bluuebunny/crossref_metadata_2025 huggingface dataset:
NONPERTURBATIVE TACHYON POTENTIAL FROM THE WILSONIAN RENORMALIZATION GROUP
Authors: O'DWYER JAMES P.
Published: May 2005

The derivative expansion of the Wilsonian renormalization group generates additional terms in the effective β-functions not present in the perturbative approach. Applied to the nonlinear σ-model, to lowest order the vanishing of the β-function for the tachyon field generates an equation analogous to that found in open string field theory. Although the nonlinear term depends on the cutoff function, this arbitrariness can be removed by a rescaling of the tachyon field.
EXPERIMENTAL TESTS OF TIME DILATION IN SPECIAL RELATIVITY
Authors: GWINNER GERALD
Published: May 2005

A review of experimental tests of time dilation in special relativity is given, with an emphasis on the recent heavy-ion storage-ring work, currently the most sensitive method. The experimental results are evaluated in the context of the kinematic test theories of Robertson and Mansouri and Sexl, which assume the existence of a preferred inertial reference frame. Prospects for future improvements and the sensitivity of time dilation experiments to Lorentz and CPT violating extensions of the standard model are discussed.
A FRACTAL VALUED RANDOM ITERATION ALGORITHM AND FRACTAL HIERARCHY
Authors: BARNSLEY MICHAEL , HUTCHINSON JOHN , STENFLO ÖRJAN
Published: June 2005

We describe new families of random fractals, referred to as "V-variable", which are intermediate between the notions of deterministic and of standard random fractals. The parameter V describes the degree of "variability": at each magnification level any V-variable fractals has at most V key "forms" or "shapes". V-variable random fractals have the surprising property that they can be computed using a forward process. More precisely, a version of the usual Random Iteration Algorithm, operating on sets (or measures) rather than points, can be used to sample each family. To present this theory, we review relevant results on fractals (and fractal measures), both deterministic and random. Then our new results are obtained by constructing an iterated function system (a super IFS) from a collection of standard IFSs together with a corresponding set of probabilities. The attractor of the super IFS is called a superfractal; it is a collection of V-variable random fractals (sets or measures) together with an associated probability distribution on this collection. When the underlying space is for example ℝ2, and the transformations are computationally straightforward (such as affine transformations), the superfractal can be sampled by means of the algorithm, which is highly efficient in terms of memory usage. The algorithm is illustrated by some computed examples. Some variants, special cases, generalizations of the framework, and potential applications are mentioned.
TOWARD A QUANTIFICATION OF SELF-SIMILARITY IN PLANTS
Authors: FERRARO PASCAL , GODIN CHRISTOPHE , PRUSINKIEWICZ PRZEMYSLAW
Published: June 2005

Self-similarity of plants has attracted the attention of biologists for at least 50 years, yet its formal treatment is rare, and no measure for quantifying the degree of self-similarity currently exists. We propose a formal definition and measures of self-similarity, tailored to branching plant structures. To evaluate self-similarity, we make use of an algorithm for computing topological distances between branching systems, developed in computer science. The formalism is illustrated using theoretical branching systems, and applied to analyze self-similarity in two sample plant structures: inflorescences of Syringa vulgaris (lilac) and shoots of Oryza sativa (rice).
FRACTAL ANALYSIS OF PYRAMIDAL CELLS IN THE VISUAL CORTEX OF THE GALAGO (OTOLEMUR GARNETTI): REGIONAL VARIATION IN DENDRITIC BRANCHING PATTERNS BETWEEN VISUAL AREAS
Authors: ZIETSCH BRENDAN , ELSTON GUY N.
Published: June 2005

Previously it has been shown that the branching pattern of pyramidal cells varies markedly between different cortical areas in simian primates. These differences are thought to influence the functional complexity of the cells. In particular, there is a progressive increase in the fractal dimension of pyramidal cells with anterior progression through cortical areas in the occipitotemporal (OT) visual stream, including the primary visual area (V1), the second visual area (V2), the dorsolateral area (DL, corresponding to the fourth visual area) and inferotemporal cortex (IT). However, there are as yet no data on the fractal dimension of these neurons in prosimian primates. Here we focused on the nocturnal prosimian galago (Otolemur garnetti). The fractal dimension (D), and aspect ratio (a measure of branching symmetry), was determined for 111 layer III pyramidal cells in V1, V2, DL and IT. We found, as in simian primates, that the fractal dimension of neurons increased with anterior progression from V1 through V2, DL, and IT. Two important conclusions can be drawn from these results: (1) the trend for increasing branching complexity with anterior progression through OT areas was likely to be present in a common primate ancestor, and (2) specialization in neuron structure more likely facilitates object recognition than spectral processing.
HIGH RESOLUTION ELECTRON MICROSCOPY STUDY OF A NOVEL NANOSTRUCTURE OF TITANIUM DIOXIDE
Authors: MA G. B. , ZHU J. M. , MING N.-B.
Published: May 2005

Chestnut-bur-like assemblies composed of rutile TiO 2 acicular nanocrystals with radial coagulation in all directions are synthesized by a sonochemical method. High resolution electron microscopy investigations indicate that the growth direction of the acicular nanocrystals is along rutile TiO 2 [001], bending features almost all of these nanocrystals, and misoriented attachment of them results in chestnut-bur-like secondary particles.
NANOMETER CHITIN FIBER AND LAYUP OF THE CHAFER CUTICLE
Authors: CHEN B. , WANG J. , PENG X. , CAI C. , WU X.
Published: May 2005

