bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Contact—Its Significance for Multiphase Heat Transfer: Diverse Examples
Authors: Chen John C.
Published: July 2003

The nature and dynamics of surface contacts often govern heat transfer in multiphase systems. Physical scale, time scale, and intermolecular forces all affect basic mechanisms of transport between the multiphase medium and a submerged surface. Parameters in one or more of these domains can be the determining factor for transfer rate and efficiency, depending on the specific application. Research results for systems as diverse as fluidized particles and condensing liquids are examined to illustrate this significance. Specifically, it is shown that for heat transfer to/from surfaces submerged in bubbling fluidized beds, parameters in time domain are most important. In the case of condensation, it is shown that substantial enhancement of heat transfer coefficient can be obtained by controlling parameters in the domain of surface free energies.
Temperature Dependence of Thermal Conductivity Enhancement for Nanofluids
Authors: Das Sarit Kumar , Putra Nandy , Thiesen Peter , Roetzel Wilfried
Published: July 2003

Usual heat transfer fluids with suspended ultra fine particles of nanometer size are named as nanofluids, which have opened a new dimension in heat transfer processes. The recent investigations confirm the potential of nanofluids in enhancing heat transfer required for present age technology. The present investigation goes detailed into investigating the increase of thermal conductivity with temperature for nano fluids with water as base fluid and particles of Al2O3 or CuO as suspension material. A temperature oscillation technique is utilized for the measurement of thermal diffusivity and thermal conductivity is calculated from it. The results indicate an increase of enhancement characteristics with temperature, which makes the nanofluids even more attractive for applications with high energy density than usual room temperature measurements reported earlier.
Swirling Effect on Thermal-Fluid Transport Phenomena in a Strongly Heated Concentric Annulus
Authors: Torii Shuichi , Yang Wen-Jei
Published: July 2003

A numerical study is performed to investigate thermal transport phenomena in circular Couette flow in a concentric annulus, in which an axially rotating inner cylinder and stationary outer cylinder are strongly heated under the same heat flux condition. The anisotropic t2¯-εt heat-transfer model together with the anisotropic k-ε turbulence model is employed to determine thermal eddy diffusivity. When the inner cylinder is at rest, the turbulent kinetic energy and temperature variance substantially diminish over the whole annular cross-section along the flow, resulting in laminarization, i.e., a deterioration in heat-transfer performance at the inner and outer cylinder walls. In contrast, a substantial reduction in the turbulent kinetic energy and temperature variance in the laminarizing flow is suppressed in the presence of inner core rotation. In other words, inner core rotation contributes to the suppression of laminarization in a strongly heated gas flow. These characteristics in thermal fluid flow with temperature-dependent thermal property are summarized in the form of dimensionless heat flux parameter versus inlet Reynolds number with the Taylor number, as the parameter.
The Performances of Internal Helical-Rib Roughness Tubes Under Fouling Conditions: Practical Cooling Tower Water Fouling and Accelerated Particulate Fouling
Authors: Li Wei
Published: July 2003

This paper addresses fouling in a family of seven copper helically ribbed tubes. Series of semi-theoretical linear fouling correlations for long term combined precipitation and particulate fouling (PPF) in cooling tower systems and for accelerated particulate fouling were developed.
Laminar Natural Convection Heat Transfer in a Differentially Heated Square Cavity Due to a Thin Fin on the Hot Wall
Authors: Shi Xundan , Khodadadi J. M.
Published: July 2003

A finite-volume-based computational study of steady laminar natural convection (using Boussinesq approximation) within a differentially heated square cavity due to the presence of a single thin fin is presented. Attachment of highly conductive thin fins with lengths equal to 20, 35 and 50 percent of the side, positioned at 7 locations on the hot left wall were examined for Ra=104,105,106, and 107 and Pr=0.707 (total of 84 cases). Placing a fin on the hot left wall generally alters the clockwise rotating vortex that is established due to buoyancy-induced convection. Two competing mechanisms that are responsible for flow and thermal modifications are identified. One is due to the blockage effect of the fin, whereas the other is due to extra heating of the fluid that is accommodated by the fin. The degree of flow modification due to blockage is enhanced by increasing the length of the fin. Under certain conditions, smaller vortices are formed between the fin and the top insulated wall. Viewing the minimum value of the stream function field as a measure of the strength of flow modification, it is shown that for high Rayleigh numbers the flow field is enhanced regardless of the fin’s length and position. This suggests that the extra heating mechanism outweighs the blockage effect for high Rayleigh numbers. By introducing a fin, the heat transfer capacity on the anchoring wall is always degraded, however heat transfer on the cold wall without the fin can be promoted for high Rayleigh numbers and with the fins placed closer to the insulated walls. A correlation among the mean Nu, Ra, fin’s length and its position is proposed.
Correction for Exponential Dependence of Viscosity on Temperature for Natural Convection by an Integral Method
Authors: Burmeister Louis C.
Published: July 2003

It is common to correct for the effect of exponential dependence on inverse absolute temperature of the viscosity on the Nusselt number for laminar natural convection by multiplying the correlation for constant properties by a factor μ∞/μwn to obtain Nu=C Ra1/4μ∞/μwn. That there is a sound basis for the functional form of this corrective term is newly shown by employing an integral method to obtain closed-form solutions to the laminar boundary-layer equations for the case of a vertical plate of specified temperature immersed in such a liquid. The basis for the alternative means of correction by using the correlation for constant properties with viscosity evaluated at a special reference temperature is also shown.
By-Pass Air-Valve Control of an OWC Wave Power Plant
Authors: de O. Falca˜o A. F. , Vieira L. C. , Justino P. A. P. , Andre´ J. M. C. S.
Published: July 2003

