bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Modified Solution Heat Treatment on δ- Phase and Low Cycle Fatigue Properties of Inconel 718 Alloy
Authors: Hong Jae Keun , Park Ji Hong , Park Nho Kwang , Kim Seong Jun , Kang Chung Yun
Published: March 2009

Effects of solution treatment on the microstructure and mechanical properties in wrought
Alloy 718 were investigated. For the improvement of tensile and fatigue properties of wrought
Alloy 718, a modified solution heat treatment(MSHT), heating at 1000 for 3 minutes followed by
furnace cooling at the rate of 3/minute and holding at 985 for 8 minutes, was proposed. This
treatment was performed repeatedly 3 times and the samples were subject to the standard aging
treatment. For the purpose of comparison, a standard heat treatment(SHT) was also performed. The
microstructures of modified solution heat treated specimens showed that small spherical shaped δ-
phases were precipitated without grain growth, and the amount of δ-phases was smaller than that of
standard heat treated specimens. However, the δ-phases of the standard heat-treated specimen
showed needle-like morphologies. Tensile and low cycle fatigue tests were performed on both
modified heat-treated and standard heat-treated specimens at room temperature, 350 and 650.
Low cycle fatigue tests on the modified heat treated specimens showed promising results without
reduction of strength. However, the tensile properties of modified solution treated specimens was
almost the same as those of standard heat treated materials both at room temperature and 650.
Vacuum Carburizing of AISI S7 Tool Steel
Authors: Chiu Liu Ho , Chen Yu Jen , Wu Chang Hui , Chang Heng
Published: March 2009

The effects of vacuum carburizing under an acetylene atmosphere at 950 and 1000,
followed by gas quenching and tempering at various temperatures on the properties of AISI S7
shock-resistant tool steel were studied. As carburized specimens undergo low temperature
tempering, the surface hardness of the quenched specimens carburized at 1000 is lower than those
of the specimens carburized at 950, due to the large amount of retained austenite in specimens
carburized at 1000. Under high temperature tempering, specimens carburized at 1000 have
higher surface hardness than specimens carburized at 950. As specimens are tempered in the
range between 450 to 550, the surface hardness of carburized specimens show a modest
increase due to the secondary hardening effects. According to the fracture toughness data, the
toughness of carburized specimens peaked at tempering at 600.
Influence of Atmospheric-Pressure Plasma Treatment on Surface of Polyimide Film
Authors: Park Soo Jin , Lee Eun Jung , Kwon Soo Han
Published: March 2009

In this work, the effects of atmospheric-pressure plasma treatment of polyimide films on
surface and dielectric characteristics were studied by using X-ray photoelectron spectroscopy (XPS),
surface free energies, and dielectric spectrometer. The total surface free energies and dielectric
constants of plasma treated polyimide film were deareased with increasing the treatment time, which
was mainly due to a lower London-dispersive component, while the specific component was
increased. This could be attributed to an increase of the polar fluorine groups of polyimide per unit
surface area. And the fluorine content of the polyimide film was increased with increasing the amount
of the treatment time, resulting in decreasing dielectric constant of the film. It was found that the
replacement of fluorine led to the decrease of the local electronic polarizability of polyimide, or to the
increase of the free volume, which could be attributed to the relatively large volume of fluorine.
Preparation and Characterization of Soft Phase Magnetic α-Fe Nanoparticles by Different Methods
Authors: Cha Hyun Gil , Kim Young Hwan , Lee Don Keun , Jeong In Chul , Kwon Hae Woong , Kang Young Soo
Published: March 2009

The magnetic α-Fe nanoparticles were carried out using two-preparation methods that
include solution phase metal salt reduction and organometallic precursor decomposition. Under the
different reaction conditions such as precursor and reaction time, the magnetic properties of α-Fe
nanoparticles were studied. The size of nanoparticle was confirmed by transmission electron
microscope (TEM) images. The magnetic properties were characterized with saturation
magnetization(Ms) from hysteresis loop by vibrating sample magnetometer (VSM). The crystallinity
and structure of α-Fe nanoparticles was investigated by X-ray diffraction (XRD).
Baeyer-Villiger Reaction of Adamantanone over Sn-Containing Hydrotalcite-Like Catalysts
Authors: Yang Zhi Qiang , Park Sang Eon
Published: March 2009

Sn-containing hydrotalcite-like compounds were prepared by three different methods such as (i) direct synthesis, (ii) ion-exchange and (iii) grafting. These catalysts were proved to have framework Sn species by powder X-ray diffraction (XRD) analysis and UV-vis spectroscopy. The catalysts prepared by three methods were found to be active and selective for the liquid phase Baeyer–Villiger (BV) oxidation of admantonone using hydrogen peroxide (H2O2) as an oxidant and acetonitrile as a solvent. The Sn-hydrotalcite-like catalysts prepared by ion-exchange method exhibited better catalytic performance than the catalysts prepared by other two methods. Among the ion-exchanged hydrotalacite-like catalysts, 3% Sn ion-exchanged hydrotalcite exhibited superior activity at 30% conversion and 100% selectivity.
Microwave Synthesis and Characterization of Stacked AlTS-1
Authors: Choi Kwang Min , Burri David Raju , Han Sang Cheol , Park Sang Eon
Published: March 2009

