Abstract: Synthesis of gold nanoparticles has attracted much
attention since the pioneering discovery of the high catalytic activity
of supported gold nanoparticles in the reaction of CO oxidation at
low temperature. In this research field, we used Na-montmorillonite
for gold nanoparticles stabilization; various gold loading percentage
1, 2 and 5% were used for gold nanoparticles preparation. The gold
nanoparticles were obtained using chemical reduction method using
NaBH4 as reductant agent. The obtained gold nanoparticles stabilized
in Na-montmorillonite were used as catalysts for the reduction of 4-
nitrophenol to aminophenol with sodium borohydride at room
temperature. The UV-Vis results confirmed directly the gold
nanoparticles formation. The XRD and N2 adsorption results showed
the formation of gold nanoparticles in the pores of montmorillonite
with an average size of 5 nm obtained on samples with 2% gold
loading percentage. The gold particles size increased with the
increase of gold loading percentage. The reduction reaction of 4-
nitrophenol into 4-aminophenol with NaBH4 catalyzed by Au-Namontmorillonite
catalyst exhibits remarkably a high activity; the
reaction was completed within 9 min for 1%Au-Na-montmorillonite
and within 3 min for 2%Au-Na-montmorillonite.
Abstract: In the present study, the properties of Al-Al2O3
nanocomposite hollow sphere structures were investigated. For this
reason, the Al-based nanocomposite hollow spheres with different
amounts of nano-alumina reinforcement (0-10wt %) and different
ratio of thickness to diameter (t/D: 0.06-0.3) were prepared via a
powder metallurgy method. Then, the effect of mentioned parameters
was studied on physical and quasi static mechanical properties of
their related prepared structures (open/closed cell) such as density,
hardness, strength, and energy absorption. It was found that, as the
t/D ratio increases the relative density, compressive strength and
energy absorption increase. The highest values of strength and energy
absorption were obtained from the specimen with 5 wt. % of
nanoparticle reinforcement, t/D of 0.3 (t=1 mm, D=400μm) as 22.88
MPa and 13.24 MJ/m3, respectively. The moderate specific strength
of prepared composites in the present study showed the good
consistency with the properties of others low carbon steel composite
with similar structure.
Abstract: Particle size distribution, the most important
characteristics of aerosols, is obtained through electrical
characterization techniques. The dynamics of charged nanoparticles
under the influence of electric field in Electrical Mobility
Spectrometer (EMS) reveals the size distribution of these particles.
The accuracy of this measurement is influenced by flow conditions,
geometry, electric field and particle charging process, therefore by
the transfer function (transfer matrix) of the instrument. In this work,
a wire-cylinder corona charger was designed and the combined fielddiffusion
charging process of injected poly-disperse aerosol particles
was numerically simulated as a prerequisite for the study of a
multichannel EMS. The result, a cloud of particles with no uniform
charge distribution, was introduced to the EMS. The flow pattern and
electric field in the EMS were simulated using Computational Fluid
Dynamics (CFD) to obtain particle trajectories in the device and
therefore to calculate the reported signal by each electrometer.
According to the output signals (resulted from bombardment of
particles and transferring their charges as currents), we proposed a
modification to the size of detecting rings (which are connected to
electrometers) in order to evaluate particle size distributions more
accurately. Based on the capability of the system to transfer
information contents about size distribution of the injected particles,
we proposed a benchmark for the assessment of optimality of the
design. This method applies the concept of Von Neumann entropy
and borrows the definition of entropy from information theory
(Shannon entropy) to measure optimality. Entropy, according to the
Shannon entropy, is the ''average amount of information contained in
an event, sample or character extracted from a data stream''.
Evaluating the responses (signals) which were obtained via various
configurations of detecting rings, the best configuration which gave
the best predictions about the size distributions of injected particles,
was the modified configuration. It was also the one that had the
maximum amount of entropy. A reasonable consistency was also
observed between the accuracy of the predictions and the entropy
content of each configuration. In this method, entropy is extracted
from the transfer matrix of the instrument for each configuration.
Ultimately, various clouds of particles were introduced to the
simulations and predicted size distributions were compared to the
exact size distributions.