Most structural materials existing in nature take the form of a composite. After centuries of evolution, these materials have gained highly optimized microstructures and performance. In this work, a natural biocomposite, chafer cuticle, was observed with SEM, and it was found that the insect cuticle has a laminated structure with chitin fiber and protein matrix. Special helicoidal layups of chitin fibers were found with the chitin fiber being of nanometer scale. The relationship between the nanometer scale of the chitin fiber and the fracture strength of the cuticle was analyzed. The results show that the nanometer scale of the chitin fiber is profitable to maintain and improve the fracture strength of the biocomposite.
CHARACTERIZATION OF NANOSTRUCTURES IN BULK ALLOYS BY ELECTRICAL RESISTIVITY MEASUREMENTS
Authors: SPOWAGE A. C. , CHANDRASEKARAN M.
Published: May 2005

The control of nanostructural features such as clusters and precipitates offers tremendous potential for improvements in the properties of advanced alloys. However, due to their inherently small size characterization is a major problem. Techniques such as TEM, AFM, and FIM have sufficient resolution, however they are only able to sample a small volume of what is a bulk material. Other characterization techniques such as XRD and DSC are capable of producing more representative results but still have limitations. Electrical resistivity measurements are extremely simple and have been used to characterize conventional materials for many years. However, as the wavelength of the electrons in the metals is extremely small, the potential use of resistivity measurements for interrogating nanostructural features has not been fully explored. The paper presents how electrical resistivity measurements combined with more conventional techniques can be used to understand the evolution of the nanostructural state in advanced aluminum alloys.
MAGNETO-TRANSPORT IN NANOPATTERNED EPITAXIAL Ni FILMS
Authors: LUKASZEW R. A. , ZHANG Z. , PEARSON D. , ZAMBANO A.
Published: May 2005

The latest reports on ballistic magneto-resistance in electrochemically defined nanocontacts between Ni wires have shown surprisingly large magneto-resistive effects (several thousands percent) that are still not understood. In addition, there is strong controversy on the interpretation of this effect. Thus, in an attempt to resolve some of the relevant issues surrounding this effect, we report our work on lithographically patterned nanocontacts on epitaxial Ni films. Our results indicate that there are domain-wall related magneto-resistance effects in these nanostructures but the overall effect is only a few percent at room temperature. We believe that the observed effect is due to diffusive domain wall scattering at the nanocontacts.
SURFACE NANOPATTERNING EFFECTS, STRUCTURE AND MAGNETIC PROPERTIES OF EPITAXIAL Ni FILMS
Authors: LUKASZEW R. A. , ZHANG Z. , PEARSON D. , PAN X. , CLARKE R. , YEADON M.
Published: May 2005

We have studied the correlation between film structures and the azimuthal dependence of the magnetization reversal in (001) and (111) Ni films grown on MgO substrates using molecular beam epitaxy (MBE). For as-grown (001) Ni films, the coercive field exhibits four-fold azimuthal symmetry while in-situ annealed films exhibit additional uniaxial anisotropy. In-situ STM images show surface stripe nanopatterning on the annealed films, which is absent in the as-grown ones. Cross sectional TEM seems to indicate the presence of a highly ordered interfacial layer that we postulate may be fcc NiO . Tetragonal distortion of this layer upon annealing may have induced the uniaxial anisotropy observed in the magnetic properties. Polarized neutron reflectivity measurements performed on some of the films are correlated with the interfacial surface structure and the magnetic anisotropy.
EFFECT OF SURFACE FINISHES ON THE THICKNESS AND MORPHOLOGY OF THE INTERMETALLIC LAYER IN LEAD-FREE SOLDER JOINTS
Authors: SPOWAGE A. C. , THONG C. M. , COLLIER P. A. , LI G. Y.
Published: May 2005

One of the most pressing challenges facing today's electronics packaging industry is to identify reliable and cost-effective solder alloys to replace toxic lead containing solder. Besides evaluating new alloy compositions and improving the soldering process, it is important to understand how surface finishes applied to the copper metallization affect the joint characteristics. The characterization of intermetallics during the early stages of nucleation and the growth is hindered by the nanoscopic grain size and layer thickness. This study investigates the impact of PCB finish and solder type on the interfacial intermetallics. Five types of solder and four types of finishes were used: Sn37Pb (SP), Sn3.5Ag (SA), Sn3.5Ag0.7Cu (SAC), Sn2Ag0.5Cu4Bi (SACB) and Sn3Bi8Zn (SBZ) solders, combined with immersion Silver ( I – Ag ), electroless Nickel-immersion Gold (ENIG), Organic Solderability Preservative (OSP) and immersion Tin ( I – Sn ). It was shown that both the SP and SAC solders follow a parabolic growth model and that the surface finish has a significant effect on the intermetallic morphology and growth kinetics. A combined SEM and XRD investigation was shown to be a suitable method for characterizing nanoscale intermetallics.
CONTROLLED SYNTHESIS AND CHARACTERIZATION OF TiO2 NANOPARTICLES VIA A SOL–GEL METHOD
Authors: LI YING , LIM SUO HON , WHITE TIM
Published: May 2005

The properties influencing the photocatalytic activity of TiO 2 particles have been suggested to include the surface area, crystallinity, crystallite size and crystal structure. Therefore, manipulation of the microstructure of titania, especially of nanocrystalline powders, is very important in the preparative process. In this study, nanocrystalline TiO 2 powders with controlled particle size and phase composition were synthesized at low temperature (<80°C) by a modified sol–gel method. The effects of gelation temperature were systematically investigated. It was found that this parameter played a critical role in determining the crystallinity of single phase anatase. With increasing gelation temperature, the crystallinity of anatase improved initially and then decreased if the temperature was raised to 80°C. These nanomaterials were characterized comprehensively by powder X-ray diffraction (including Rietveld analysis), high-resolution transmission electron microscopy, DSC/TGA thermal analysis and UV–Vis spectrometry.
X-RAY DIFFRACTION ANALYSIS OF NANOPARTICLES: RECENT DEVELOPMENTS, POTENTIAL PROBLEMS AND SOME SOLUTIONS
Authors: WHITFIELD PAMELA , MITCHELL LYNDON
Published: May 2005