Nano-stacked aluminum titanium silicalite-1(NS-AlTS-1) zeolite with MFI structure was prepared by direct synthesis using a microwave technique and also prepared the conventional aluminum titanium silicalite-1(AlTS-1) by conventional hydrothermal method for comparison. The morphological aspects of these materials were investigated with the help of SEM. The zeolite framework Al location was confirmed by 27Al MAS NMR. The existence of Ti species in the zeolite framework and its co-ordination environment was investigated by UV-Vis spectroscopy. The uni-model distribution of weak acidic sites was estimated by the well established NH3-TPD technique.
The Mechanical Milling Behavior of Ductile Cu Flakes when Using Ultrafine Al2O3 Reinforcements
Authors: Lee Min Ku , Kim G.H. , Hong Sung Mo , Lee Jong Keuk , Hong Sung Jei , Uhm Young Rang , Rhee Chang Kyu
Published: March 2009

In this study the effects of harder ultrafine Al2O3 particles on the mechanical milling of
ductile Cu flakes (200mesh, 70μm) have been investigated. The small hard Al2O3 particle in the
mixture acted as an effective milling agent not only by inducing a drastic change of the Cu
morphology from flattened flakes to equiaxed crystals but also by reducing the milling time
required for a uniform dispersion of Al2O3 in the Cu matrix. This was more pronounced as the
Al2O3 concentration increased. A critical concentration of the reinforcing Al2O3 required for a shape
change was observed at the range of 8 to 9wt. %. All the hard Al2O3 particles were uniformly
embedded in the ductile Cu matrix regardless of the concentration of Al2O3. By increasing the
milling time, the weldment and fragmentation of the Cu flakes became significant and a uniformly
distributed equiaxed composite structure (13wt.% Al2O3) was obtained at above 70 min..
Preparation of Impurity-Doped TiO2 Nanoparticles and Their Applications for Photocatalysis and Biopanning
Authors: Kim Yong Tae , Im Sang Kyun , Shim Yong Bo , Myung Hee Joon , Lee Wan In , Chae Hee K.
Published: March 2009

A series of surface-modified TiO2 nanoparticles were prepared and their
photocatalytic effects were evaluated by degradation of Acid red dye in aqueous
solution under UV light irradiation. Phage display peptide libraries were used for
peptide sequence to bind the doped TiO2 particles selectively.
Preparation and Characterization of Environmental-Friendly Epoxy Resins/Clay Nanocomposites
Authors: Jin Fan Long , Han Mi Jeong , Lee Jae Rock , Park Soo Jin
Published: March 2009

The environmental-compatible epoxy resins/clay nanocomposites were prepared by using epoxidized castor oil (ECO) and two ion-exchanged clays. The glass transition temperature (Tg) and mechanical interfacial properties of ECO/clay nanocomposites were investigated. As a result, the nanocomposites showed higher Tg than that of neat ECO. The mechanical interfacial properties of both the nanocomposites were significantly increased on increasing the clay content.
Graft Polymerization of Styrene onto Alumina Nanoparticles by a Radiation
Authors: Jung Chan Hee , Choi Jae Hak , Lim Youn Mook , Jeun Joon Pyo , La Hyun Shil , Kang Phil Hyun , Nho Young Chang
Published: March 2009

Polystyrene-grafted γ-Al2O3 nanoparticles were successfully synthesized by a high
energy irradiation technique. Surface modification of the nanoparticles with silane coupling agents
was performed to introduce active sites on the γ-Al2O3 nanoparticles for a radiation-induced graft
polymerization. The polymer graft yield increased with the absorbed dose. The graft yield was
higher at a 50 vol% monomer solution than at 70 vol%.
Microwave Synthesis and Catalytic Applications of Novel Cobalt Incorporated Nickel Phosphate
Authors: Shaikh Isak Rajjak , Park Sang Eon
Published: March 2009

The novel cobalt incorporated nickel phosphate, (CoNiPO4), has been synthesized from
aqueous system with triethyl amine (TEA) as an organic template using the microwave assisted
reaction system under weak basic conditions. Among various factors used for synthesis, the pH of
the reactant mixture and homogeneous heating under microwave could be the decisive factor to
form the cobalt incorporated microporous VSB-n type nickel phosphate with novel structural
parameters and unique stacked sheet like morphology. Its ability to perform as heterogeneous
catalyst was discovered in the aerial oxidation of ethylbenzene and liquid phase oxidation of styrene
using aq. hydrogen peroxide as an oxidizing agent.
Preparation and Characterization of Pt Counter Electrode with Buffer Layer for Dye-Sensitized Solar Cell
Authors: Kim Hyun Ju , Lee Dong Yoon , Koo Bo Kun , Lee Won Jae , Song Jae Sung
Published: March 2009

Dye-sensitized solar cell (DSSC) is of great interest as one of renewable
energy sources. So far, many investigations related to TiO2 electrode, dye, electrolyte,
Pt counter electrode, etc. were carried out. Here, we focus on Pt counter electrode for
providing an enhanced catalytic property and physical stability. Pt has high-conductivity
and superior catalytic properties. However, in case of Pt as counter electrode for DSSC,
there exists partial problem due to poor adhesion between Pt and FTO glass. In this
work, we tried to enhance the properties of Pt catalyst by two methods; first, the
insertion of buffer layer under Pt thin film; second, the heat treatment of Pt films. We
report the effect of buffer layer using Cr and Ti and the effect of heat treatment on Pt
electrode under 400oC. Electrochemical characteristics of Pt electrodes were measured
using electrochemical impedance spectroscopy and cyclic-voltammetry. A degree of
electrode reaction, current density, electrode potential and interface resistance, etc were
discussed with measured electrochemical data. In comparison with sputtered Pt counter
electrode with and without buffer layers, heat-treated Pt counter electrode showed good
performance in terms of the current density and interface resistance properties.
Mesoporous Nitrides through Nano-Hard Templating Techniques
Authors: Vinu Ajayan , Anandan Srinivasan , Gokularkrishnan Narasimhan , Srinivasu Pavuluri , Mori Toshiyuki , Ariga Katsuhiko
Published: March 2009

