Abstract: An improved technique to fabricate PMMA/Ag core-shell nanocomposite via a two-step
procedure is reported. The procedure includes an improved particle surface treatment and an
improved, subsequent Ag reduction reaction strategy. Well-dispersed PMMA/Ag core-shell
nanoparticles with uniform particle size distribution were successfully fabricated using this
improved technique. Different functional group treatment on the PMMA particle surface led to an
electronically graded transition from the covalent bond of PMMA core to the metallic bond of silver
shell. The improved fabrication technique thus allows a highly tailorable size of PMMA core and
controllable thickness of Ag shell, which is crucial to producing a tunable plasmon resonance signal
to different bio-/chem-environments.
Abstract: Fabrication, optical property of nano coreshells and their potential applications in
chemical and biological sensors have attracted much research interest. In this paper, we simulated
the effect of size, structure, and dielectric properties as well embedding medium on the optical
properties of gold or silver coated coreshell nanoparticle and the corresponding effects both of
phase-retardation and of electron interface scattering as well as the nansize effect were discussed.
Intriguing transition of the optical properties was simulated when a two-phase core-shell
nanoparticle changes gradually into the single phase nanoparticle. We also obtained a good
correlation of the simulation to the experimental results. Thus, the simulation has many implications
and can guide further core-shell nanostructure fabrication with optimization of its optical properties.
Abstract: Fe/Pt bimetallic nanoparticles at various molar ratios have been prepared by
simultaneous reduction of FeCl2 and H2PtCl6 with hydrazine hydrate in water/Triton X-
100/cyclohexane/pentanol microemulsions at room temperature. The size, structure, composition
and the magnetic properties of the resultant nanoparticles were characterized by XRD, EDX, TEM
and AGM. XRD patterns indicated the formation of face centered cubic FePt nanoparticles with
crystallite size in the range of 4 nm to 8 nm. Higher content of iron resulted in larger FePt
nanoparticles. EDX analyses on the samples confirmed the presence of Fe and Pt elements in the
particle. The composition for each particle was roughly consistent with the Fe2+ to Pt 4+ ratio of
initial solution. TEM micrograph showed homogeneous fine spherical particles. The physical sizes
were similar to the crystallite sizes of FePt nanoparticles calculated from XRD. The Fe/Pt molar
ratio of 1 to 1 showed optimum magnetic properties with coercivity (Hc) of 68.67 Oe .
Abstract: A new, direct method has been developed to measure the adhesion forces of bovine
serum albumin (BSA) on surfaces by using Atomic Force Microscopy (AFM) in liquid environment.
We were able to measure interactions between proteins and substrate surface in PBS solution
directly without any modification to the substrate or the AFM tip. Two different surfaces have been
used in the experiments: mica (hydrophilic surface) and polystyrene (hydrophobic surface). The
results show that a polystyrene surface is more adhesive to BSA than a mica surface. This is
consistent with previous research, which assessed that hydrophobic surfaces enhance protein
adhesion but hydrophilic surfaces do not, demonstrating the effectiveness of the technique.
Abstract: This paper reviews our systematic and exhaustive studies on the lead zirconate titanate
doped with dopants using ab initio density functional theory calculations in order to understand the
mechanisms behind the dopings. Different candidates of dopants were selected by screening the
periodical table of elements. In our studies, group VA, VIA elements (B-site donors), group IIA
elements (A-site donors), group IIIB elements (B-site acceptors), and group VB elements (A-site
donor, B-site acceptor/donors) are investigated as dopants in PZT. We found that there exist
different mechanisms behind the improved ferroelectric properties, especially the fatigue behaviors.
For donors doping, diluted oxygen vacancy concentration and reduced electronic suppression of
polarization contribute to the fatigue-free behaviors of donor doped PZT. On the other hand, for
acceptor doping, acceptor-oxygen-vacancy-acceptor clusters are energetically preferred, which
greatly reduce the oxygen vacancy mobility and the domain pinning effects. We expect that this
study could provide important information for the experiments on PZT-based materials.
Abstract: In this study, the stress-strain distributions and interface failure in a BGA (Ball Grid
Array) package subjected to thermal cycling were investigated using 2D and 3D finite element
analyses. The viscous behavior of the adhesive material and thermal mismatch between the
dissimilar materials in the package were considered. The potential failure sites in the solider and
adhesive joints were analyzed.
Abstract: Arc ion plating(AIP) has higher deposition rates, whereas macro-particles (MPs) make
the film properties decreasing. In this paper, AIP with or without magnetic filter (MF or AIP) and
composition of AIP followed with magnetic filter (MFAIP) were designed to deposit TiN films on
silicon (Si) and high-speed steel(HSS), respectively. Scanning electron microscope (SEM),
nanoindentation and microscratch tests were investigated. SEM showed that both the MF and the
MFAIP films had a superfine layer among the columnar crystals grown vertically against substrate
surface. However, the columnar crystals of MF films were leptosomatic and well-orientational,
while MFAIP ones were coarse and short, and even ragged in size and orientation. Nanoindentation
test results showed the highest hardness for MF films and the lowest one for AIP films. A new
parameter Scratch Crack Propagation Resistance (CPRs) was introduced to evaluate the film
adhesion properties in a scratch test. MF films had the highest adhesion. AIP films were most
susceptible to failure as the CPRs was the lowest, although the Lc1 was higher than MFAIP ones. It
was proposed that the MPs were effectively removed with the MF, and the MF layers were
superfine to improve the properties of the films.
Abstract: Erosion corrosion and environmental chamber corrosion studies conducted on plasma
sprayed samples from three different spray dried and densified nanopowders showed good
resistance to corrosion. A dense, uniform and even distribution of splats and small number of
microvoids and pores offered a high resistance to erosion-corrosion in sodium chloride polystyrene
slurry. The coatings offer a high resistance in salt spray chamber environment.
Abstract: To combine the merits of both metals and ceramics into one material, many researchers
have been studying the deposition of alumina coating using plasma spray on metal substrates.
However, as the coatings are deposited at a high temperature, residual thermal stresses develop due to
the mismatch of thermal expansion coefficients of the coating and substrate and these are responsible
for the initiation and expansion of cracks, which induce the possible failure of the entire material. In
this paper, the residual thermal-structural analysis of a Fe3Al/Al2O3 gradient coating on carbon steel
substrate is performed using finite element modelling to simulate the plasma spray. The residual
thermal stress fields are obtained and analyzed on the basis of temperature fields in gradient coatings
during fabrication. The distribution of residual thermal stresses including radial, axial and shear
stresses shows stress concentration at the interface between the coatings and substrate. The mismatch
between steel substrate and composite coating is still the dominant factor for the residual stresses.
Abstract: Subsurface residual stresses of tungsten films induced by Chemical Mechanical Polishing
(CMP) processes were investigated by the Grazing Incident X-Ray Diffraction (GIXRD). Basis of the
GIXRD measurement was introduced and the experiments were conducted for residual stress of
tungsten film measurements. Experimental procedures of the GIXRD measurements were presented.
The obtained residual stresses value of tungsten films from 800 nm to 400 nm varies from 1086.1 ±
105.2 MPa to 1670.6±103.4 MPa prior and after CMP process.