Powder X-ray diffraction has become a cornerstone technique for deriving crystallite size in nanoscience due to speed and "simplicity". Unfortunately, this apparently simple technique commonly has unexpected problems. Anisotropic peak broadening related to crystallite shape, defects, and microstrain occurs frequently in nanomaterials and can significantly complicate the analysis. In some instances, the usage of the conventional single peak approach would give erroneous results, and in others, this type of analysis is not even possible. A number of different nanocrystalline oxides have been examined to determine their crystallite sizes by different techniques. They differ in terms of crystal symmetry, crystallinity, density, and present different challenges with regard to size analysis.
STUDY OF THE THERMAL DEPROTECTION IN A CHEMICALLY-AMPLIFIED RESIST
Authors: LU D. , XING Z. X. , GUI D. , KERSTING R.
Published: May 2005

The microlithographic process is the core process in semiconductor device manufacturing. With continuous shrinkage in device geometry, deep-ultraviolet (DUV) photolithography is required to meet the industry needs. Modern microlithography is based on chemically-amplified (CA) resist via the acid-catalyzed deprotection of the pendant groups, which can be induced by either irradiation or thermolysis. Thermally-activated deprotection can occur in unexposed areas at temperatures close to the post-exposure bake temperature. Thermal deprotection can be detected by various techniques. In this paper, FTIR, TGA, TD-GC-MS and temperature-programmed ToF-SIMS are used to study the thermal deprotection in a commercial CA resist. The initiation temperature of thermal deprotection depends on the techniques used. Understanding the thermal deprotection mechanism is very important for materials selection and process optimization.
EFFECT OF TEMPERATURE AND IRRADIATION DOSE OF He+ AND N+ IONS ON SURFACE SWELLING AT GRAIN INTERIOR AND GRAIN BOUNDARY IN TYPE 316 STAINLESS STEEL
Authors: LIU L. , MITAMURA T. , TERASAWA M. , YAMAMOTO A. , TSUBAKINO H.
Published: May 2005

Austenitic stainless steel specimens of type 316SS were irradiated by 200 keV He + ions or 200 keV N + ions. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were employed to study the fine surface deformation of the irradiated specimens. At the high temperatures of He + ion irradiation, distinct swelling was observed at grain interior and grain boundaries by AFM and helium bubbles were found by TEM. It is suggested that helium atoms agglomerate in high doses and high temperatures. The nanometer-level step height of surface swelling induced by He + ion irradiation has obvious dependence on the irradiation dose and temperature. In the case of N + ion irradiation, the swelling was observed at grain interior but the step height was less remarkable than in the case of He + ions. The swelling is induced by void formation. The caved-in grain boundaries were recognized in N + ion irradiated area.
IN-SITU TEM INVESTIGATION OF STRUCTURAL CHANGES IN ZIRCONIA/SILICON HETEROSTRUCTURES AT ELEVATED TEMPERATURE
Authors: KIGUCHI TAKANORI , WAKIYA NAOKI , SHINOZAKI KAZUO , MIZUTANI NOBUYASU
Published: May 2005

The crystallization process of Yttria Stabilized Zirconia (YSZ) thin film and the growth process of silicon oxide ( SiO x) have been directly investigated by in-situ heating TEM method from plan-view and cross-sectional directions. The YSZ layer is crystallized by the nucleation and growth mechanism. The nucleation is started from the surface region of the YSZ layer. Ultra thin SiO x layer on the surface of Si substrate plays an important role in the strain relaxation in the crystallization process.
APPLICATION OF EXIT-PLANE WAVE FUNCTION IMAGES IN HIGH-RESOLUTION TRANSMISSION ELECTRON MICROSCOPY FOR QUANTITATIVE ANALYSIS OF III–V SEMICONDUCTOR INTERFACES
Authors: MAHALINGAM K. , EYINK K. G. , BROWN G. J. , DORSEY D. L.
Published: May 2005

An image simulation study is performed to investigate the applicability of exit-plane wave function (EPWF) images for an atomic-level compositional mapping of interfaces in the GaAs – AlAs system. A simple procedure for quantifying the composition across an interface, which is based on the method of factorial analysis of correspondence is proposed. A test of this procedure on a simulated EPWF-phase image of Al 0.4 Ga 0.6 As/GaAs/Al 0.4 Ga 0.6 As structure, with an atomically abrupt interface on one side and a graded interface on the other, yields profiles which mimic the model-profiles.
THERMAL CHARACTERIZATION OF GaAsN THIN FILMS BY PULSED PHOTOTHERMAL REFLECTANCE TECHNIQUE
Authors: ZHAO YIMIN , CHEN GEORGE , WANG SHANZHONG , YOON SOON FATT
Published: May 2005

Thermal conductivity of Gallium Arsenic Nitride ( GaAsN ) epilayer on Gallium Arsenide ( GaAs ) substrate prepared by Molecular Beam Epitaxy technique was measured using pulsed photothermal reflectance technique. Within the thickness ranging from 20 nm to 80 nm, no thickness dependent relationship with thermal conductivity of GaAsN epilayer was found, and the average thermal conductivity is about 28 W/mK at room temperature.
ATOMIC FORCE MICROSCOPE (AFM)-BASED DIGITAL IMAGE SPECKLE CORRELATION (DiSC) TECHNIQUE FOR THE MEASUREMENT OF DEFORMATION IN NANOSCALE
Authors: SHI X. Q. , PICKERING J. P. , WONG C. K.
Published: May 2005