The paper deals with the numerical simulation of the performance of an oscillating-water-column (OWC) wave power plant equipped with a by-pass valve whose role is to prevent the turbine flow rate from exceeding the stall-free operating conditions. Continuous and step-wise valve area changes are considered, the second case corresponding to multi-element design. The adequacy of the valve and of its control is assessed through the gain in annual electrical energy and the total number of required valve strokes. The following items are separately analyzed: (i) number of (identical) valve elements; (ii) valve response time; (iii) signal noise level in chamber air-pressure measurements due to large-eddy turbulence; (iv) valve’s control algorithm.
Probability Distributions of Wave Heights and Periods in Measured Combined Sea-States from the Portuguese Coast
Authors: Guedes Soares C. , Carvalho A. N.
Published: July 2003

An analysis is made of measured two-peaked sea spectra from a deep-water location at the Portuguese Coast. The spectra are organized in different groups according to the relative nature of their two component wave systems. The probability distributions of wave height and period are determined and compared with several theoretical models.
Polynomial Approximations of Wave Loading and Superharmonic Responses of Fixed Structures
Authors: Liaw Chih Young , Zheng Xiang Yuan
Published: July 2003

Besides the commonly considered drag force, inundation due to variable water surface is another important nonlinear effect of wave loading. Quadratic and quartic approximations of the inundation drag force are derived using the least squares method. Other nonlinear effects, including the second-order wave kinematics and nonlinear inertia wave forces, are also considered. Superharmonic forces and the corresponding structural responses due to different nonlinear effects are compared using a single mode representation of the fixed offshore structural system. The appropriate expressions that can serve as the basis for the Volterra series representation of the nonlinear wave forces are presented.
Full Dynamic Analysis of Offshore Platform Structures Using Exact Timoshenko Pipe Element
Authors: Horr A. M. , Safi M.
Published: July 2003

One of the major divisions in the mathematical modeling of a tubular structure is to include the effect of the transverse shear stress and rotary inertia in vibration of members. During the past three decades, problems of vibration of tubular structures have been considered by some authors, and special attention has been devoted to the Timoshenko theory. There have been considerable efforts, also, to apply the method of spectral analysis to vibration of a structure with tubular section beams. The purpose of this paper is to compare the results of the improved complex spectral element method for the Timoshenko theory with those derived from the conventional finite element method for an offshore structure. Using a computer program, the proposed formulation has been extended to derive the dynamic response of an offshore platform structure under dynamic loads.
Nonlinear Impact Loading in an Oblique Seaway
Authors: Finn Patrick J. , Beck Robert F. , Troesch Armin W. , Shin Yung Sup
Published: July 2003

There is an increasing interest in developing direct calculation methods and procedures for determining extreme wave loads on ship girders (e.g. ISSC, 2000 [1]). Ships experiencing bottom and bow flare slamming have heightened the need for computational tools suitable to accurately predict motion and structural responses. The associated nonlinear impact problem is complicated by the complex free surface and body boundary conditions. This paper examines a “blended” linear–nonlinear method by which extreme loads due to bottom impact and flare slamming can be determined. Using a high-speed container ship as an example, comparisons of motions, shear and bending moments, and pressures are made in head and oblique bow-quartering waves. The time-domain computer program used in the comparison is based upon partially nonlinear models. The program, NSHIPMO, is an blended strip theory method using “impact” stations over the forward part of the ship and partially nonlinear stations over the rest. Body exact hydrostatics and Froude-Krylov excitation are used over the entire hull. The impact theory of Troesch and Kang [2] is employed to estimate the sectional nonlinear impact forces acting upon the specified nonlinear sections, while the linear theory of Salvesen et al. (STF) [3] is used to blend the remainder of the hydrodynamic forces, that is the radiation and diffraction components. Results from the simulation are presented with discussions of accuracy and time of computation. Several issues associated with the blended nonlinear time-domain simulation are presented, including modeling issues related to directional yaw-sway control and a vertical plane dynamic instability in long waves that has not previously been recognized.
Experimental and Theoretical Modeling of the Effective Thermal Conductivity of Rough Steel Spheroid Packed Beds
Authors: Buonanno G. , Carotenuto A. , Giovinco G. , Massarotti N.
Published: July 2003

The upper and lower bounds of the effective thermal conductivity of packed beds of rough spheres are evaluated using the theoretical approach of the elementary cell for two-phase systems. The solid mechanics and thermal problems are solved and the effects of roughness and packed bed structures are also examined. The numerical solution of the thermal conduction problem through the periodic regular arrangement of steel spheroids in air is determined using the Finite Element Method. The numerical results are compared with those obtained from an experimental apparatus designed and built for this purpose.
Thermosolutal Convection in a Partly Porous Vertical Annular Cavity
Authors: Benzeghiba M. , Chikh S. , Campo A.
Published: July 2003

