coefficients. In the high-temperature equilibrium region the surface concentrations are determined only by the segregation energies and interaction coefficients. A procedure is presented that can find a good set of segregation parameters within seconds. The sensitivity of selecting the kinetics, as well as the equilibrium temperature regions will be demonstrated. The procedure is used to extract the segregation parameters for a Cu (111) 0.13 at% Sn 0.18 at% Sb system.
MoSi2-IMPROVED SiC COATING TO PROTECT CARBON/CARBON COMPOSITES AGAINST OXIDATION
Authors: FU QIANGANG , XUE HUI , LI HEJUN , LI KEZHI , SHI XIAOHONG
Published: September 2007

To improve the oxidation protective ability of SiC coating for carbon/carbon ( C / C ) composites, MoSi 2 was introduced in the SiC coating by infiltration technique. XRD and SEM analysis show that the SiC coating obtained by pack cementation is a porous structure with a thickness of about 60–100 μm. After infiltration treatment, MoSi 2 was filled in the holes of the porous SiC -coating, and the as-received coating becomes dense without through-thickness crack. Oxidation test shows that, the weight loss of the SiC -coated C / C is up to 9.23% after 53 h oxidation in air at 1773 K, while the weight loss of the MoSi 2-improved SiC -coated C / C composites is only 0.73% after oxidation for 265 h. The oxidation of C / C composites is primarily due to the formation of the penetration cracks and the holes on the glass layer.
CHARACTERIZATION OF DYNAMIC WETTING OF PLASMA-TREATED PTFE FILM
Authors: WEI Q. F. , LIU Y. , HUANG F. L. , HONG S. H.
Published: September 2007

Polytetrafluoroethylene (PTFE) has been increasingly used in many industries due to its low frictional coefficient and excellent chemical inertness. The surface properties of PTFE are of importance in various applications. The surface properties of PTFE can be modified by different techniques. In this study, PTFE film was treated in oxygen plasma for improving surface wettability. The effects of plasma treatment on dynamic wetting behavior were characterized using Scanning Probe Microscopy (SPM), Fourier transform infrared spectroscopy (FTIR), and dynamic contact angle (DCA) measurements. SPM observations revealed the etching effect of the plasma treatment on the film. The introduction of hydrophilic groups by plasma treatment was detected by FTIR. The roughened and functionalized surface resulted in the change in both advancing and receding contact angles. Advancing and receding contact angles were significantly reduced, but the contact angle hysteresis was obviously increased after plasma treatment.
INTEGRATION OF LASER MBE GROWN OXIDE THIN FILMS OF SrTiO3 WITH YBa2Cu3Oy FOR TUNABLE APPLICATIONS
Authors: HAO J. H. , GAO J.
Published: September 2007

The frequency tuning can be achieved by integrating SrTiO 3 (STO) thin films into high-temperature superconducting YBa 2 Cu 3 O y (YBCO) devices and tuning the dielectric constant of the STO films by an electrical bias. We have fabricated epitaxial STO thin films on superconducting YBCO. By the combination of various surface characterizations such as scanning probe microscope, structural and dielectric measurements, we attempted to understand the fundamental mechanisms of dielectric properties in STO thin films. Substrate surface and structural properties of the heterostructure were studied. We have measured the temperature dependence of dielectric constant and loss tangent of STO thin films. The system exhibits 41% dielectric constant tuning over a bias of 4 V at low temperature.
SURFACE MORPHOLOGY AND TRANSPORT PROPERTY IN La2/3Ca1/3MnO3, YBa1.8Eu0.2Cu3O7 PERIODIC FILMS
Authors: ZHANG Y. M. , JIANG Z. S. , WU X. S. , TAN W. S. , GAO J.
Published: September 2007