Experimental measurement techniques for the determination of stress levels and distributions will be one of most important keys for the optimization of the design of the next generation electronic packages, e.g., nano-wafer-level packages. However, current experimental photo-mechanics techniques are often found to be insufficiently sensitive but also lacking in sufficient resolution to determine stress distributions of nanoscale electronic packages. In this study, the digital image speckle correlation method was combined with the atomic force microscopy (AFM) to develop a new experimental measurement technique, so-called nanodigital image speckle correlation (Nano-DiSC), for the determination of deformation on the nanometer scale. With the developed theoretical model, computational algorithms and nanospeckle pattern preparation method, the Nano-DiSC methodology was found to be able to measure the in-plane deformation on the sub-10 nm scale.
XPS STUDY OF DIAMOND-LIKE CARBON-BASED NANOCOMPOSITE FILMS
Authors: ZHANG S. , FU Y. Q. , BUI X. L. , DU H. J.
Published: May 2005

X-ray photoelectron spectroscopy (XPS) analysis of amorphous carbon ( a - C )-based nanocomposite films has been carried out. Four bonding types of carbon are revealed from the C 1s spectra: C – C sp 2 and sp 3 bonding, C – O and C – Ti bonding. With the introduction of Ti and Al into the a - C matrix, the carbon sp 3/ sp 2 ratio decreases significantly. XPS results also confirm that the Al doped in the film basically exists as an elemental Al in the a - C matrix, and the titanium is mostly bonded with carbon to form nc - TiC .
INVESTIGATION OF PECULIARITIES OF LIGHT SCATTERING BY NANOSTRUCTURAL CHANGES IN THE CRYSTAL LATTICE OF FERROELECTRIC BARIUM SODIUM NIOBATE CRYSTAL
Authors: IVANOVA S. V.
Published: May 2005

Thermal changes of light scattering images in the far-field were observed under steady illumination by an incident laser beam of finite beam width on barium sodium niobate crystals in the temperature range of 20–500°C. Different patterns of light scattering in far-field were observed — from striped to round-like form with dependence on temperature, conditions of grown, direction of beam and polarization. The round-like form was observed on cooling from 450°C to 240°C. Striped forms of light scattering were observed below 200°C. Correlation of the behavior of elastic light scattering was observed in this temperature range.
STUDIES ON GENERATION AND CHARACTERIZATION OF NANOALUMINA POWDER USING WIRE EXPLOSION TECHNIQUE
Authors: SARATHI R. , CHAKRAVARTHY S. R. , VENKATASESHAIAH C.
Published: May 2005

The nanoalumina particles were produced by the wire explosion process. The size and the shape of the particles were measured using Transmission Electron Microscope (TEM) studies. The Scanning Electron Microscope (SEM) studies were carried out to confirm that the particles are of sub-micron size. The compositions of the material were characterized through the Energy Dispersive Angle X-ray Analysis (EDAX) results. The Wide Angle X-ray Diffraction (WAXD) and the Fourier Transform Infra-Red (FTIR) results confirmed the nanosize powder formed by the process as crystalline γ- Al 2 O 3 powder. The thermal characteristics were analyzed using Thermo-gravimetric Differential thermal analysis (TG-DTA). It is identified that the local temperature of the medium at the time of formation of nanopowder decides the phase characteristics of the powder material. The formation mechanism of nanopowder by wire explosion technique was explained in detail. The mechanism of nanopowder formation and the characteristic changes that occur during the explosion process were recorded using a high-speed digital camera.
EFFECT OF NANOSIZED TiO2 POWDER ON PREPARATION AND PROPERTIES OF Ag-BASED ELECTRODE MATERIALS
Authors: JEONG SOON-JONG , KOH JUNG-HYUK , LEE DONG-YOON , LEE JAE-SEOK , HA MUN-SU , SONG JAE-SUNG , KIM MYOUNG-HO
Published: May 2005

This study presents the synthesis of nano-oxide-added Ag/Pd powders and its properties tolerable at temperatures above 1100°C for an electrode material utilized in multilayer ceramic devices. The powders of xAg/yPd powder around core cell TiO 2 were formed in a co-precipitation process of Ag and Pd in nano-oxide-dispersed solution, where Ag and Pd precursors are melted in HNO 3 acid. Reaction between ceramic and electrode layers with nanoparticle oxide powder allows internal stress to reduce and mechanical bonding strength to increase due to anchor effect. The densification of the nano-oxide-added electrode paste followed the TiO 2 solid state diffusion-controlled mechanism upon sintering process. The mechanical bonding strength and electrical conductivity were measured after sintering the electrode-printed sheets. As a result, very high adhesive strength over the piezoelectric ceramics' fracture strength and good electrical conductivity of more than 104/Ωcm could be obtained in the multilayer ferroelectric structure which is a form of stacking ceramics layer and electrode layer containing nanoparticles.
APPLICATION OF MICROTHERMAL ANALYSIS AND PULSED FORCE MICROSCOPY TO CHARACTERIZE NANOSTRUCTURED POLYMER
Authors: THOMPSON S. , DUTTA N. K. , ROY CHOUDHURY N.
Published: May 2005

In this investigation, we present the first results of Microthermal analysis (MicroTA) and Pulsed-Force-Mode (PFM) scanning force microscopy employed for visualization and characterization of nanostructured side-chain crystalline polymeric material. PFM was employed to clearly visualize the interesting self-organizing characteristics and the intimate contact of crystalline order as well as amorphous disorder in such polymer. As the sample was heated above the melting point, the well-defined crystalline regions observed at lower temperature no longer exist, and diffused melt boundaries are clearly observed using PFM. The nanophase separated system undergoes a sharp change in its adhesion and stiffness properties with temperature below and above the crystal melting point. Local thermal analyses using MicroTA exhibit consistent rapid crystal melting curves and its lateral homogeneity.
SYNTHESIS OF CARBON NANOTUBES BY ECR PLASMA-ASSISTED CHEMICAL VAPOR DEPOSITION
Authors: PATRA S. K. , MOHAN RAO G.
Published: May 2005