Numerical solutions for thermosolutal convection in a vertical concentric cavity partly filled with a porous medium are presented in this paper. The cavity is subject to pre-selected horizontal temperature and concentration gradients. The general Brinkman-Forchheimer-extended Darcy model is adopted to formulate the fluid flow through the porous matrix in the cavity. The effects of the controlling parameters on the flow patterns and heat and mass transfer behavior are thoroughly documented. Different flow structures are produced in the course of the computations, which respond to the geometric parameters, fluid nature, thermofluid dynamic parameters and porous matrix characteristics. The collection of numerical results elucidates that the double diffusion zone varies and, besides it is strongly dependent on the coupling between the Prandtl and Lewis numbers. Moreover, the variations of the Sherwood number show the presence of an extended range of double diffusion phenomena within the conditions pertinent to Darcian flow at Da=10−5. It has been discovered that a partly porous annular cavity is more efficient than a fully porous annular cavity. This aspect may have a beneficial impact on engineering applications in the areas of filtration and thermal insulation.
Programmed Adsorption and Release of Proteins in a Microfluidic Device
Authors: Huber Dale L. , Manginell Ronald P. , Samara Michael A. , Kim Byung-Il , Bunker Bruce C.
Published: July 2003

A microfluidic device has been developed that can adsorb proteins from solution, hold them with negligible denaturation, and release them on command. The active element in the device is a 4-nanometer-thick polymer film that can be thermally switched between an antifouling hydrophilic state and a protein-adsorbing state that is more hydrophobic. This active polymer has been integrated into a microfluidic hot plate that can be programmed to adsorb and desorb protein monolayers in less than 1 second. The rapid response characteristics of the device can be manipulated for proteomic functions, including preconcentration and separation of soluble proteins on an integrated fluidics chip.
Negligible Effect of Ions on the Hydrogen-Bond Structure in Liquid Water
Authors: Omta Anne Willem , Kropman Michel F. , Woutersen Sander , Bakker Huib J.
Published: July 2003

The effects of ions on bulk properties of liquid water, such as viscosity, have suggested that ions alter water's hydrogen-bonding network. We measured the orientational correlation time of water molecules in Mg(ClO
4
)
2
, NaClO
4
, and Na
2
SO
4
solutions by means of femtosecond pump-probe spectroscopy. The addition of ions had no influence on the rotational dynamics of water molecules outside the first solvation shells of the ions. This result shows that the presence of ions does not lead to an enhancement or a breakdown of the hydrogen-bond network in liquid water.
Hox10
and
Hox11
Genes Are Required to Globally Pattern the Mammalian Skeleton
Authors: Wellik Deneen M. , Capecchi Mario R.
Published: July 2003

Mice in which all members of the
Hox10
or
Hox11
paralogous group are disrupted provide evidence that these
Hox
genes are involved in global patterning of the axial and appendicular skeleton. In the absence of
Hox10
function, no lumbar vertebrae are formed. Instead, ribs project from all posterior vertebrae, extending caudally from the last thoracic vertebrae to beyond the sacral region. In the absence of
Hox11
function, sacral vertebrae are not formed and instead these vertebrae assume a lumbar identity. The redundancy among these paralogous family members is so great that this global aspect of
Hox
patterning is not apparent in mice that are mutant for five of the six paralogous alleles.
From Tides to Mixing Along the Hawaiian Ridge
Authors: Rudnick Daniel L. , Boyd Timothy J. , Brainard Russell E. , Carter Glenn S. , Egbert Gary D. , Gregg Michael C. , Holloway Peter E. , Klymak Jody M. , Kunze Eric , Lee Craig M. , Levine Murray D. , Luther Douglas S. , Martin Joseph P. , Merrifield Mark A. , Moum James N. , Nash Jonathan D. , Pinkel Robert , Rainville Luc , Sanford Thomas B.
Published: July 2003

The cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing. We investigated this cascade along the Hawaiian Ridge using observations and numerical models. A divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models. Large internal tidal waves with peak-to-peak amplitudes of up to 300 meters occur on the ridge. Internal-wave energy is enhanced, and turbulent dissipation in the region near the ridge is 10 times larger than open-ocean values. Given these major elements in the tides-to-turbulence cascade, an energy budget approaches closure.
The Segmentation Clock: Converting Embryonic Time into Spatial Pattern
Authors: Pourquié Olivier
Published: July 2003

In most animal species, the anteroposterior body axis is generated by the formation of repeated structures called segments. In vertebrate segmentation, a specialized mesodermal structure called the somite gives rise to skeletal muscles, vertebrae, and some dermis. Formation of the somites is a rhythmic process that involves an oscillator—the segmentation clock— driven by Wnt and Notch signaling. The clock ticks in somite precursors and halts when they reach a specific maturation stage defined as the wavefront, established by fibroblast growth factor and Wnt signaling. This process converts the temporal oscillations into the periodic spatial pattern of somite boundaries. The study of somite development provides insights into the spatiotemporal integration of signaling systems in the vertebrate embryo.
Lateralized Cognitive Processes and Lateralized Task Control in the Human Brain
Authors: Stephan Klaas E. , Marshall John C. , Friston Karl J. , Rowe James B. , Ritzl Afra , Zilles Karl , Fink Gereon R.
Published: July 2003

The principles underlying human hemispheric specialization are poorly understood. We used functional magnetic resonance imaging of letter and visuospatial decision tasks with identical word stimuli to address two unresolved problems. First, hemispheric specialization depended on the nature of the task rather than on the nature of the stimulus. Second, analysis of frontal candidate regions for cognitive control showed increased coupling between left anterior cingulate cortex (ACC) and left inferior frontal gyrus during letter decisions, whereas right ACC showed enhanced coupling with right parietal areas during visuospatial decisions. Cognitive control is thus localized in the same hemisphere as task execution.
CD46 in Meningococcal Disease
Authors: Johansson Linda , Rytkönen Anne , Bergman Peter , Albiger Barbara , Källström Helena , Hökfelt Tomas , Agerberth Birgitta , Cattaneo Roberto , Jonsson Ann-Beth
Published: July 2003