Abstract: An experimental investigation is carried out to
establish the performance characteristics of a compression ignition
engine while using cerium oxide nanoparticles as additive in neat
diesel and diesel-biodiesel blends. In the first phase of the
experiments, stability of neat diesel and diesel-biodiesel fuel blends
with the addition of cerium oxide nanoparticles is analyzed. After
series of experiments, it is found that the blends subjected to high
speed blending followed by ultrasonic bath stabilization improves the
stability. In the second phase, performance characteristics are studied
using the stable fuel blends in a single cylinder four stroke engine
coupled with an electrical dynamometer and a data acquisition
system. The cerium oxide acts as an oxygen donating catalyst and
provides oxygen for combustion. The activation energy of cerium
oxide acts to burn off carbon deposits within the engine cylinder at
the wall temperature and prevents the deposition of non-polar
compounds on the cylinder wall results reduction in HC emissions.
The tests revealed that cerium oxide nanoparticles can be used as
additive in diesel and diesel-biodiesel blends to improve complete
combustion of the fuel significantly.
Abstract: The use of engineered nanomaterials has increased as
a result of their positive impact on many sectors of the economy,
including agriculture. Silver nanoparticles (AgNPs) are now used to
enhance seed germination, plant growth, and photosynthetic quantum
efficiency and as antimicrobial agents to control plant diseases. In
this study, we examined the effect of AgNP dosage on the seed
germination of three plant species: corn (Zea mays L.), watermelon
(Citrullus lanatus [Thunb.] Matsum. & Nakai) and zucchini
(Cucurbita pepo L.). This experiment was designed to study the
effect of AgNPs on germination percentage, germination rate, mean
germination time, root length and fresh and dry weight of seedlings
for the three species. Seven concentrations (0.05, 0.1, 0.5, 1, 1.5, 2
and 2.5 mg/ml) of AgNPs were examined at the seed germination
stage. The three species had different dose responses to AgNPs in
terms of germination parameters and the measured growth
characteristics. The germination rates of the three plants were
enhanced in response to AgNPs. Significant enhancement of the
germination percentage values was observed after treatment of the
watermelon and zucchini plants with AgNPs in comparison with
untreated seeds. AgNPs showed a toxic effect on corn root
elongation, whereas watermelon and zucchini seedling growth were
positively affected by certain concentrations of AgNPs. This study
showed that exposure to AgNPs caused both positive and negative
effects on plant growth and germination.
Abstract: Polyaniline is an indispensible component in lightemitting
devices (LEDs), televisions, cellular telephones, automotive,
corrosion-resistant coatings, actuators etc. The electrical conductivity
properties was found be increased by introduction of metal nano
particles. In the present study, an attempt has been made to utilize
platinum nano particles to achieve the improved electrical properties.
Polyaniline and Pt-polyaniline composite are synthesized by
electrochemical routes. X-ray diffractometer confirms the amorphous
nature of polyaniline. The Bragg’s diffraction peaks correspond to
platinum nanoparticles in Pt-polyaniline composite and
thermogravimetric analyzer indicates its decomposition at certain
temperature. The Scanning Electron Micrographs of colloidal
platinum nanoparticles were spherical, uniform shape in the
composite. The current-voltage (I-V) characteristics of the PANI and
composites were also studied which indicate a significant decreasing
resistivity than PANI-Platinum after introduction of pt nanoparticles
in the matrix of polyaniline (PANI).
Abstract: Nanotechnology has become the world attention in
various applications including the solar cells devices due to the
uniqueness and benefits of achieving low cost and better
performances of devices. Recently, thin film solar cells such as
Cadmium Telluride (CdTe), Copper-Indium-Gallium-diSelenide
(CIGS), Copper-Zinc-Tin-Sulphide (CZTS), and Dye-Sensitized
Solar Cells (DSSC) enhanced by nanotechnology have attracted
much attention. Thus, a compilation of nanotechnology devices
giving the progress in the solar cells has been presented. It is much
related to nanoparticles or nanocrystallines, carbon nanotubes, and
nanowires or nanorods structures.