Carbon nanotubes have been grown using electron cyclotron resonance (ECR) plasma source at a substrate temperature of 500°C. Methane has been used as the source gas. A network of carbon nanotubes have been observed in Scanning Electron Microscopy (SEM). Transmission Electron Microscopy (TEM) revealed that the structure consists of straight, Y-junction and ring-like nanotubes. Further, electron diffraction (ED) of the nanotubes confirms graphite crystal structure.
CORROSION STUDY OF HARD DISKS BY OSA AND XPS
Authors: XU DAQING , LIU ERJIA , LIU BO , TAN HOOIIN , CHAN WENG-KONG , LING SHIH-FU
Published: May 2005

Perfluoropolyethers (PFPE) are most commonly employed as lubricants at head-disk interface in hard disk drives (HDD) to reduce friction and wear. Corrosion behavior is an important issue in high density magnetic recording disk-drives. The magnetic materials used in the magnetic storage layers as well as those used for making read–write transducers are not very corrosion resistant. In the presence of humidity and at elevated temperatures, corrosion occurs and materials from the magnetic layers and the NiP plating layers of the recording rigid media can migrate to the disk surfaces and form protrusions that are easily much larger than the head-disk clearances. As PFPE is sensitive to temperature, especially its mobile fraction, movement of the PFPE molecules will allow the magnetic media to be exposed to the environment through the micro pores existing in DLC overcoat, which will cause occurring of corrosion. In this paper, the corrosion characteristics of the magnetic media of the hard disks were analyzed using optical surface analyzer (OSA). X-ray photoelectron spectroscopy (XPS) was also used to characterize the distribution of the elements on the surfaces of hard disks. A relationship between heating time, lubricant layer thickness, number of corrosion spots and distribution of elements was attempted. It was found that the corrosion spots for the disks are related to the heating time. A small change in the thickness of lubricant layer can cause a drastic change in corrosion rate.
THE CONDUCTING HOMOGENEITY OF ITO ELECTRODE AND WATER-SOLUBLE CONDUCTING POLYANILINE FILMS
Authors: WU CHUN-GUEY , CHEN PI-YU , CHANG SU-SAN
Published: May 2005

The morphology and conductivity of indium/tin oxide (ITO) film have a large impact on the performance of light emitting diode (LED) devices using ITO as an anode. Atomic Force Microscope and current image tunneling spectroscopy (CITS) were used to probe the surface morphology and scanning tunneling spectroscopy (STS) of ITO surface. The morphology of all ITO films studied revealed a spherical aggregation with various grain sizes of 20~50 nm, depends on clean methods. It was also found that the conductivity of ITO films is related to film thickness. In general, thicker film shows higher conductivity. Nevertheless, the conductivity within a single grain is very homogeneous. On the other hand, the topographies of poly(N-(4-sulfophenyl)aniline (PSA) films revealed a rod-shaped aggregation with a diameter of 50 nm. The corresponding CITS images revealed conducting islands with irregular shape and size. The conductivity within a single polymer rod is not homogeneous.
THE SCANNING TIP MICROWAVE NEAR-FIELD MICROSCOPY OF FERROELECTROMAGNETIC Pb(Fe1/2Nb1/2)O3 CRYSTALS
Authors: YANG Y. , ZHANG S. T. , HUANG H. B. , LIU J.-M. , LIU Z. G.
Published: May 2005

Scanning tip near-field microwave microscope (STMNM) was employed to obtain the nanoscale dielectric constant profile of Pb ( Fe 1/2 Nb 1/2) O 3 (PFN) single crystal. The observed pseudo-periodic profiles of the dielectric constant indicate the existence of ferroelectric domains. The low dielectric constant area is supposed to have some relation with the antiferromagnetic property of PFN and the appearance of magnetic hysteresis below the Néel temperature implies the formation of magnetic order. The Mössbauer spectra show that the iron ions are in trivalence high spin state. The appearance of the sextet confirms the magnetic order existed in PFN under its Néel temperature.
SELF-ASSEMBLED METAL QUANTUM DOTS
Authors: CHEN L. J. , SU P. Y. , LIANG J. M. , HU J. C. , WU W. W. , CHENG S. L.
Published: May 2005

Long-range order of uniform in size and regular in shape 2D arrays of Au@TOAB-DT nanoparticles (4.9 nm) were formed by a displacement reaction of the outer-shells from tetraoctylammonium bromide (TOAB) to dodecanethiol (DT) molecules at room temperature. The displacement reaction has utilized both superior size and shape control of Au@TOAB nanoparticles and uniform dispersion capability of Au@DT nanoparticles to achieve an extraordinarily large in extent (3 μ m × 3 μ m ) regular nanoparticle lattice structure.