Mesoporous carbon nitride materials have been synthesized using SBA-15 by
pore filling technique whereas mesoporous boron nitride and boron carbon nitride have
been prepared by elemental substitution technique using mesoporous carbon as template.
The obtained materials have been unambiguously characterized by sophisticated
techniques such as XRD, HRTEM, EELS, XPS, FT-IR and N2 adsorption. The
textural parameters of the materials are quite higher as compared to the respective
nonporous nitrides. These materials could offer great potential for the applications, such
as catalytic supports, gas storage, biomolecule adsorption and drug delivery.
Preparation and Cu(II) Complexation Characteristics of Carboxymethylated Polyethyleneimine (CM-PEI) / Microporous Activated Carbon Composite
Authors: Jung Y. , Yeon Jei Won , Ha Yeong Keong
Published: March 2009

We present the preparation and Cu(II) adsorption characteristics of a new and innovative composite which was composed of a carboxymethylated polyethyleneimine (CM-PEI) and an activated carbon with a nanopore less than 2 nm in diameter. In this study, we examined the adsorption phenomena of Cu(II) on the CM-PEI/F400 composite and evaluated the adsorption data using three kinds of isotherm models (Langmuir, Freundlich, and Temkin isotherms). It was found that the adsorption of Cu(II) on the CM-PEI/F400 composite obeys the Langmuir isotherm model. Furthermore, The Cu element mapping results showed that Cu was well distributed throughout all the surface of the composite particle, suggesting that the surface of the F400 particle was uniformly covered with CM-PEI.
Effect of Solvents on the Dispersion Stability of Alloy 625 Nanoparticles
Authors: Lee Eun Hee , Lee Min Ku , Rhee Chang Kyu
Published: March 2009

In order to select the most suitable solvent for the stable dispersion of Alloy 625
nanoparticles, we investigated the effects of several organic solvents on the dispersion stability.
After preparing suspensions with a dispersant, we characterized the dispersion stability of the
suspensions by means of visual inspection and Turbiscan transmission profiles. The dispersion
stability of the solvents increased in the following order: ethyl acetate, xylene, toluene, 2-propanol,
and ethanol. The polarity of the solvent affected the dispersion stability. The Alloy 625
nanoparticles were optimally dispersed in ethanol with the dispersant, Hypermer KD-2, which was
stabilized by the steric effect of the dispersant.
Five Strip-Type Dye Sensitized Solar Cells with Metal Grid Lines
Authors: Lee Won Jae , Ramasamy Easwaramoorthi , Lee Dong Yoon , Song Jae Sung
Published: March 2009

Dye sensitized solar cells (DSSC) have great potential alternative to
expensive conventional solar cells, since high efficiency and relatively simple
fabrication process. However, in large size cell, there is a key factor that delayed the
entry of such cells in commercial market. Performance of large size cell is lower than
small size cells, since a carrier loss occurs in high resistive TCO glass substrate. Here
we demonstrate a simple method to reduce resistive loss and efficient collection of
photo generated carriers via strip type cells with metal grids. Using strip type cells, we
constitute series and parallel type DSSC panels in order to achieve required voltage and
current respectively. Stripe cells were prepared from commercial TiO2 powder by screen
printing method. In addition, metal grids were established adjacent to sealant line. Using
these as unit cell, portable DSSC panels were assembled and I-V performance was
carried out in indoor light condition (fluorescent light, 30mW/cm2) and standard
condition (Pin 100 mW/cm2, AM 1.5).
The Fabrication of Iron Sulfide Powders for Enhancing the Machinability and the Comparison of Machining Behavior at the Sintered Steel
Authors: Ahn In Shup , Bae Sung Yeal , Kim Chul Jin , Jung Kwang Chul , Park Dong Kyu
Published: March 2009

Metal sulfide (MeS) is well known and widely used an additive for enhancing machinability, but the problems is extremely sensitive to reaction with moisture and thermal decomposition during sintering. In this study, micron or nano size compound powders of FeS were produced by mechano-chemical process. The machinability was also evaluated at the metal sulfide added sintered steel. Compared with the MnS additive, addition of the FeS powders to the iron resulted the formation of the sintering materials containing a spherical shape of pore, partly remained FeS rich-phase in iron matrix. Relative machinability behavior of sintering materials was investigated by the lathe manufacturing. Mechanical properties of sintering material with 1.2%FeS powders were improved rather than its using MnS powders.
Effects of Certain Variables on the Materials Properties of Nickel Electrodeposits: Current Density and Duty Cycle
Authors: Kim Dong Jin , Kim Hong Pyo , Kim Joung Soo , Urm Kee Won , Lee Sun Ho
Published: March 2009

Alloy 600 tubing can be repaired by using a Ni electroplating to have an excellent SCC resistance. In order to carry out a successful Ni electrodeposition inside a steam generator tubing, the effects of various parameters on the material properties of the electrodeposit should be elucidated. Hence this work deals with the effects of the applied current density and the duty cycle(Ton / (Ton + Toff)) of the pulse current on the material properties of the Ni electrodeposit obtained from a Ni sulphamate bath by analyzing the current efficiency, the potentiodynamic curve, the hardness and the stress-strain curve. Hardness, YS(yield strength) and TS(tensile strength) decreased whereas the elongation increased as the applied current density increased. This was due to a concentration depletion of the nickel ion at the interface of the electrodeposit/solution, and a fractional decrease of the hydrogen reduction reaction. As the duty cycle increased, the hardness, YS and TS decreased while the elongation increased. During an off time at a high duty cycle, the concentration depletion of the nickel ion could not be sufficiently recovered and the fraction of the hydrogen evolution reaction which is kinetically faster than the nickel ion reduction decreased, which contributed to a coarse grain sized electrodeposit. The experimental results of the hardness and the stress-strain curves were supplemented by the results of the potentiodynamic curve.
Development of an Integrity Evaluation System for Steam Generator Tubes in a Nuclear Power Plant
Authors: Kim J.C. , Lee Sang Min , Chang Yoon Suk , Choi Jae Boong , Kim Young Jin , Choi Young Hwan
Published: March 2009