The human-specific bacterial pathogen
Neisseria meningitidis
is a major cause of sepsis and/or meningitis. The pili of
N. meningitidis
interact with CD46, a human cell-surface protein involved in regulation of complement activation. Transgenic mice expressing human CD46 were susceptible to meningococcal disease, because bacteria crossed the blood-brain barrier in these mice. Development of disease was more efficient with piliated bacteria after intranasal, but not intraperitoneal, challenge of CD46 transgenic mice, suggesting that human CD46 facilitates pilus-dependent interactions at the epithelial mucosa. Hence, the human CD46 transgenic mice model is a potentially useful tool for studying pathogenesis and for vaccine development against meningococcal disease.
Electrical Manipulation of Magnetization Reversal in a Ferromagnetic Semiconductor
Authors: Chiba D. , Yamanouchi M. , Matsukura F. , Ohno H.
Published: July 2003

We report electrical manipulation of magnetization processes in a ferromagnetic semiconductor, in which low-density carriers are responsible for the ferromagnetic interaction. The coercive force
H
C
at which magnetization reversal occurs can be manipulated by modifying the carrier density through application of electric fields in a gated structure. Electrically assisted magnetization reversal, as well as electrical demagnetization, has been demonstrated through the effect. This electrical manipulation offers a functionality not previously accessible in magnetic materials and may become useful for reversing magnetization of nanoscale bits for ultrahigh-density information storage.
Role of Adaptor TRIF in the MyD88-Independent Toll-Like Receptor Signaling Pathway
Authors: Yamamoto Masahiro , Sato Shintaro , Hemmi Hiroaki , Hoshino Katsuaki , Kaisho Tsuneyasu , Sanjo Hideki , Takeuchi Osamu , Sugiyama Masanaka , Okabe Masaru , Takeda Kiyoshi , Akira Shizuo
Published: July 2003

Stimulation of Toll-like receptors (TLRs) triggers activation of a common MyD88-dependent signaling pathway as well as a MyD88-independent pathway that is unique to TLR3 and TLR4 signaling pathways leading to interferon (IFN)-β production. Here we disrupted the gene encoding a Toll/IL-1 receptor (TIR) domain-containing adaptor, TRIF. TRIF-deficient mice were defective in both TLR3- and TLR4-mediated expression of IFN-β and activation of IRF-3. Furthermore, inflammatory cytokine production in response to the TLR4 ligand, but not to other TLR ligands, was severely impaired in TRIF-deficient macrophages. Mice deficient in both MyD88 and TRIF showed complete loss of nuclear factor kappa B activation in response to TLR4 stimulation. These findings demonstrate that TRIF is essential for TLR3- and TLR4-mediated signaling pathways facilitating mammalian antiviral host defense.
Interfacial Properties Between CVD Diamond and Titanium
Authors: Baek Sung Hyun , Mihec Damian F. , Metson James B.
Published: July 2003

The role of carbide and oxy-carbide films in the adhesion of diamond films on commercial pure Ti metal, and a Ti, 6%Al, 4%V substrates was examined. It was found that the carbon to oxygen ratio in an oxy-carbide structure formed at the interface broadly correlates with the adhesive strength of the diamond/substrate bond. Deposition experiments with substrates including titanium and its alloys, suggest the nature of the substrate is important in aiding carbide and subsequently, diamond formation. XPS depth profiling for Ti-6Al-4V indicates that the mode of TiC formation on pure Ti and Ti-6Al-4V is significantly different because of the segregation of aluminium. This contributes to a change of TiC stoichiometry and morphology. SIMS depth profiles also show that the interfacial surface on Ti-6Al-4V contains several percent of aluminium and nitrogen, both at the outermost surface and in the interior of the interfacial layer. The aluminium is enriched at the surface as compared with the bulk concentration.
A Simple Synthetic Route to MoS2 and WS2 Nanoparticles and Thin Films
Authors: Lee G. H. , Jeong J. W. , Huh S. H. , Kim S. H. , Choi B. J. , Kim Y. W.
Published: July 2003

We produced both MoS2 and WS2 nanoparticles by thermally decomposing M(CO)6 (M = Mo, W) in excess of H2S by using a hot filament. Both highly pure crystalline MoS2 and WS2 nanoparticles were efficiently produced over the filament temperature range from 300 to 800 °C. Particle diameter ranged from 2.0 to 5.0 nm and from 3.0 to 6.0 nm for MoS2 and WS2 nanoparticles, respectively. Fullerene-like particles such as nanotubes, onions, and empty and nested hollows were not produced. Both MoS2 and WS2 nanoparticles have a hexagonal close packed structure. Cell constants are determined to be a = 3.09 and c = 12.61 Å and a = 3.09 and c = 12.47 Å for MoS2 and WS2 nanoparticles, respectively, which are all consistent with the corresponding bulk values. Thin films of MoS2 and WS2 were also prepared by chemical vapor deposition of MoS2 and WS2 on stainless steel disks at 600-650 °C and low friction coefficients were obtained at an ambient atmosphere for both MoS2 and WS2 thin films, implying that they can serve as good solid lubricants.
Evaluation of Thin-Film Residual Stress Using Nano-Indentation Combined with an Atomic Force Microscope
Authors: Lee Yun Hee , Kwon Dongil , Jang Jae Il
Published: July 2003