Self-assembled NiSi quantum dot arrays have been grown on relaxed epitaxial Si 0.7 Ge 0.3 on (001) Si . The formation of the one-dimensional ordered structure is attributed to the nucleation of NiSi nanodots on the surface undulations induced by step bunching on the surface of SiGe film owing to the miscut of the wafers from normal to the (001) Si direction. The two-dimensional, pseudo-hexagonal structure was achieved under the influence of repulsive stress between nanodots.
MICROSTRUCTURE STUDY OF ROD-LIKE NANOCRYSTALLINE RUTILE TiO2 SYNTHESIZED BY SONOCHEMICAL METHOD
Authors: ZHU J. M. , HUANG S. S. , MA G. B. , ZHU X. H. , ZHOU S. H. , MING N. B.
Published: May 2005

Rutile TiO 2 nanorods have been successfully prepared by a sonochemical method. The microstructures of TiO 2 nanorods were investigated in detail by transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HREM). Probable mechanisms for the sonochemical formation of TiO 2 nanorods are proposed.
A REGIONAL COMPARISON OF THE MOTIVATION AND PROBLEMS OF VIETNAMESE ENTREPRENEURS
Authors: BENZING CYNTHIA , CHU HUNG MANH , CALLANAN GERARD
Published: May 2005

This study assesses the motivations, perceived success factors and business problems experienced by entrepreneurs in Vietnam. It also compares the results between the northern and southern regions of the country. Using data from a survey of 378 Vietnamese entrepreneurs in Hanoi and Ho Chi Minh City, results show that Vietnamese entrepreneurs are motivated by the ability to provide jobs for themselves and family members, to gain public recognition, and to prove they can successfully run a business of their own. Important perceived entrepreneurial success factors include friendliness toward customers and a good product at a good price while significant business problems include too much competition, unreliable employees and the inability to obtain both short-term and long-term capital. Results also show a number of city/regional differences in motivation, success factors and perceived success. Implications for policymakers in Vietnam and other emerging economies are also presented.
AMP-activated protein kinase kinase activity and phosphorylation of AMP-activated protein kinase in contracting muscle of sedentary and endurance-trained rats
Authors: Hurst Denise , Taylor Eric B. , Cline Troy D. , Greenwood Lyle J. , Compton Cori L. , Lamb Jeremy D. , Winder William W.
Published: May 2005

This study was designed to examine activity of AMP-activated protein kinase kinase (AMPKK) in muscles from nontrained and endurance-trained rats. Rats were trained 5 days/wk, 2 h/day for 8 wk at a final intensity of 32 m/min up a 15% grade with 30-s sprints at 53 m/min every 10 min. Gastrocnemius muscles were stimulated in situ in trained and nontrained rats for 5 min at frequencies of 0.4/s and 1/s. Gastrocnemius LKB1 protein, a putative component of the AMPKK complex (LKB1, STRAD, and MO25), increased approximately twofold in response to training. Phosphorylation of AMP-activated protein kinase (AMPK) determined by Western blot and AMPK activity of immunoprecipitates (both isoforms) was increased at both stimulation rates in both trained and nontrained muscles. AMPKK activity was 73% lower in resuspended polyethylene glycol precipitates of muscle extracts from the trained compared with nontrained rats. AMPKK activity did not increase in either trained or nontrained muscle in response to electrical stimulation, even though phospho-AMPK did increase. These results suggest that AMPKK is activated during electrical stimulation of both trained and nontrained muscle by mechanisms other than covalent modification.
Cholinergic agonist-induced pepsinogen secretion from murine gastric chief cells is mediated by M1and M3muscarinic receptors
Authors: Xie Guofeng , Drachenberg Cinthia , Yamada Masahisa , Wess Jürgen , Raufman Jean-Pierre
Published: June 2005

Muscarinic cholinergic mechanisms play a key role in stimulating gastric pepsinogen secretion. Studies using antagonists suggested that the M3receptor subtype (M3R) plays a prominent role in mediating pepsinogen secretion, but in situ hybridization indicated expression of M1receptor (M1R) in rat chief cells. We used mice that were deficient in either the M1(M1R−/−) or M3(M3R−/−) receptor or that lacked both receptors (M1/3R−/−) to determine the role of M1R and M3R in mediating cholinergic agonist-induced pepsinogen secretion. Pepsinogen secretion from murine gastric glands was determined by adapting methods used for rabbit and rat stomach. In wild-type (WT) mice, maximal concentrations of carbachol and CCK caused a 3.0- and 2.5-fold increase in pepsinogen secretion, respectively. Maximal carbachol-induced secretion from M1R−/−mouse gastric glands was decreased by 25%. In contrast, there was only a slight decrease in carbachol potency and no change in efficacy when comparing M3R−/−with WT glands. To explore the possibility that both M1R and M3R are involved in carbachol-mediated pepsinogen secretion, we examined secretion from glands prepared from M1/3R−/−double-knockout mice. Strikingly, carbachol-induced pepsinogen secretion was nearly abolished in glands from M1/3R−/−mice, whereas CCK-induced secretion was not altered. In situ hybridization for murine M1R and M3R mRNA in gastric mucosa from WT mice revealed abundant signals for both receptor subtypes in the cytoplasm of chief cells. These data clearly indicate that, in gastric chief cells, a mixture of M1and M3receptors mediates cholinergic stimulation of pepsinogen secretion and that no other muscarinic receptor subtypes are involved in this activity. The development of a murine secretory model facilitates use of transgenic mice to investigate the regulation of pepsinogen secretion.
Mechanisms of mechanotransduction by specialized low-threshold mechanoreceptors in the guinea pig rectum
Authors: Zagorodnyuk Vladimir P. , Lynn Penny , Costa Marcello , Brookes Simon J. H.
Published: June 2005