The structure and transport properties for La 2/3 Ca 1/3 MnO 3 (LCMO)/ YBa 1.8 Eu 0.2 Cu 3 O 7 (YBECO) multilayers are studied. The lattice constants for each sub-layer decrease with decreasing the temperature. The morphology of the films depends on the thickness of each sub-layer. Grains growing on the surface of each sample are believed to release the lattice strain. We believe that the lattice strain may affect the transport properties of LCMO and YBECO in the periodic films. The grains appearing on the surface of the film may enlarge the width of the superconducting transition of YBECO, and the metal-to-insulator transition of LCMO.
EFFECT OF SUBSTRATE TEMPERATURE ON THE STRUCTURAL AND THE OPTICAL PROPERTIES OF CdTe (100) EPITAXIAL FILMS GROWN ON GaAs (100) SUBSTRATES
Authors: LEE D. U. , JUNG J. H. , KIM T. W. , LEE H. S. , PARK H. L. , LEE K. H.
Published: September 2007

CdTe thin films were grown on GaAs (100) substrates by using molecular beam epitaxy at various temperatures. The results of the X-ray diffraction (XRD) patterns showed that the orientation of the grown CdTe thin films was the (100) orientation. XRD patterns, atomic force microscopy images, high-resolution transmission electron microscopy (HRTEM) images, and photoluminescence spectra showed that the crystallinity of CdTe (100) epilayers grown on GaAs (100) substrates was improved by increasing the substrate temperature. HRTEM images showed that misfit dislocations existed at the CdTe / GaAs heterointerface. These results can help improve understanding of the substrate temperature effect on the structural and the optical properties of CdTe (100)/ GaAs (100) heterostructures.
STUDIES ON THE HETEROJUNCTION STRUCTURE OF n-Si/p-NANOCRYSTALLINE DIAMOND FILM
Authors: WANG LINJUN , LIU JIANMIN , REN LING , SU QINGFENG , XU RUN , SHI WEIMIN , XIA YIBEN
Published: September 2007

An undoped p-type nanocrystalline diamond (NCD) film was grown by an electron assisted hot filament chemical vapor deposition (EA-HFCVD) technology on an n-type single-crystalline Si substrate to fabricate p-NCD/n- Si heterojunction. The structure and morphology of the NCD film, which was analyzed by Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM), showed that the film consisted of 40–60 nm polycrystalline nano-grains. The results showed that with EA-HFCVD method, not only an undoped NCD film with high conductivity but also a p–n heterojunction diode between the NCD film and n- Si substrate was fabricated successfully. The p-NCD/n- Si heterostructure was also used for ultraviolet (UV) photodetector application. Operating at a bias voltage of 10 V, this photodetector showed a significant discrimination between UV and visible light, and the UV/visible-blind ratio was about three orders of magnitude.
DENSITY OF SURFACE STATES IN Pd/SiGe/Si INTERFACE FROM CAPACITANCE MEASUREMENTS
Authors: SELLAI A. , MAMOR M. , AL-HARTHI S.
Published: September 2007

Pd / Si 0.9 Ge 0.1/ Si Schottky barrier diodes subjected to irradiation are characterized using capacitance and conductance measurements performed under forward and reverse bias while varying the temperature and frequency. The C–V technique has been used in particular to determine the carriers profile as well as the interface state density and its energy distribution.
A BILAYER BUFFER USING 214T Eu2CuO4 AND CUBIC YSZ FOR GROWING YBa2Cu3Oy THIN FILMS ON Si
Authors: GAO J. , FU E. G. , WU X. S.
Published: September 2007

Highly epitaxial thin films of YBa 2 Cu 3 O y (YBCO) have been successfully grown on Si using a double buffer of Eu 2 CuO 4 (ECO)/(yttrium-stabilized zirconia) YSZ. The severe reaction between Si and YBCO is blocked by YSZ, and the crystallinity and superconductivity of the grown YBCO due to the lattice mismatch between YBCO and YSZ are improved by the ECO layer. The grown films were characterized by high-resolution X-ray diffraction, grazing incidence X-ray reflection, scanning electron microscopy (SEM), and Doppler broadened annihilation radiation spectroscopy, respectively. Very clear interfaces were found at YBCO/ECO/YSZ boundaries without any intermediate layer. The YBCO film surface was more smooth and stable. The results obtained indicate that highly epitaxial YBCO thin films can be successfully grown on Si wafers, demonstrating advantages of such a double buffer structure.
DISLOCATION DENSITY IN SrTiO3 FILM GROWN ON DyScO3 BY PULSE LASER ABLATION
Authors: ZHAI Z. Y. , LI X. Z. , ZHI S. S. , WU X. S. , HAO J. H. , GAO J.
Published: September 2007