Thin-film stress changes the shape of nanoindentation loading curve. The change in the indentation load is treated as the effect of the residual stress on the indenting deformation. A residual-stress-induced normal load is defined as a multiple of contact area and plastic deformation-sensitive deviator stress component extracted from the equi-biaxial thin-film stress. A final equation for the residual stress is derived from the residual-stress-induced normal load by considering an integration along a depth-controlled stress-relaxation route. This proposed model is applied to the analyses of the nanoindentation curves for diamond-like carbon thin films. The residual stresses from the nanoindentation analyses were consistent with the values obtained by the conventional curvature method.
Near-Net Ceramic Micro-Tubes Fabricated by Electrophoretic Deposition Process
Authors: Yoo Ju Hyun , Gao Wei
Published: July 2003

The forming or shaping of ceramic micro-tubes is usually difficult with conventional ceramic processing. In some cases, parts that are not possible to produce by any other techniques can be fabricated with electrophoretic deposition process (EPD). In this paper, EPD is shown to be an operationally simple, rapid, and reliable technique for forming a wide range of ceramic micro-tubes required in electronic devices such as actuators, motors, optical modulators and MEMS. These topics will be discussed in detail.
Interfacial Bonding Strength of Graded ZrO2/NiCrAlY Coatings Accumulated by Detonation Gun Spraying
Authors: Seo Do Won , Lim Jab Kyoo
Published: July 2003

Functionally graded ZrO2/NiCrAlY coatings are produced by detonation gun spraying using spheroid powers as the feedstock. A commercial Ni-based alloy is used for metallic substrate. The composition and microstructure are changed gradually through the six-layer graded coatings that are beneficial for the improvement of mechanical and thermal properties of the coatings. The shear test is carried out to analyze the interfacial bonding strengths of graded coatings. And non-graded duplex coatings are tested for comparative study. The effects of cross-sectional size and crosshead speed on interfacial strength properties are also studied. Results show that interfacial strengths of graded coatings are increased gradually with increase of volumetric rate of NiCrAlY. The bonding strength of the functionally graded coating is about twice as high as that of the duplex coating. For duplex coating without metallic interlayer and below 5 mm/min, the interfacial bonding strength of ZrO2/NiCrAlY interface increase with increasing crosshead speed.
Improvement of Oxidation-Resistance of TiAl Alloy by Electric Discharge Nicraly Coating
Authors: Iino Y. , Yaesawa K.
Published: July 2003

The effect of NiCrAlY and NiCrAiY-50%NiAl coating by electric discharge technique on oxidation of TiAl alloy at 800°C in air was studied. The mass gain of the non-coated specimen increased linearly with exposure time, while that of the coated specimen increased at first then saturated to a lower value. The coating was further carried out on notch root surface of notched compact tension specimen, which was low cycle-fatigued at 800°C in air. The coating had no deteriorative effect on low cycle fatigue crack initiation.
Polyaniline Coatings for Aluminium: Preliminary Study of Bond and Anti-Corrosion
Authors: Fujita Junko , Hyland Margaret M.
Published: July 2003

Coatings of the emeraldine base (EB) form of polyaniline were investigated as anti-corrosion coatings for aluminium. A very thin layer of polyaniline was deposited from solutions of 1-Methyl-2-Pyrrolidinone (NMP) onto 5005 Al alloy surfaces pretreated in various ways. X-ray Photoelectron Microscopy (XPS) was used to examine the nature of the interaction between the polyaniline coating and the aluminium surface oxide both prior to, and after exposure to moisture in a controlled humidity chamber. A chemical interaction between the polyaniline coating and the surface aluminium oxide takes place, as evidenced by changes in the ratio of reduced/oxidized N in the polyaniline and changes in the oxide/hydroxide ratio of the aluminium oxide, but this varies depending on pre-treatment of Al. On exposure to humidity, the aluminium oxide underneath coatings showed limited growth, while untreated surface oxide layer grew rapidly.
Diamond Growth on Haynes 214 Alloy
Authors: Mihec Damian F. , Baek Sung Hyun , Metson James B.
Published: July 2003

A major target in diamond deposition is the growth of heteroepitaxial diamond films that are free from impurities, grain boundaries and defects for use in electronic applications. Nickel has been identified as a material with a close lattice match to diamond that minimises defect formation in diamond films but as a substrate, nickels' higher thermal expansion coefficient with respect to diamond, and the interfacial formation of amorphous and graphitic carbon before nucleation of diamond, leads to a weakened diamond/metal bond. Haynes 214 alloy is a nickel-based alloy used in high-temperature environments. Regions within this alloy contain amounts of aluminium known to affect the ability of nickel to stabilise amolphous carbon and graphite. Areas rich in aluminium discourage the formation of sp2 carbon, creating a barrier to carbon diffusion and allowing diamond nucleation to occur on the metal surface. Diamond deposition on Haynes 214 alloy using combustion assisted chemical vapour deposition (CACVD) rapidly produced a well structured, polycrystalline diamond film that typically delaminated with sample cooling. The film exhibited areas that were transparent corresponding to areas on the substrate rich in aluminium and dark areas matching nickel rich areas of the substrate surface catalysing the formation of amorphous and graphitic carbon.
Effects of Nitrogen Gas Flow and Film Thickness on Electric Properties of TiN Thin Film Deposited at Room Temperature
Authors: Wu Jingbo , Murakami Ri Ichi , Kondo Masaharu
Published: July 2003