The guinea pig rectum, but not the colon, is innervated by a specialized class of distension-sensitive mechanoreceptors that have transduction sites corresponding to rectal intraganglionic laminar endings (rIGLEs). Rectal mechanoreceptors recorded in vitro had low threshold to circumferential stretch, adapted slowly, and could respond within 2 ms to mechanical stimulation by a piezo-electric probe. Antagonists to ionotropic N-methyl-d-aspartate (NMDA; CGS 19755, memantine) and non-NMDA (6,7-dinitroquinoxaline-2,3-dione) glutamate receptors did not affect mechanotransduction. In normal Krebs solution, the P2X purinoreceptor agonist α,β-methylene ATP reduced mechanoreceptor firing evoked by distension but simultaneously relaxed circular smooth muscle and inhibited stretch-induced contractions. Neither ATP nor α,β-methylene ATP affected mechanotransduction when transduction sites were directly compressed with von Frey hairs. The P2 purinoreceptor antagonist pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid did not affect stretch-induced firing but reduced the inhibitory effect of α,β-methylene ATP on stretch-induced firing. Under isometric conditions, blocking synaptic transmission in Ca2+-free solution reduced stretch-evoked firing but not when basal tension was restored to control levels. Under isotonic condition, Ca2+-free solution did not significantly affect load-evoked firing. The blockers of mechanogated and/or transient receptor potential channels, benzamil, Gd3+, SKF 96365, and ruthenium red inhibited stretch-induced firing but, in parallel, significantly reduced stretch-induced contractions. Benzamil and SKF 96365 were able to inhibit mechanotransduction when transduction sites were compressed with von Frey hairs. The results show that mechanotransduction is rapid but does not depend on fast exocytotic release of mediators. It is likely that stretch-activated ion channels on rIGLEs are involved in direct, physical mechanotransduction by rectal low-threshold mechanoreceptors.
Steady-state effects of temperature acclimation on the transcriptome of the rainbow trout heart
Authors: Vornanen Matti , Hassinen Minna , Koskinen Heikki , Krasnov Aleksei
Published: June 2005

Cold-acclimated (CA) phenotype of trout heart was induced by 4-wk acclimation at 4°C and was characterized by 32.7% increase in relative heart mass and 49.8% increase in ventricular myocyte size compared with warm-acclimated (WA; 18°C) fish ( P < 0.001). Effect of temperature acclimation on transcriptome of the rainbow trout heart was examined using species-specific microarray chips containing 1,380 genes. After 4 wk of temperature acclimation, 8.8% (122) of the genes were differently expressed in CA and WA hearts, and most of them (82%) were upregulated in the cold ( P < 0.01). Transcripts of genes engaged in protein synthesis and intermediary metabolism were most strongly upregulated, whereas genes contributing to the connective tissue matrix were clearly repressed. Extensive upregulation of the genes coding for ribosomal proteins and translation elongation and initiation factors suggest that the protein synthesis machinery of the trout heart is enhanced in the cold and is an essential part of the compensatory mechanism causing and maintaining the hypertrophy of cardiac myocytes. The prominent depression of collagen genes may be indicative of a reduced contribution of extracellular matrix to the remodeling of the CA fish heart. Temperature-related changes in transcripts of metabolic enzymes suggest that at mRNA level, glycolytic energy production from carbohydrates is compensated in the heart of CA rainbow trout, while metabolic compensation is absent in mitochondria. In addition, the analysis revealed three candidate genes: muscle LIM protein, atrial natriuretic peptide B, and myosin light chain 2, which might be central for induction and maintenance of the hypertrophic phenotype of the CA trout heart. These findings indicate that extensive modification of gene expression is needed to maintain the temperature-specific phenotype of the fish heart.
Temperature-dependent skeletal muscle dysfunction in rats with congestive heart failure
Authors: Thorud H.-M. Schiøtz , Verburg E. , Lunde P. K. , Strømme T. A. , Sjaastad I. , Sejersted O. M.
Published: June 2005

Abnormalities in the excitation-contraction coupling of slow-twitch muscle seem to explain the slowing and increased fatigue observed in congestive heart failure (CHF). However, it is not known which elements of the excitation-contraction coupling might be affected. We hypothesize that the temperature sensitivity of contractile properties of the soleus muscle might be altered in CHF possibly because of alterations of the temperature sensitivity of intracellular Ca2+handling. We electrically stimulated the in situ soleus muscle of anesthetised rats that had 6-wk postinfarction CHF using 1 and 50 Hz and using a fatigue protocol (5-Hz stimulation for 30 min) at 35, 37, and 40°C. Ca2+uptake and release were measured in sarcoplasmic reticulum vesicles at various temperatures. Contraction and relaxation rates of the soleus muscle were slower in CHF than in sham at 35°C, but the difference was almost absent at 40°C. The fatigue protocol revealed that force development was more temperature sensitive in CHF, whereas contraction and relaxation rates were less temperature sensitive in CHF than in sham. The Ca2+uptake and release rates did not correlate to the difference between CHF and sham regarding contractile properties or temperature sensitivity. In conclusion, the discrepant results regarding altered temperature sensitivity of contraction and relaxation rates in the soleus muscle of CHF rats compared with Ca2+release and uptake rates in vesicles indicate that the molecular cause of slow-twitch muscle dysfunction in CHF is not linked to the intracellular Ca2+cycling.
Homeostatic responses to caloric restriction: influence of background metabolic rate
Authors: Evans S. A. , Parsons A. D. , Overton J. M.
Published: June 2005