Steam generators working in nuclear power plants convert water into steam from heat produced in the reactor core and each of them contains from 3,000 to 16,000 tubes. Since these tubes constitute one of primary barriers under radioactive and high pressure condition, the integrity should be maintained carefully during the operation. The objective of this research is to introduce an integrity evaluation system for steam generator tubes as a substitute of well-trained engineers or experts. For this purpose, a couplet examination has been carried out on the complicated evaluation procedure and an efficient system named as STiES was developed employing three representative integrity evaluation methods: fracture mechanics analysis (crack driving force diagram and J-integral/Tearing modulus method) and limit load method. Exemplary analyses for steam generator tubes with various types of flaws showed good applicability of the proposed integrity evaluation system. So, it is anticipated that the system can be used for the calculation of reference pressure to decide either the continued operation or repair until next outage.
Wear Characteristics of Tube-Support Components for a Nuclear Steam Generator under Fretting Conditions
Authors: Jeong Sung Hoon , Lee Young Ze
Published: March 2009

Tubes in nuclear steam generators are held up by supports because the tubes are long and slender. Fluid flows of high-pressure and high-temperature flows in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration) which cause fretting wear in contact part of tube-support. The reduction of tube thickness due to fretting wear of tube-support can threaten the safety of nuclear power plant. Therefore, a research on the fretting wear characteristics of tube-support is required. This work is focused on investigations of fretting wear characteristics and wear mechanisms of tube-support. Results show that the wear rate of tube is proportional to that of support and that with increasing the water temperature the wear volume of tube-support decreases because the oxidation rate decreases due to reduction of the oxygen concentration in contact surfaces. Also, the wear mechanisms of tube-support are abrasive and oxidational wear.
Analysis of Burst Pressure of Damaged Tubes Using Plastic Instability Analysis
Authors: Shin Kyu In , Park Jai Hak
Published: March 2009

Generally rupture of steam generator tubes occurs accompanying significant plastic
deformation. In this study, the burst pressure of a damaged steam generator tube is calculated from
the plastic instability analysis using the finite element method. Two wear types, flat and
circumferential types are considered. An equation for the burst pressure is proposed by using the
concept of strength reduction factor and the Svensson equation. The analysis results are also
compared with the experiment data from published references and they show a good agreement with
the experiment data.
The Application of Risk-Informed-Inservice Inspection to Recirculation Piping Welds of a Nuclear Power Plant
Authors: Hsieh K.C. , Ting Kung , Chen Kuen Tsan , Wu W.F. , Lu Y.L.
Published: March 2009

The implementations of RI-ISI can improve the substantial cost reductions as well as
dose reduction. From the points of the safety concern, the achievements of these procedures can
identify the inspection rank to promote the integrity of the present inspection program. Thus, this
paper presents the applications of RI-ISI to recirculation piping welds sensitized to IGSCC of
Taiwan BWR-4 nuclear power plant. The establishment of the risk evaluation can be referenced for
the regulatory and plant maintenance.
Multilayered and Arrayed Flexible Tactile Sensor Using PVDF
Authors: Choi Byung June , Jung Kwang Mok , Nam Jae Do , Lee Sang Moo , Yokokohji Yasu Yoshi , Choi Hyouk Ryeol
Published: March 2009

In this paper, we present a multilayered and arrayed flexible sensor made of Polyvinylidene Fluoride (PVDF), which can detect contact normal forces as well as positions. Since the sensor is flexible enough to be adapted to arbitrarily curved three-dimensional surfaces, it can be employed as the fingertip sensor of the robot hand, contact sensors for robot manipulators etc. The sensor displays enhanced characteristic features in terms of ease of fabrication, high spatial resolution and cost-effectiveness. We propose a new design of the sensor that can be fabricated without adopting sophisticated processing technique as well as with improved spatial resolution. In addition, an electronic hardware for signal processing using a DSP chip has been proposed and, its effectiveness is validated experimentally.
Development of Web-Based Fatigue Life Evaluation System for Reactor Pressure Vessel
Authors: Kim J.C. , Choi Jae Boong , Chang Yoon Suk , Kim Young Jin , Park Youn Won , Choi Young Hwan
Published: March 2009