In this study, TiN thin film was deposited onto a glass substrate by the inclined opposite target type DC magnetron sputtering method with the good electric characteristics. The coating of TiN thin film was carried out onto substrate at the temperature of 303 K. The effects of nitrogen gas flow and film thickness on transparency, electric resistivity and electromagnetic wave shielding effectiveness of TiN thin films were discussed. The experimental results obtained were summarized as follows: (1) The TiN thin film deposited at the room temperature showed very low electric resistivity of 8.8×10-5Ω.cm. The TiN film showed the crystal structure when the depositing time was over 20 min. (2) When the film thickness of TiN was very thin, the TiN thin film was transparent for the visible light. The electric resistivity decreased with increasing the deposition time. (3) The electric resistivity and the transparency of TiN thin film depended greatly on the nitrogen gas flow.
Rapid Estimation of the Height-Height Correlation Functions from the Synchrotron X-Ray and AFM Study of very Thin SnO2/α-Al2O3(0001) FILM
Authors: Rue Gi Hong , Sug Joung Young , Lee Su Ho , Ha Sook Jeong , Lee Kyung Sook , Kim Jin Gyu , Yoo Dae Hwang , Hwang Yoon Hwae , Kim Hyung Kook
Published: July 2003

For the defective semiconductor SnO2 thin film epitaxially grown on sapphire, height-height correlation functions are evaluated from x-ray scattering and atomic force mi-croscopy(AFM) by a quick method. The small value [Formula: see text] implies that the interfaces are fairly well correlated. This is consistent with the well-defined oscillation in the longitudinal diffuse scattering intensity.
Annealing Effects on Transparent Conducting Properties of Amorphous ZnO-In2O3 Films
Authors: Fukushima Akihiko , Hayashi Yukako , Kondo Kumiko , Moriga Toshihiro , Murai Kei Ichiro , Nakabayashi Ichiro , Tominaga Kikuo
Published: July 2003

Structural and transparent conducting properties of amorphous Zn-In-O films deposited by simultaneous sputtering of ZnO and In 2 O 3 targets facing each other were reviewed. Post-annealing under the reductive gas flow was effective on improving unevenness of the amorphous films.
Electrochemical Properties of a Thiol Monolayers Coated Gold Electrode Modified with Osmium Gel Membrane as Enzyme Sensor
Authors: Yabutani Tomoki , Okada Nobuyuki , Maruyama Kenichi , Motonaka Junko
Published: July 2003

The electrochemical behavior of an enzyme sensor for glucose using a gold electrode modified with thiol self-assembled membrane and osmium complex gel as an electron transferring mediator has further been investigated by electrochemical analysis. The gold electrode was initially coated with aminomethanethiol self assembling mono layer membrane(thiol-SAM) and then immobilized with glucose oxidase using poly(vinylpyridine-co-allylamine) (PVP-co-AA), gel coordinated with osmium bipyridine complexes (GOD/Os-PVP-co-AA gel). The cleaning condition of the surface of the Au electrode prior to coating thiol SAM was optimized for reduction of interference caused by concomitant compounds. It was found that interfering influence was most efficiently reduced in the case of use of the Au electrode immersed into nitric acid. The current ratio with a thiol coated gold electrode modified with Os-PVP-co-AA gel in glucose solution in the presence to absence of ascorbic acid, acetaminophen, and uric acid ( I D+I / I I ) was 1.006, 1.014, and 1.018, respectively. The peak current response of glucose in the electrode modified with thiol SAM was dropped to 60 – 98% as compared with that without thiol SAM.
A Micro Total Reflective Extrinsic Fabry-Parot Interferometric Fiber Optic Pressure Sensor for Medical Application
Authors: Heo Jin Seok , Lee Jung Ju , Lim Jeong Ok
Published: July 2003

This paper presents the newly designed fiber optic pressure sensor using the TR-EFPI fiber optic sensor with a single mode fiber (SMF), and a micro fabricated diaphragm. The output signal of TR-EFPI fiber optic pressure sensor can be easily analyzed based on the spliced loss based model and large deflection theory. Then, we can design the optimal length between the thin film of diaphragm and the end of single mode fiber. From these analyses, the relation between the applied pressure and the output signal of TR-EFPI fiber optic sensor can be simulated. Based on these processes, we can design the TR-EFPI fiber optic pressure sensor measuring various conditions by changing the size of thin film. As the newly designed TR-EFPI fiber optic pressure sensor can be fabricated in small size and has good sensitivity, it can be applied to medical instrument like pressure sensor and force sensor for catheter and minimally invasive surgery robot for safer surgery.
Cycloaddition Reactions of Dienes on the SI(100)-2 × 1 Surface
Authors: Choi Cheol Ho , Gordon Mark S.
Published: July 2003

Quantum mechanical methods were adopted to study the surface reaction mechanisms of 1, 3-cyclohexadiene and acrylonitrile on the Si(100)-2x1 surface. According to the computed potential energy surfaces, both ⌊4+2⌋ and ⌊2+2⌋ cycloaddition products resulting from the reactions of surface dimers are possible due to the negligible activation barriers at the surface. Isomerization reactions among the surface products are very unlikely due to the predicted large activation barriers preventing thermal redistributions of the surface products. As a result, the distribution of the final surface products is kinetically controlled leading to a reinterpretation of recent experiments. An intermediate Lewis acid-base type complex appears in both the ⌊4+2⌋ and ⌊2+2⌋ cycloadditions of acrylonitrile entrance channels, indicating that the surface may act as an electrophile/Lewis acid towards a strong Lewis base substrate.
Design and Construction of Automated Amperometric Immunosensing System
Authors: Yasuzawa Mikito , Hamada Hiroyuki , Oga Keisuke , Fuchiwaki Yusuke
Published: July 2003