The biological responses to caloric restriction (CR) are generally examined in rats with elevated metabolic rates due to being housed at ambient temperatures (Ta) below the zone of thermoneutrality. We determined the physiological and behavioral responses to 2 wk of 30–40% CR in male FBNF1 rats housed in cool (Ta = 12°C) or thermoneutral (TMN; Ta = 30°C) conditions. Rats were instrumented with telemetry devices and housed continuously in home-cage calorimeters for the entire experiment. At baseline, rats housed in cool Ta had reduced rate of weight gain; thus a mild CR (5%) group at thermoneutrality for weight maintenance was also studied. Rats housed in cool Ta exhibited elevated caloric intake (cool = 77 ± 1; TMN = 54 ± 2 kcal), oxygen consumption (V̇o2; cool = 9.9 ± 0.1; TMN = 5.5 ± 0.1 ml/min), mean arterial pressure (cool = 103 ± 1; TMN = 80 ± 2 mmHg), and heart rate (cool = 374 ± 3; TMN = 275 ± 4 beats/min). Cool-CR rats exhibited greater CR-induced weight loss (cool = −62 ± 3; TMN = −42 ± 3 g) and reductions in V̇o2 (cool = −2.6 ± 0.1; TMN = −1.5 ± 0.1 ml/min) but similar CR-induced reductions in heart rate (cool = −59 ± 1; TMN= −51 ± 7 beats/min). CR had no effect on arterial blood pressure or locomotor activity in either group. Unexpectedly, weight maintenance produced significant reductions in V̇o2 and heart rate. At thermoneutrality, a single day of refeeding effectively abolished CR-induced reductions in V̇o2 and heart rate. The results reveal that rats with low or high baseline metabolic rate exhibit comparable compensatory reductions in V̇o2 and heart rate and suggest that Ta can be used to modulate the metabolic background on which the more prolonged effects of CR can be studied.
The Human Spiral Ganglion: New Insights into Ultrastructure, Survival Rate and Implications for Cochlear Implants
Authors: Glueckert Rudolf , Pfaller Kristian , Kinnefors Anders , Rask-Andersen Helge , Schrott-Fischer Anneliese
Published: May 2005

This study was based on high-resolution SEM assessment of freshly fixed, normal-hearing, human inner ear tissue. In addition, semiquantitative observations were made in long-term deafened temporal bone material, focusing on the spiral ganglia and nerve projections, and a detailed study of the fine bone structure in macerated tissues was performed. Our main findings detail the presence of extensive bony fenestrae surrounding the nerve elements, permitting a relatively free flow of perilymph to modiolar structures. The clustering of the spiral ganglion cells in Rosenthal’s canal and the detailed and intricate course of postganglionic axons are described. The close proximity of fibers to cell soma is demonstrated by impression in cell surfaces, and presence of small microvilli-like structures at the contact regions, anchoring nerve fibers to the cell wall. Extensive fenestrae and the presence of a fragile network of endosteal bony structures at the surfaces guiding nerve fibers are described in detail for the first time. This unique freshly prepared human material offers the opportunity for a detailed ultrastructural study not previously possible on postmortem fixed material and more accurate information to model electrostimulation of the human auditory nerve through a cochlear implant. On the basis of this study, we suggest that the concentration and high density of spiral ganglion cells, and the close physical interaction between neural elements, may explain the slow retrograde degeneration found in humans after loss of peripheral receptors. Moreover, the fragile bony columns connecting the spiral canal with the osseous spiral lamina may be a potential site for trauma in (perimodiolar) electrode positioning.
Pathophysiological Role of Vascular Endothelial Growth Factor in the Remnant Kidney
Authors: Schrijvers Bieke F. , Flyvbjerg Allan , Tilton Ronald G. , Rasch Ruth , Lameire Norbert H. , De Vriese An S.
Published: May 2005

Background: Subtotal renal ablation is characterized by initial glomerular hypertrophy, followed by progressive development of glomerulosclerosis and interstitial fibrosis. Vascular endothelial growth factor (VEGF) is involved in glomerular hypertrophy and dysfunction in several pathophysiological conditions. On the other hand, progressive glomerulosclerosis and tubulo-interstitial fibrosis in the remnant kidney have been associated with loss of VEGF expression. Methods: To explore the pathophysiological role of VEGF in the development of glomerular hypertrophy and renal damage in the remnant kidney model, we examined the effect of a neutralizing VEGF antibody on glomerular volume and kidney function in rats after subtotal nephrectomy or sham operation. Erythropoietin was administered to exclude a confounding effect of anaemia. Results: Six weeks after subtotal nephrectomy, plasma urea and creatinine concentrations, urinary albumin excretion, and mean glomerular volume were elevated in the placebo-treated uraemic rats as compared with the sham-operated rats. Inhibition of VEGF partially prevented the glomerular hypertrophy and largely prevented the rise in urinary albumin excretion, but did not affect creatinine clearance in uraemic rats. Conclusions: VEGF is a mediator of glomerular hypertrophy after subtotal renal ablation. In view of glomerular hypertrophy as the initial deleterious event ultimately leading to progressive glomerulosclerosis, agents that block this glomerular growth could be useful in preventing scarring in progressive renal disease.
Kidney Expression of RhoA, TGF-β1, and Fibronectin in Human IgA Nephropathy
Authors: Mattii Letizia , Segnani Cristina , Cupisti Adamasco , D’Alessandro Delfo , Moscato Stefania , Meola Mario , Barsotti Giuliano , Marinò Michele , Bianchi Francesco , Dolfi Amelio , Bernardini Nunzia
Published: May 2005

Background: The Rho/transforming growth factor-β (TGF-β) system plays a crucial role in the progression of renal damage due to stimulation of extracellular matrix molecule deposition. In fact, the in vitro TGF-β-mediated production of fibronectin, one of the major TGF-β-regulated extracellular components, has recently been correlated with Rho protein signalling molecules. Although a close relationship between increased renal tissue levels of TGF-β1 and fibronectin has been reported in IgA nephropathy, no data are available on renal tissue expression of Rho proteins. Methods: This study was designed to assess in IgA nephropathy patients the kidney tissue immunohistochemical expression of RhoA, TGF-β1, and fibronectin, and the rate of immunoreactivity for each antigen by image analysis. Results: An increase in RhoA, TGF-β1, and fibronectin expression was detected in tubulointerstitium and in glomeruli of IgA nephropathy compared to normal kidneys; in particular, RhoA was found also in proximal tubules, unlike control kidneys and mainly at the cell boundary level, which is in keeping with its activated form. The image analysis confirmed that the kidney tissue levels of RhoA, TGF-β1, and fibronectin were significantly enhanced in the patients. Conclusion: This study suggests that RhoA may represent a key molecule in the signalling transduction pathway of profibrotic signals in IgA nephropathy.