While the demand on electric power is consistently increasing, public concerns and
regulations for the construction of new nuclear power plants are getting restrict, and also operating
nuclear power plants are gradually ageing. For this reason, the interest on lifetime extension for
operating nuclear power plants by applying lifetime management system is increasing. The 40-year
design life concept was originally introduced on the basis of economic and safety considerations. In
other words, it was not determined by technological evaluations. Also, the transient design data
which were applied for fatigue damage evaluation were overly conservative in comparison with
actual transient data. Therefore, the accumulation of fatigue damage may result in a big difference
between the actual data and the design data. The lifetime of nuclear power plants is mostly dependent
on the fatigue life of a reactor pressure vessel, and thus, the exact evaluation of fatigue life on a
reactor pressure vessel is a crucial factor in determining the extension of operating life. The purpose
of this paper is to introduce a real-time fatigue monitoring system for an operating reactor pressure
vessel which can be used for the lifetime extension. In order to satisfy the objectives, a web-based
transient acquisition system was developed, thereby, real-time thermal-hydraulic data were reserved
for 18 operating reactor pressure vessels. A series of finite element analyses was carried out to obtain
the stress data due to actual transient. The fatigue life evaluation has been performed based on the
stress analysis results and, finally, a web-based fatigue life evaluation system was introduced by
combining analysis results and on-line monitoring system. Comparison of the stress analysis results
between operating transients and design transients showed a considerable amount of benefits in terms
of fatigue life. Therefore, it is anticipated that the developed web-based system can be utilized as an
efficient tool for fatigue life estimation of reactor pressure vessel.
The Role of Simulations in Nanoscience, a Case Study: Gold Nanowires
Authors: Silva Edison Z. da
Published: March 2009

Suspended gold nanowires can be made atomically thin with as many as five atoms,
showing extremely large Au-Au bond distances. Using tools derived from Density Functional
Theory (DFT) we study many questions posed by the experiments. First we use realistic molecular
dynamics simulation to study the mechanisms of formation, evolution and breaking of these
atomically thin Au nanowires under stress. We show how defects induce the formation one-atom
chains that can grow as long as five-atoms before breaking. Results are in excellent agreement with
experiments, except for the resulting shorter bond distances. In order to address this question, we
use ab initio electronic structure calculations to show that the exceedingly large Au-Au interatomic
distances experimentally obtained could be the effect of impurities. We studied the effect of single
impurities H, B, C, N, O, S and small molecules as H2 on the nanowire's electronic and structural
properties, in particular how they affect the maximum Au-Au bond length.
Studies of Energy and Mechanical Properties of Single-Walled Carbon Nanotubes via Higher Order Cauchy Born Rule
Authors: Wang J.B. , Guo X. , Zhang Hong Wu
Published: March 2009

Based on the higher order Cauchy-Born rule, a nanoscale finite deformation continuum
theory, which links interatomic potentials and atomic microstructure of carbon nanotubes to a
constitutive model, is presented for analysis of the mechanics of carbon nanotubes. By using of
Tersoff-Brenner potential with two sets of parameters, the energy and Young’s modulus of graphite
sheet and single-walled carbon nanotubes are studied based on the theory presented. The findings
are in good agreement with the existing experimental and theoretical results.
Ab Initio Simulations of the Nucleation of Single-Walled Carbon Nanotubes
Authors: Li L. , Reich S. , Robertson J.
Published: March 2009

We investigated the nucleation of SWNTs and the role of metallic catalyst using firstprinciples
calculations. To avoid dangling bonds a closed cap forms on a metal surface. 6 pentagonal
rings are introduced into the cap, which reduces the strain energy. A unique tube chirality then grows
from the cap, which is controlled by the metal lattice at the nucleation stage. We found that chirality
of nanotubes affects the bond energies, including dangling bonds, carbon-carbon bonds & carbonmetal
bonds.
Inhomogeneous Lattice Distortion in Metallic Nanoparticles
Authors: Hu Wang Yu , Xiao Shi Fang , Yang Jian Yu , Qi Wei Hong
Published: March 2009

In the present paper, the size and temperature effects on lattice distortion of
Ag and Pt nanoparticles have been investigated in terms of atomic mean bond length
using the molecular dynamics simulations and the modified analytic embedded atom
method. It is found that the lattice contraction ratio decreases linearly with the
reciprocal of the particle size. The average value of lattice contraction over the whole
system is larger than that of the experimental data, and the average value of lattice
contraction in the inner core has a better agreement with the experiment results. This
phenomenon is mainly resulted by inhomogeneous lattice distortion. The surface
distortion and the size effect on the inner core distortion are remarkable. As the grain
size increases to a certain degree, the inhomogeneous surface lattice distortion is
mainly localized to the outer shell with a thickness of 2-3 lattice parameters.
Evolution Mechanisms of Nano-Clusters in a Large-Scale System of 106 Liquid Metal Atoms During Rapid Cooling Processes
Authors: Liu Rang Su , Tian Z.A. , Yi X.H. , Liu H.R. , Peng P.
Published: March 2009

A molecular dynamics simulation study has been performed for a large-sized system
consisting of 106 liquid metal Al atoms to investigate the evolution characteristics of nano-clusters
formed during rapid solidification processes. The cluster-type index method (CTIM) has been
applied to describe the structural configurations of the basic clusters and nano-clusters. The results
show that the icosahedral clusters (12 0 12 0) and their combinations play a critical role in the
microstructural transitions. The nano-clusters are mainly formed by combining basic and medium
sized clusters through continuous evolution. Their structural configurations are different from the
multi-shell structures obtained by gaseous deposition, ionic spray, and so on. The central atoms of
basic clusters composing the nano-cluster are bonded with each other, some central atoms are
multi-bonded, and others single-bonded.
Molecular Dynamics Simulation of the Solidification of Liquid Nickel Nanowires
Authors: Zhong Guo Rong , Gao Qiu Ming
Published: March 2009

Molecular dynamics simulation of the solidification behavior of liquid nickel nanowires
has been carried out based on the embedded atom potential with different cooling rates. The
nanowires constructed with a face-centered cubic structure and a one-dimensional (1D) periodical
boundary condition along the wire axis direction. It is found that the final structure of Ni nanowires
strongly depend on the cooling rates during solidification from liquid. With decreasing cooling rates
the final structure of the nanowires varies from amorphous to crystalline via helical multi-shelled
structure.
Size Effect on the Bandgap of Semiconductor Nanocrystals
Authors: Yang C.C. , Jiang Qing
Published: March 2009