SrTiO 3 films are fabricated on DyScO 3 substrates by pulse laser deposition. In situ X-ray diffraction (XRD) is used to characterize the thermal expansion coefficient at low temperature. The abnormal behavior in lattice parameter at 80 K may be the hint of a phase transition. High resolution XRD is performed to detect the two kinds of dislocations, i.e. screw and edge. Results show that the density of edge dislocation is a little larger than that of the screw one. The total dislocation density has the order of about 108 cm-2. Edge dislocation density decreases with the increase of the film thickness. We argue that the ratio between these two dislocation densities results in the growth mode of the film.
HOMO-EPITAXIAL GROWTH ON ZnO SUBSTRATE BY MO-CVD USING (C5H7O2)2
Authors: HAGA KOICH , SHISHIDO TOETSU , NAKAJIMA KAZUO , MATSUNAGA TAKAHIRO
Published: September 2007

High quality homo-epitaxial ZnO films were grown on Zn -terminated surfaces of ZnO (0001) single-crystal substrates with high-temperature annealing and Ar + ion etching. These films were prepared by low-pressure MO-CVD using zinc acetylacetonate ( C 5 H 7 O 2)2 and oxygen as source materials. High quality ZnO (0001) substrate was synthesized by the hydrothermal technique. The atomically flat surface without scratches was obtained by high temperature annealing at 800°C–1300°C in oxygen atmosphere. Ar + ion etching for the surface of ZnO substrates was critically important to the growth of ZnO films with good crystallinity. The epitaxial film and the ZnO substrate were characterized using reflection high-energy electron diffraction, atomic force microscope, and X-ray photoelectron spectroscopy.
ADHERENT NANO-SUPERHARD TITANIUM NITRIDE FILM AND ITS FORMING MECHANISM IN MULTI-ARC ION-PLATING SYSTEM
Authors: YU XIANG , WANG CHENGBIAO , HUA MENG , TAM PUILAM , LIU YANG , YU DEYANG
Published: September 2007

An adherent nano-superhard titanium nitride ( TiN ) film on the substrate of Cr 12 Mo 4 V high speed steel was prefabricated in a vacuum cathode multi-arc ion-plating system. Microhardness, film-to-substrate adhesion, and microstructure of the film were investigated typically using Vickers hardometer, scratch tester, and X-ray diffractometer. Results show that: (i) the achievable film microhardness is in the range of 35–45 GPa; (ii) the critical load (Lc) of the superhard TiN film is approximately 64 N; (iii) the nm scale mean main grain sizes of the film are approximately of 12.7 nm for TiN 111, 19.7 nm for TiN 200, and 9.6 nm for TiN 220; and (iv) compared with the standard TiN film with the hardness of 22 GPa, the accomplishment of the nano-superhard TiN film may be due to (a) the ion bombardment induced residual stress within the film, and (b) the combined effect of the decrease of crystalline size and preferred orientation in the plane (111).
THE STRUCTURE AND TRANSPORT PROPERTIES OF La0.9Sr0.1MnO3
Authors: LUO Z. , GAO J.
Published: September 2007

Thin films of La 0.9 Sr 0.1 MnO 3 (LSMO) were grown on SrTiO 3 substrate by pulsed laser deposition technique at different temperatures and with various oxygen partial pressures. X-ray diffraction spectra confirmed that the grown films are of single phase. The influence of oxygen deficiency on the structure of these grown films has been studied. X-ray diffraction data suggested that higher oxygen content generally results in smaller out-of- plane lattice parameters and annealing in oxygen may further decrease the lattice parameters. The 2-θ value increases with oxygen pressure. Typically, the oxygen-deficient films behave like semiconductors. For films grown at the same temperature, the conductivity is enhanced if the oxygen content is increased. Those films grown in 1 mbar oxygen partial pressure show an upturn at low temperature. Resistivity is dominated by the hopping of adiabatic small polarons at high temperature.
ELECTRONIC PARAMETER AND SUBBAND STRUCTURE VARIATIONS DUE TO AN EMBEDDED AlN POTENTIAL BARRIER LAYER IN Al0.3Ga0.7N/GaN HETEROSTRUCTURES
Authors: HAN S. M. , KIM S. Y. , CHOO D. C. , JUNG J. I. , KIM T. W. , YOO K. H. , JO Y. H. , JUNG M. H. , CHO H. I. , LEE J. H. , RAM-MOHAN L. R.
Published: September 2007