Abstract: Zn alloy and composite coatings are widely used in
buildings and structures, automobile and fasteners industries to
protect steel component from corrosion. In this paper, Zn-Ni-Al2O3
nanocomposite coatings were electrodeposited on mild steel using a
novel sol enhanced electroplating method. In this method, transparent
Al2O3 sol was added into the acidic Zn-Ni bath to produced Zn-Ni-
Al2O3 nanocomposite coatings. The effect of alumina sol on the
electrodeposition process, and coating properties was investigated
using cyclic voltammetry, XRD, ESEM and Tafel test. Results from
XRD tests showed that the structure of all coatings was single γ-
Ni5Zn21 phase. Cyclic voltammetry results showed that the
electrodeposition overpotential was lower in the presence of alumina
sol in the bath, and caused the reduction potential of Zn-Ni to shift to
more positive values. Zn-Ni-Al2O3 nanocomposite coatings produced
more uniform and compact deposits, with fine grained microstructure
when compared to Zn-Ni coatings. The corrosion resistance of Zn-Ni
coatings was improved significantly by incorporation of alumina
nanoparticles into the coatings.
Abstract: In this work new macroporous Ni electrodes modified
with Au nanoparticles for hydrogen production have been developed.
The supporting macroporous Ni electrodes have been obtained by
means of the electrodeposition at high current densities. Then, the Au
nanoparticles were synthesized and added to the electrode surface.
The electrocatalytic behaviour of the developed electrocatalysts was
studied by means of pseudo-steady-state polarization curves,
electrochemical impedance spectroscopy (EIS) and hydrogen
discharge curves. The size of the Au synthetized nanoparticles shows
a monomodal distribution, with a very sharp band between 10 and 50
nm. The characteristic parameters d10, d50 and d90 were 14, 20 and
31 nm respectively. From Tafel polarization data has been concluded
that the Au nanoparticles improve the catalytic activity of the
developed electrodes towards the HER respect to the macroporous Ni
electrodes. EIS permits to obtain the electrochemically active area by
means of the roughness factor value. All the developed electrodes
show roughness factor values in the same order of magnitude. From
the activation energy results it can be concluded that the Au
nanoparticles improve the intrinsic catalytic activity of the
macroporous Ni electrodes.
Abstract: In this study, the experiments were carried out to
determine the best coolant for the quenching process among waterbased
silica, alumina, titania and copper oxide nanofluids (0.1 vol%).
A sphere made up off brass material was used in the experiments.
When the spherical test specimen was heated at high temperatures, it
was suddenly immersed into the nanofluids. All experiments were
carried out at saturated conditions and under atmospheric pressure.
After the experiments, the cooling curves were obtained by using the
temperature-time data of the specimen. The experimental results
showed that the cooling performance of test specimen depended on
the type of nanofluids. The silica nanoparticles enhanced the
performance of boiling heat transfer and it is the best coolant for the
quenching among other nanoparticles.
Abstract: Doxorubicin (DOX) is an anthracycline drug used to treat many cancer diseases. Similarly to other cytostatic drugs, DOX has serious side effects; the biggest obstacle is the cardiotoxicity. With the aim of lowering the negative side effects and to target the DOX into the tumor tissue, the different nanoparticles (NPs) are studied. The aim of this work was to synthetized different NPs and conjugated them with DOX and determine the binding capacity of the NPs. For this experiment, carbon nanotubes (CNTs), graphene oxide (GO), fullerene (FUL) and liposomes (LIP) were used. The highest binding capacity was observed in GO (85%). Subsequently the toxicity of NPs and NPs-DOX conjugates was analyzed in in vivo system (chicken embryos). Some NPs (GO) can increase the toxicity of DOX, whereas other NPs (LIP, CNTs) decrease DOX toxicity.
Abstract: To ensure targeting of apoferritin nanocarrier with
encapsulated doxorubicin drug, we used a peptide linker based on a
protein G with N-terminus affinity towards Fc region of antibodies.