The size-dependent valence-conduction bandgap of semiconductor nanocrystals are
predicted based on a model for size-dependent cohesive energy, without any adjustable parameter.
The model predicts an increase of the bandgap of semiconductors with decreasing crystalline sizes. It
is found that the model predictions are in good agreement with the available experimental results for
Si, ZnS, ZnSe, CdS, and CdSe nanocrystals.
Electronic States in a Non-Concentric Circular Quantum Corral
Authors: Ming Y. , Ding Z.J.
Published: March 2009

The eigenvalue problem in a non-concentric circular quantum corral was studied with a
conformal mapping method. The energy spectra of electrons show the properties of anti-crossing
between the nearby energy levels. This property of energy spectra is caused by the Jacobian of the
conformal transformation. We also give the probability density of the electronic states that confined
in the non-concentric circular quantum corral. Quantum corral geometry has a stronger effect on
electronic states of higher energies than that of lower energies.
Ab Initio Study of Hydrogen Desorption from Hydrogenated Diamond (100) Surface
Authors: Liu Feng Bin , Wang Jia Dao , Chen Da Rong , Liu Bing
Published: March 2009

By means of the density functional theory on the basis of generalized gradient
approximation, the reaction paths of the dehydrogenation from the diamond (100) surface was
deduced due to the reaction heat. Moreover, the most stable structure of the hydride diamond (100)
surface was obtained. The results indicate that the dehydrogenation is easier to take place at the same
C-C dimer and forms the parallel geometries. The parallel 1×1:1.5H, 2×1:H and parallel 2×1:0.5H
are the intermediate products during the hydrogen desorption process, while, 2×1:H is the most
stable structure of the hydride diamond (100) surfaces. The calculated reaction heat is in accordance
with the experimental results.
Contribution of Porous Pad to Chemical Mechanical Polishing
Authors: Zhang Chao Hui , Luo Jian Bin
Published: March 2009

Chemical mechanical polishing (CMP) is a widely used technique to achieve high level of
global and local planarity required in integrate circuit (IC) areas, which pleas for concentrate
researches. A preliminary wafer-scale flow model for CMP is presented considering the roughness
as well as the porosity and compressibility of the pad. Pressure distributions for three kinds of pad
roughness: cosine shape, two-scale cosine shape and actual roughness were given with the help of
numerical simulation by solving the corresponding two-dimensional slurry flow model. Pressure
fluctuations and peaks can be seen from the results. The model predictions will be conducive to the
removal rate and mass transport computation. The research is a qualitative one and will pave the
way for further explorations of mechanisms of CMP process.
Molecular Dynamics Simulation for Compressive Mechanics Properties of SWCNT with Random Distributed Vacancies
Authors: Cheng Qin , Wang Xiu Xi , Ni Xian Gui
Published: March 2009

Configurations of single-walled carbon nanotubes (SWCNTs) with randomly distributed
vacancies were generated by numerical method. Molecular dynamics (MD) method was used to
investigate the compressive mechanics properties of SWCNTs with vacancies. The simulation results
show that the SWCNTs with vacancies have more complicated deformation procedures and the
Young’s modulus is lower than the corresponding perfect SWCNTs. The Young’s modulus of the
SWCNTs with no more than 20 vacancies ranges from 940Gpa to 620Gpa, and its value is
approximately linearly proportional to the number of vacancies. It is found that local buckling first
appears in the surface region having high density of vacancies of (10, 10) SWCNTs under axial
compression. As the loading increases, SWCNTs with more vacancies have more complicated
buckling configuration and sluggish energy variation. Under a case of the same displacement load the
more vacancies the SWCNT has, the more complicated the mechanical behavior is. SWCNTs with 20
vacancies can still maintain self structure stabilization, this validates that SWCNTs have good spacial
stabilization.
Simulation of 3D Layer-By-Layer Photonic Crystals
Authors: Fan S.S. , Guo R. , Li Z.Y. , Huang W.H.
Published: March 2009

3D layer-by-layer photonic crystals possess a full photonic band gap.
Simulation of 3D layer-by-layer photonic crystals can optimize the parameters of the
photonic crystals to get useful photonic band gap by solving Maxwell’s equations
using the plane-wave-based transfer-matrix method. The relations between the
parameters (rod pitch a, rod width w, rod thickness h and rod refractive index n) and
the photonic band gap have been simulated. We also have fabricated a 3D
layer-by-layer photonic crystal with femtosecond laser microfabrication technique
through two-photon-absorption photopolymerization of resin. Its reflection spectra
have been detected which agree with the simulation result.
Electrochemical Double-Layer Capacitors Based on Activated Bamboo-Shaped Carbon Nanotubes
Authors: Tao X.Y. , Zhang X.B. , Zhu W.M. , Wang Y.W. , Liu F. , Tu J.P. , Zhang L. , Cao S.S. , Min C.Y.
Published: March 2009

Bamboo-shaped carbon nanotubes (BCNTs) have been synthesized by chemical vapor
deposition method. The activated BCNTs after simple ball milling and KOH etching are used as
polarizable electrodes in electric double layer capacitor (EDLC). Our results show that the specific
capacity of BCNTs can be improved by the activation treatment.
Large Area, Nanoparticulate Metal Oxide Coatings for Consumer Nanotechnologies
Authors: Steiger Rolf , Beer Robert , Fernandez-Sanchez J.F. , Spichiger-Keller U.E.
Published: March 2009