Carrier density of a two-dimensional electron gas (2DEG) in Al 0.3 Ga 0.7 N / GaN and Al 0.3 Ga 0.7 N / AlN / GaN heterostructures was investigated by performing Shubnikov-de Haas (SdH) measurements. The angular-dependent SdH measurements and the fast Fourier transformation results for the SdH data indicated 2DEG occupation of one subband in the triangular potential wells. The carrier densities of the 2DEGs in the Al 0.3 Ga 0.7 N / AlN / GaN and the Al 0.3 Ga 0.7 N / GaN heterostructures at 1.5 K, determined from the SdH data, were 1.28 × 1013 and 1.12 × 1013 cm-2, respectively. The electron carrier density of the 2DEG in the Al 0.3 Ga 0.7 N / GaN heterostructure with an AlN embedded potential barrier layer was larger than that in the Al 0.3 Ga 0.7 N / GaN heterostructure. The electronic subband energies, the wave functions, and the Fermi energies in the Al 0.3 Ga 0.7 N / AlN / GaN and Al 0.3 Ga 0.7 N / GaN heterostructures were calculated by using a self-consistent method taking into account spontaneous and piezoelectric polarizations.
THE INFLUENCE OF SiC COATING PROCESS ON THE PROPERTIES OF C/C COMPOSITES
Authors: HUANG MIN , LI KE-ZHI , LI HE-JUN , FU QIAN-GANG , SUN GUO-DONG
Published: September 2007

SiC coating for carbon/carbon composites was prepared by pack cementation method. The effects of coating process on the microstructure and the mechanical properties of C / C composites were analyzed by SEM and three-point bending test, respectively. As the infiltrated Si improved the interfaces bonding during the coating process, the flexural strength and flexural modulus of SiC -coated carbon/carbon composites were both increased by about 10% than the naked C / C composites. In addition, the mechanism of the change of failure mode of SiC coated C / C composites and naked C / C composites was addressed.
PREDICTION OF cis-REGULATORY ELEMENTS: FROM HIGH-INFORMATION CONTENT ANALYSIS TO MOTIF IDENTIFICATION
Authors: LI GUOJUN , LU JIZHU , OLMAN VICTOR , XU YING
Published: September 2007

One popular approach to prediction of binding motifs of transcription factors is to model the problem as to search for a group of l-mers (motifs), for some l > 0, one from each of the provided promoter regions of a group of co-expressed genes, that exhibit high information content when aligned without gaps. In our current work, we assume that these desired l-mers have evolved from a common ancestor, each of which has mutations in at most k-positions from the common ancestor, where k is substantially smaller than l. This implies that these l-mers should belong to the k-neighborhood of their common ancestor, measured in terms of Hamming distance. If the ancestor is given, then the problem for finding these l-mers becomes trivial. Unfortunately, the problem of identifying the unknown ancestor is probably as hard as the problem of predicting the motifs themselves. Our goal is to identify a set of l-mers that slightly violate the k-neighborhood of a putative ancestor, but capture all the desired motifs, which will lead to an efficient way for identification of the desired motifs. The main contributions of this paper are in four aspects: (a) we have derived nontrivial lower and upper bounds of information content for a set of l-mers that differ from an unknown ancestor in no more than k positions; (b) we have defined a new distance between two sequences and a k-pseudo-neighborhood, based on the new distance, that contains the k-neighborhood, defined by Hamming distance, of the to-be-defined ancestor; (c) we have developed an algorithm to minimize the sum of all the distances between a predicted ancestor motif and a group of l-mers from the provided promoter regions, using the new distance; and (d) we have tested PROMOCO and compared its prediction results performance with two other prediction programs.