To connect the peptide to the surface of apoferritin, the C-terminus of
peptide was made of cysteine with affinity to gold. The surface of
apoferritin with encapsulated doxorubicin (APODOX) was coated
either with gold nanoparticles (APODOX-Nano) or gold(III) chloride
hydrate reduced with sodium borohydride (APODOX-HAu). The
reduction with sodium borohydride caused a loss of doxorubicin
fluorescent properties and probably accompanied with the loss of its
biological activity. Fluorescent properties of APODOX-Nano were
similar to the unmodified APODOX; therefore it was more suited for
the intended use. To evaluate the specificity of apoferritin modified
with antibodies, ELISA-like method was used with the surface of
microtitration plate wells coated by the antigen (goat anti-human IgG
antibodies). To these wells, the nanocarrier was applied. APODOX
without the modification showed 5× lower affinity to the antigen than
APODOX-Nano modified gold and targeting antibodies (human IgG
antibodies).
Abstract: The novel 3D SnO cabbages self-assembled by
nanosheets were successfully synthesized via template-free
hydrothermal growth method under facile conditions. The XRD
results manifest that the as-prepared SnO is tetragonal phase. The
TEM and HRTEM results show that the cabbage nanosheets are
polycrystalline structure consisted of considerable single-crystalline
nanoparticles. Two typical Raman modes A1g=210 and Eg=112 cm-1
of SnO are observed by Raman spectroscopy. Moreover, galvanostatic
cycling tests has been performed using the SnO cabbages as anode
material of lithium ion battery and the electrochemical results suggest
that the synthesized SnO cabbage structures are a promising anode
material for lithium ion batteries.
Abstract: Development of new generation bio-tribological,
multilayer coatings opens an avenue for fabrication of future hightech
functional surfaces. In the presented work, nano-composite,
Cr/CrN+[Cr/ a-C:H implanted by metallic nanocrystals] multilayer
coatings have been developed for surface protection of medical tools.
Thin films were fabricated by a hybrid Pulsed Laser Deposition
technique. Complex microstructure analysis of nanomultilayer
coatings, subjected to mechanical and biological tests, were
performed by means of transmission electron microscopy (TEM).
Microstructure characterization revealed the layered arrangement of
Cr23C6 nanoparticles in multilayer structure. Influence of deposition
conditions on bio-tribological properties of the coatings was studied.
The bio-tests were used as a screening tool for the analyzed
nanomultilayer coatings before they could be deposited on medical
tools. Bio-medical tests were done using fibroblasts. The mechanical
properties of the coatings were investigated by means of a ball-ondisc
mechanical test. The micro hardness was done using Berkovich
indenter. The scratch adhesion test was done using Rockwell
indenter. From the bio-tribological point of view, the optimal
properties had the C106_1 material.
Abstract: We present a gas-liquid microfluidic system as a
reactor to obtain magnetite nanoparticles with an excellent degree of
control regarding their crystalline phase, shape and size. Several
types of microflow approaches were selected to prevent nanomaterial
aggregation and to promote homogenous size distribution. The
selected reactor consists of a mixer stage aided by ultrasound waves
and a reaction stage using a N2-liquid segmented flow to prevent
magnetite oxidation to non-magnetic phases. A milli-fluidic reactor
was developed to increase the production rate where a magnetite
throughput close to 450 mg/h in a continuous fashion was obtained.
Abstract: Electrodeposition is a simple and economic technique
for precision coating of different shaped substrates with pure metal,
alloy or composite films. Dc electrodeposition was used to produce
Cr, Co-Cr and Co-Cr/TiO2 nano-composite coatings from Cr(III)
based electrolytes onto 316L SS substrates. The effects of TiO2 nanoparticles
concentration on co-deposition of these particles along with
Cr content and microhardness of the coatings were investigated.
Morphology of the Cr, Co-Cr and Co-Cr/TiO2 coatings besides their
tribological behavior were studied. The results showed that increment
of TiO2 nanoparticles concentration from 0 to 30 g L-1 in the bath
increased their co-deposition and Cr content of the coatings from 0 to
3.5 wt.% and from 23.7 to 31.2 wt.%, respectively. Microhardness of
Cr coating was about 920 Hv which was higher than Co-Cr and even
Co-Cr/TiO2 films. Microhardness of Co-Cr and Co-Cr/TiO2 coatings
were improved by increasing their Cr and TiO2 content. All the
coatings had nodular morphology and contained microcracks.
Nodules sizes and the number of microcracks in the alloy and
composite coatings were lower than the Cr film. Wear results
revealed that the Co-Cr/TiO2 coating had the lowest wear loss
between all the samples, while the Cr film had the worst wear
resistance.