Large area coatings containing nanoparticulate metal oxides dispersed in polymers are
manufactured at high speed (up to 200 m2 /min.) by curtain- or cascade coating on flexible substrates
near room temperature. Simultaneously coated multilayers, which may contain different metal oxides,
show interesting new properties for industrial applications. Thick (40 $m) coatings with rare-earth
doped aluminum oxide nanoparticles have been commercialized for waterfast ink-jet media which
are dry to touch after printing, show photo-parity and are very stable towards water, light and
environment if appropriate inks are used. Strong capillary forces due to nanoporosity allow instant
ink-absorption. Experimental techniques used to develop these materials and results related to
imaging parameters are discussed. Thin layers (1-10 $m) of nanoparticulate, nanoporous TiO2 and
LiMn2O4, dispersed in non-electroactive polymers such as polyethylene glycols, can be used as
electrodes for rechargeable Li-ion batteries with very fast charge-discharge cycles and high power
performance. The excellent ion-conducting properties of unsintered, nanoparticulate coatings of these
metal oxides were unexpected and allow applications of temperature sensitive substrates and organic
addenda. By coating very thin, almost or totally polymer-free layers of highly-porous, monodisperse
aluminum-oxides with minimum particle size, display devices with improved optical efficiency were
prepared. These layers have a low refractive index thus allowing for higher intensities of light emitted
by organic electro-luminescers in OLED’s and PLED’s. This property is useful for mobile devices as
phones and PDA’s. A hitherto unknown, photo-catalytic chemical reaction of the classical green
emitter tris-(8-hydroxychinolino)-aluminum (Alq3) has been discovered in coatings of such optically
efficient devices after exposing them to daylight in air. An efficient blue-emitting species of Alq3
with another stereochemical structure was directly formed within these layers at room temperature by
photolysis in ambient atmosphere. Interesting new applications of specially designed, large-area
coated and transparent nanostructured matrices on flexible substrates for optical gas sensors are
discussed in more detail in this paper.
Fabrication and Characterization of Carbon Nanofibers Carrying Ag Nanoparticles via Electrospinning
Authors: Li Z.Y. , Huang Hui Min , Wang C.
Published: March 2009

The carbon-nanofibers carrying Ag nanoparticles (Ag/CNF) have been successfully
obtained via electrospinning followed by calcination. For it, AgNO3/polyacrylonitrile (PAN) fibers
were firstly prepared as an intermediate and then the intermediate was calcined at 600°C for 4h to
transit the PAN nanofibers to the CNF and reduce AgNO3 to the Ag nanoparticles. Transmission
electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction
(XRD) were used to characterize their morphologies and structures. The results show that the
diameters of the Ag nanoparticles and CNF are 5 nm and 180 nm on the average, respectively. Most
of the Ag nanoparticles were located on the surface of carbon nanofibers.
Mechanism of Surface Dissolution in Dense Hydroxyapatite
Authors: Seo Dong Seok , Kim Hwan , Lee Jong Kook
Published: March 2009

In this study, it was demonstrated how second phases with small amount, which are hardly
detected by XRD analysis, affect grain boundary dissolution and related mechanical properties of HA.
All HA disks sintered at 1200 oC for 2 h in air with under moisture protection were phase pure and had
Ca/P molar ratio of 1.67. Following certain period of exposure to the distilled water, the surface
dissolution initiated at grain boundaries and particle loosening, subsequently resulting in decrease in
mechanical properties of HA. In order to understand the dissolution mechanism, grain boundary
structure of HA was identified by transmission electron microscopy (TEM) and high resolution TEM
observation. From the analysis, it was found that the non-stoichiometric phase as α-tricalcium
phosphate (TCP) transformed from β-TCP was existed at grain boundaries and caused surface
dissolution of HA. From the XRD analysis, it was found that (211) and (112) planes of hydroxyapatite
were susceptible to dissolution, whereas (300) plane was relatively stable.
Lanthanide-Clay Nanocomposites: Europium(III) Complexes Intercalated in Bentonite
Authors: Benavente Eglantina , Echeverría Yuri , Lavayen Vladimir , Sotomayor Torres Clivia M. , Gonzáles G.
Published: March 2009

The intercalation of [Eu(2,2 bipyridine)2 ]3+ and [Eu(1,10 phenantroline)2]3+ into bentonite
results in new nanocomposites which preserve the emission properties of the lanthanide. The
exchange of sodium by lanthanide in the bentonite correlates with the host cation exchange capacity
as well as with the guest molecular size and the interlaminar volume available in the clay. The
intercalated complexes exhibit luminescence indicating an efficient protecting role of the matrix.
This in turn points to lanthanide-clay nanocomposite as novel optical materials.
In-Situ Preparation of Highly Crystallized ZnO Nanopowders by Ultrasonic Spraying Combustion Method
Authors: Lee Nam Hee , Kim J.H. , Oh Hyo Jin , Kim Sun Jae
Published: March 2009

To obtain a mass production of nanocrystalline ZnO powders, equipment that combines the
conventional self-sustaining combustion process (SCP) with the ultrasonic spraying combustion
method (USCM) were applied. The droplet was sprayed into the reaction zone of the furnace to
carry out USCM that produces softly agglomerated crystalline ZnO particle with spherical shape.
It was confirmed that the ZnO powder was prepared from ultrasonic spraying combustion method
having smaller primary particle size, spherical shape with weak agglomeration and larger specific
surface area than from conventional self-sustaining combustion method. Synthesized
nanocrystalline ZnO powders have primary particle size in a range of 20∼30 nm, and specific
surface area of about 20 m2/g under the optimum ultrasonic spray conditions.
Preparing Mesoporous Silica Doped with Iron via a Novel Method
Authors: Liu H.D. , Chen Yun Fa
Published: March 2009