An automated amperometric immunosensors for the quantification of transferrin was fabricated using two monoclonal IgG class anti-rat transferrin antibodies, 15C2H3 and 22A06D2. The former was immobilized on a gold electrode, while the latter was conjugated with the positively charged polymers containing ferrocenyl groups. The quantitative analysis of transferrin was investigated by measuring the electrooxidation current of ferrocene, which is proportional to the transferrin concentration for the equivalently observed sandwich formation. The deposition of electroconductive polymers, polypyrrole (poly-P) and poly⌈ferrocenyl-methyl-3-(pyrrol-l-yl)propyldimethylammonium bromide⌉ (poly-FP), were performed on the surface of antibody-immobilized gold electrode in order to increase the efficiency of the electron transfer between the antibody-cojugated ferrocence and the gold electrode, and to eliminate the nonspecific binding of ferrocene-labeled antibody by a mutual repulsion.
Preparation of Glucose Sensor Using Polydimethylsiloxane / Polypyrrole Complex
Authors: Yasuzawa Mikito , Inoue Shigeru , Imai Shinji
Published: July 2003

New glucose oxidase (GOD) immobilized glucose sensors were prepared by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) on the platinum wire electrode precoated with the mixture solution of pyrrole derivative GHP, polydimethylsiloxane (PDS) and Nafion. The addition of Nafion into the precoating mixture solution was essential to obtain suitable sensor sensitivity. However, the sensitivity was about the half of that of the electrode without PDS precoating. Although, the introduction of Nafion was effective to improve the long-term stability of the enzyme-immobilized electrode, the electrode prepared using Nafion, PDS and GHP performed excellent long-term stability even at the measurement and storage temperatures of 40°C. Relatively constant response current was obtained over 30 days under the condition of 40°C and over 9 months measured at 25°C. Moreover, the GOD-immobilized GHP polymer film prepared on the electrode precoated with GHP, PDS and Nafion solution, was found to have excellent hemocompatibility from the result of platelet rich plasma contacting test.
C/SiC Multilayer Coating for the Oxidation Resistance of C-C Composite by Low Pressure Chemical Vapor Deposition
Authors: Kim J. I. , Kim W. J. , Choi D. J. , Park J. Y. , Ryu W. S.
Published: July 2003

Functionally graded materials (FGM) consisting of C and SiC were deposited between the carbon fiber reinforced carbon (C-C) composites and the SiC coating layer by low pressure chemical vapor deposition (LPCVD) method to reduce the thermal stress. The compositions of the graded layers could be easily controlled to various steps by manipulating the input ratio of CH 3 SiCl 3 to C 2 H 2. The residual stresses for the designed compositional distribution were calculated by finite element method (FEM). The designed FGM layers were coated experimentally on the C-C composites and the oxidation behavior of the composites was investigated.
A Study on the Deposition of ITO Films at Low Temperature by Inclination Opposite Target Type DC Magnetron Sputtering Method
Authors: Shin Do Hoon , Murakami Ri Ichi , Minamiguchi Jun , Kim Yun Hae
Published: July 2003

In the present study, the ITO films were produced onto plastic film substrate at room temperature by the inclination opposite target type DC magnetron sputtering equipment, in which a metallic indium tin alloy target was used. The effects of oxygen flow rate and bias voltage on the electric resistivity and transparency of the ITO films were discussed. For low electric resifitivity of the ITO films, the electromagnetic shielding effectiveness was studied. The results obtained were as follows: (1) The ITO films produced at room temperature has very smooth surface. (2) The electric resistivity of ITO films deposited at room temperature showed minimum value at the oxygen flow 0.4 sccm. (3) The electric resistivity of ITO films deposited at room temperature depended on the bias voltage and showed the minimum value in the bias voltage of -70V. (4) When the optimum coating conditions were selected, the electric resistivity of 3.l2 × l0-4Ω·cm was obtained. (5) When the bias voltage was -70V, the ITO films deposited at room temperature showed the most electromagnetic shielding effectiveness.
Electromagnetic Wave Shieding Effectiveness of Carbon Fiber Sheet Coated Ferrite Film by Microwave-Hydrothermal Process
Authors: Murakami Ri Ichi , Yamamoto Hidetoshi , Kim Chan Kong , Yim Cheol Mun , Kim Yun Hae
Published: July 2003

The developments of electromagnetic wave shielding materials are strongly required because the malfunction of electronic equipment, mobile phone and wireless LAN avoids. In this study, it was investigated that the electromagnetic shielding effectiveness of carbon fiber sheets were enhanced by the ferrite which was coated by the microwave hydrothermal process. For coated carbon fiber sheet, the effects of ferrite and lamination of carbon fiber textile on the electromagnetic wave shielding effectiveness were discussed. In the range of frequency (100 – 1 GHz), the electromagnetic wave shielding effectiveness was measured by using TEM-Cell. The electromagnetic wave shielding effectiveness was greater for the coated carbon fiber sheets than for the uncoated carbon fiber sheets. When the insulation film was located between two carbon fiber sheets, the electromagnetic wave shielding effectiveness increased.
Transparent Conducting ITO Films Reactively Sputtered on Polyethylene Terephtalate Substrates Without Heat Treatment
Authors: Kim Hyun Hoo , Lee Moo Young , Kim Kwang Tae , Yoon Sahng Hyun
Published: July 2003