The algorithm, implemented as a computer software program PROMOCO, has been used to find all conserved motifs in a set of provided promoter sequences. Our preliminary application of PROMOCO shows that it achieves better or comparable prediction results, when compared to popular programs for identification of cis regulatory binding motifs. A limitation of the algorithm is that it does not work well when the size of the set of provided promoter sequences is too small or when desired motifs appear in only small portion of the given sequences.
ALGORITHMIC APPROACHES TO SELECTING CONTROL CLONES IN DNA ARRAY HYBRIDIZATION EXPERIMENTS
Authors: FU QI , BENT ELIZABETH , BORNEMAN JAMES , CHROBAK MAREK , YOUNG NEAL E.
Published: September 2007

We study the problem of selecting control clones in DNA array hybridization experiments. The problem arises in the OFRG method for analyzing microbial communities. The OFRG method performs classification of rRNA gene clones using binary fingerprints created from a series of hybridization experiments, where each experiment consists of hybridizing a collection of arrayed clones with a single oligonucleotide probe. This experiment produces analog signals, one for each clone, which then need to be classified, that is, converted into binary values 1 and 0 that represent hybridization and non-hybridization events. In addition to the sample rRNA gene clones, the array contains a number of control clones needed to calibrate the classification procedure of the hybridization signals. These control clones must be selected with care to optimize the classification process. We formulate this as a combinatorial optimization problem called Balanced Covering. We prove that the problem is ℕℙ-hard, and we show some results on hardness of approximation. We propose approximation algorithms based on randomized rounding, and we show that, with high probability, our algorithms approximate well the optimum solution. The experimental results confirm that the algorithms find high quality control clones. The algorithms have been implemented and are publicly available as part of the software package called CloneTools.
A PRACTICAL QUESTION BASED ON CROSS-PLATFORM MICROARRAY DATA NORMALIZATION: ARE BOEC MORE LIKE LARGE VESSEL OR MICROVASCULAR ENDOTHELIAL CELLS OR NEITHER OF THEM?
Authors: JIANG AIXIANG , PAN WEI , MILBAUER LIMING C. , SHYR YU , HEBBEL ROBERT P.
Published: September 2007

Since the available microarray data of BOEC (human blood outgrowth endothelial cells), large vessel, and microvascular endothelial cells were from two different platforms, a working cross-platform normalization method was needed to make these data comparable. With six HUVEC (human umbilical vein endothelial cells) samples hybridized on two-channel cDNA arrays and six HUVEC samples on Affymetrix arrays, 64 possible combinations of a three-step normalization procedure were investigated to search for the best normalization method, which was selected, based on two criteria measuring the extent to which expression profiles of biological samples of the same cell type arrayed on two platforms were indistinguishable. Next, three discriminative gene lists between the large vessel and the microvascular endothelial cells were achieved by SAM (significant analysis of microarrays), PAM (prediction analysis for microarrays), and a combination of SAM and PAM lists. The final discriminative gene list was selected by SVM (support vector machine). Based on this discriminative gene list, SVM classification analysis with best tuning parameters and 10,000 times of validations showed that BOEC were far from large vessel cells, they either formed their own class, or fell into the microvascular class. Based on all the common genes between the two platforms, SVM analysis further confirmed this conclusion.
MODELING CANCER: INTEGRATION OF "OMICS" INFORMATION IN DYNAMIC SYSTEMS
Authors: STRANSKY BEATRIZ , BARRERA JUNIOR , OHNO-MACHADO LUCILA , DE SOUZA SANDRO J.
Published: September 2007

The last 10 years have seen the rise of many technologies that produce an unprecedented amount of genome-scale data from many organisms. Although the research community has been successful in exploring these data, many challenges still persist. One of them is the effective integration of such data sets directly into approaches based on mathematical modeling of biological systems. Applications in cancer are a good example. The bridge between information and modeling in cancer can be achieved by two major types of complementary strategies. First, there is a bottom–up approach, in which data generates information about structure and relationship between components of a given system. In addition, there is a top–down approach, where cybernetic and systems–theoretical knowledge are used to create models that describe mechanisms and dynamics of the system. These approaches can also be linked to yield multi-scale models combining detailed mechanism and wide biological scope. Here we give an overall picture of this field and discuss possible strategies to approach the major challenges ahead.