Mesoporous silica particles doped with iron was prepared with a novel method. Nitrogen
adsorption-desorption test indicated that the BET surface area decreased with the increasing of iron
doping amount. Small-angle X-ray diffractometry (SAXD) analysis showed that more iron dopant
gave rise to less orderly structured product. FITRanalysis were all carried out to study the iron
valent and distribution state in the as-made mesoporous silica particles.
Febrication of MWNTs Composites with In Situ Precipitation Method
Authors: Wang Jing , Kou Hua Min , Pan Yu Bai , Guo Jing Kun
Published: March 2009

In this article stable multi-walled carbon nanotubes (MWNTs) aqueous suspension with a
1.0 wt.% concentration was obtained with a very small quantity of dispersant. Precursor of ceramics
were synthesized in the suspension and densely deposited on the surface of MWNTs successfully by
a simple and effective in-situ precipitation method. The most important advantage for the in-situ
composite method is to make MWNTs homogeneously distributed in the matrix. The fully dense
compacts were obtained by spark-plasma-sintering (SPS) the in-situ precipitated composite powders
at temperature 200 oC lower than that of composite powders made from the traditional mixing
method. Furthermore, the microstructure and the mechanical property of the composites are much
better than that of traditional method. The in-situ precipitation could be a promising method to
fabricate CNTs composites of ceramics matrix especially those hard to sinter.
Protein Immobilization in PVA Hydrogel: A Synchrotron SAXS and FTIR Study
Authors: Mansur Herman S. , Mansur Alexandra A.P. , Oréfice R.L.
Published: March 2009

In the present work, we aimed to investigate the immobilization of Bovine Serum Albumin
(BSA) into poly (vinyl alcohol) (PVA) network. PVA hydrogels with BSA were characterized by
Synchrotron SAXS radiation associated with Fourier Transform Infrared Spectroscopy (FTIR). We
synthesized hydrogels by dissolving PVA in aqueous solution (5.0 wt%) and crosslinked with
glutaraldehyde (GA). PVA and PVA/GA hydrogels samples were immersed in BSA aqueous solution
for protein immobilization. FTIR spectra showed major vibration bands associated with PVA and GA
chemical groups, and BSA protein amides. Regarding to SAXS characterization, the slope of the log
I(q), scattering intensity, as a function of log q, the scattering vector, provided important information
about the morphology of entities present in the system. Two different scattering patterns were
obtained for PVA (slope = 3.5) and PVA/BSA (slope=1.5 and 3.0). These results have given strong
evidence of nano-ordered dispersed globular BSA immobilized into chemically crosslinked PVA
hydrogel network. SAXS analyses have indicated that the scattering q-vector maximum value was
shifted by altering PVA polymer hydrogel with GA crosslinker and also with BSA incorporation into
the network.
Nonlinear Optical Behaviour of PbS Nano-Particles
Authors: Zhang Y.D. , Cao B. , Zhang H.G. , Zhu Ji Jun
Published: March 2009

The third-order nonlinearities of PbS nano-dot and nano-belts have been investigated using
the Z-Scan technique with nanosecond laser pulses at 532nm. The effect of the PbS semiconductor
nanometer-size and spatial forms on the third-order optical nonlinearities and optical limiting
properties would be discussed when the nanometer-size were larger than the exciton size. The optical
limiting mechanism of materials was discussed in the nanosecond time domain.
Toward Electronic Conductance Characterization of DNA Nucleotide Bases
Authors: Krstić Predrag S. , Wells Jack C. , Fuentes-Cabrera Miguel , Xu Dong , Lee James Weifu
Published: March 2009

We calculate electron-transport properties within equilibrium, linear transport theory
through the DNA nucleotide bases spanning two gold nanowires. Our quantum mechanical
calculations show that single configurations of DNA bases A, C, T, and G have significantly
different charge conductance characteristics. This result is consistent with the notion that it is
possible to read the nucleotide base sequence on an individual DNA heteropolymer which is
moving through a gap between electrically biased nanoelectrodes by measuring the changes in the
electron-transport conductance.
Functionalization of Carbon Nanotube Surface via UV/O3 Treatment
Authors: Kim Jang Kyo , Sham Man Lung
Published: March 2009

The carbon nanotube (CNT) surface is successfully modified using the UV/Ozone
treatment and a triethylenetetramine (TETA) solution for use as the reinforcement for
polymer matrix nanocomposites. These treatments along with ultrasonication are aimed to
disperse the CNTs uniformly in the resin matrix, as well as to provide the CNT surface with
chemical functionalities for adhesion with resin. Fourier transform infra-red (FTIR)
spectroscopy and X-ray photoelectron spectroscopy (XPS) are performed to evaluate the
changes in chemical structure and surface functional groups arising from the chemical
treatment. The practical implications of the surface functional groups for improving the
interfacial adhesion are discussed.
Influence of Carbon Nanofibers and Piezoelectric Particles on the Thermomechanical Behaviour of Epoxy Mixtures
Authors: Tsantzalis S. , Tsotra P. , Karapappas P. , Vavouliotis A. , Fanis N. , Kostopoulos Vassilis , Friedrich Klaus
Published: March 2009

Vapor growth carbon nanofibers (CNFs), lead zirconate titanate piezoelectric
(PZT) particles, as well as a combination of these two were added in an epoxy resin
(EP), and their influence on the curing reaction was investigated. Moreover, the cured
samples were characterised by dynamic scanning calorimetry and dynamic thermal
mechanical analysis. The presence of the fillers had no significant effect of the curing
reaction of the EP system and the glass transition temperature, Tg.