Indium tin oxide (ITO) films have been deposited on PET and glass substrates by DC reactive magnetron sputtering without post-deposition thermal treatment. High quality films have been deposited by optimizing the sputtering parameters. The influence of the working gas pressure, DC power, and oxygen partial pressure has been investigated. The lowest resistivity of ITO films deposited on PET substrates was 6×10-4Ωcm. It has been obtained at a working pressure of 3 mTorr and DC power of 30 W. The sheet resistance and optical transmittance of these films were 22 Ω/square and 84%, respectively. The best values of figures of merit for the electrical and optical chardcteristics such as T / R sh and T 10/ R sh are approximately 38.1 and 7.95 (×10-3 Ω-1), respectively.
Analysis of Stress Singularity Induced in Viscoelastic Thin Layer Subjected to Shear Loading
Authors: Park Myung Kyu , Lee Sang Soon , Suh Chang Min
Published: July 2003

This paper deals with the stress singularity developed in a viscoelastic thin layer bonded between two rigid bodies and subjected to a shear loading. A boundary element method is employed to investigate the behavior of interface stresses. Within the context of a linear viscoelastic theory, a stress singularity exists at the point where the interface between one of the rigid adherends and the adhesive layer intersects the free surface. Numerical results are presented for a given viscoelastic model, indicating that such stress singularity might lead to edge crack or delamination.
Reliability Evaluation and Failure Analysis for NTC Thermistor
Authors: Jung Joon Sik , Kim Jin Woo , Kim Myung Soo , Jang Joong Soon , Ryu Dong Su
Published: July 2003

Failures of NTC thermistor are analyzed. Visual inspection, electrical parameter test, non-destructive test, and destructive physical analysis were performed on the field samples to identify the root cause of failure. It was found that the predominant failure mechanism was the copper migration of dumet (copper-clad alloy) at glass-PVC interface for glass-coated chip type NTC thermistor molded with PVC. Next, an accelerated life test is designed to predict the lifetime. Temperature, voltage, and humidity are considered as accelerating variables. Under the assumptions of a general life-stress relationship and Weibull lifetime distribution, the parameters of life-stress relationship and acceleration factor for the migration are estimated by analyzing the test data.
Copper Metalization Using Electroplating Process
Authors: Park Byung Nam , Choi Sie Young
Published: July 2003

Recently, electroplating method which deposits copper films by using cupric sulfate solution, has been proposed. The electroplating method has the advantages of simplicity, safety, low cost, low deposition temperature, high purity, low resistivity, and high capability of gap filling. In this method, an electrical contact is made to the seed layer and a current is passed such that the reaction ⌊ Cu 2++ 2e → Cu (0)⌋ occurs at the wafer surface (cathode). At the anode, an oxidation reaction occurs which balances the current flow at the cathode, thus maintaining electrical neutrality in the cupric sulfate solution. The seed layer used in this experiment was a copper thin film deposited using the sputtering method on p-type (100) silicon wafer using Ta thin film for barrier material. The thickness of seed and barrier layer were 400 and 600 Å respectively. The electroplating process was performed for 5min with a cathode current of 2A and a electrode distance of 4 cm. The intensity of magnetic field was about 200 – 400 Gauss. The pulse current generator was used for uniform surface and gap filling. The thickness and the sheet resistivity were measured using an α-step profiler and 4-point probe system, respectively. Scanning electron microscopy (SEM) was used to investigate the film morphology and the surface grdin size of the plated copper films. X-rdy diffraction(XRD) was performed for the crystal texture. The impurity levels and atomic composition were determined using Auger electron spectroscopy (AES).
Microstructure and Dielectric Properties of Tungsten Bronze Structured KLN and BNN Ceramics: TiO2 Effect
Authors: Wang Peng , Xu Shu Lun , Lee Joon Hyung , Kim Jeong Joo , Cho Sang Hee , Lee Hee Young
Published: July 2003

The effect of TiO2 addition on microstructure and dielectric characteristics of tungsten bronze structured K 6 Li 4 Nb 10 O 30 (KLN) and Ba 2 Na 1 Nb 5 O 15 (BNN) was examined. Solid solution limits of TiO2 in KLN and BNN are thought to be around 0.5 and 0.4 mol, respectively. As the amount of TiO2 increased, lattice constants of KLN and BNN decreased. Microstructure of BNN was sensitively influenced by TiO2 addition, which was explained by the generation of vacancies. TiO2 addition was effective in decreasing the phase transformation temperature of KLN, while it was effective in suppressing the dielectric curve of BNN at the phase transformation temperature.
Effect of Nb2O5 Content on Microstructure and Dielectric Properties of Ba2-2xNa1-xNb5O15-5x/2 Ceramics
Authors: Wang Peng , Lee Joon Hyung , Kim Jeong Joo , Cho Sang Hee , Lee Hee Young
Published: July 2003

The effect of Nb 2 O 5 content on the microstructure development and the dielectric characteristics of tungsten-bronze-structured polycrystalline Ba 2 Na 1 Nb 5 O 15 (BNN) ceramics was studied. The compositions of stoichiometry, Nb 2 O 5–deficient and Nb 2 O 5–excess BNN were prepared and sintered at 1250 °C for 2 h in oxygen. We report the development of second phases, microstructure and dielectric behavior of polycrystalline BNN ceramics, which was not reported ever. The Nb 2 O 5 content affect lattice constant of the sintered body, which contributed to the change of phase transformation temperature. The stoichiometric BNN showed the lowest densification, while an optically transparent sample was obtained in Nb 2 O 5–excess highly dense sample.