Abstract: Heat transfer due to forced convection of copper water
based nanofluid has been predicted by Artificial Neural network
(ANN). The present nanofluid is formed by mixing copper
nanoparticles in water and the volume fractions are considered here
are 0% to 15% and the Reynolds number are kept constant at 100.
The back propagation algorithm is used to train the network. The
present ANN is trained by the input and output data which has been
obtained from the numerical simulation, performed in finite volume
based Computational Fluid Dynamics (CFD) commercial software
Ansys Fluent. The numerical simulation based results are compared
with the back propagation based ANN results. It is found that the
forced convection heat transfer of water based nanofluid can be
predicted correctly by ANN. It is also observed that the back
propagation ANN can predict the heat transfer characteristics of
nanofluid very quickly compared to standard CFD method.
Abstract: Chitosan functionalized Fe3O4-Au core shell
nanoparticles have been prepared using a two-step wet chemical
approach using NaBH4 as reducing agent for formation of Au in
ethylene glycol. X-ray diffraction studies shows individual phases of
Fe3O4 and Au in the as prepared samples with crystallite size of 5.9
and 11.4 nm respectively. The functionalization of the core-shell
nanostructure with Chitosan has been confirmed using Fourier
transform infrared spectroscopy along with signatures of octahedral
and tetrahedral sites of Fe3O4 below 600cm-1. Mössbauer
spectroscopy shows decrease in particle-particle interaction in
presence of Au shell (72% sextet) than pure oleic coated Fe3O4
nanoparticles (88% sextet) at room temperature. At 80K, oleic acid
coated Fe3O4 shows only sextets whereas the Chitosan functionalized
Fe3O4 and Chitosan functionalized Fe3O4@Au core shell show
presence of 5 and 11% doublet, respectively.
Abstract: Plasmin plays an important role in the human
circulatory system owing to its catalytic ability of fibrinolysis. The
immediate injection of plasmin in patients of strokes has intrigued
many scientists to design vectors that can transport plasmin to the
desired location in human body. Here we predict the structure of
human plasmin and investigate the interaction of plasmin with the
gold-nanoparticle.
Because the crystal structure of plasminogen has been solved, we
deleted N-terminal domain (Pan-apple domain) of plasminogen and
generate a mimic of the active form of this enzyme (plasmin). We
conducted a simulated annealing process on plasmin and discovered a
very large conformation occurs. Kringle domains 1, 4 and 5 had been
observed to leave its original location relative to the main body of the
enzyme and the original doughnut shape of this enzyme has been
transformed to a V-shaped by opening its two arms. This observation
of conformational change is consistent with the experimental results of
neutron scattering and centrifugation.
We subsequently docked the plasmin on the simulated gold surface
to predict their interaction. The V-shaped plasmin could utilize its
Kringle domain and catalytic domain to contact the gold surface.
Our findings not only reveal the flexibility of plasmin structure but
also provide a guide for the design of a plasmin-gold nanoparticle.
Abstract: The use of engineered nanomaterials has increased as
a result of their positive impact on many sectors of the economy,
including agriculture. Silver nanoparticles (AgNPs) are now used to
enhance seed germination, plant growth, and photosynthetic quantum
efficiency and as antimicrobial agents to control plant diseases. In
this study, we examined the effect of AgNP dosage on the seed
germination of three plant species: corn (Zea mays L.), watermelon
(Citrullus lanatus [Thunb.] Matsum. & Nakai) and zucchini
(Cucurbita pepo L.). This experiment was designed to study the
effect of AgNPs on germination percentage, germination rate, mean
germination time, root length and fresh and dry weight of seedlings
for the three species. Seven concentrations (0.05, 0.1, 0.5, 1, 1.5, 2
and 2.5 mg/ml) of AgNPs were examined at the seed germination
stage. The three species had different dose responses to AgNPs in
terms of germination parameters and the measured growth
characteristics. The germination rates of the three plants were
enhanced in response to AgNPs. Significant enhancement of the
germination percentage values was observed after treatment of the
watermelon and zucchini plants with AgNPs in comparison with
untreated seeds. AgNPs showed a toxic effect on corn root
elongation, whereas watermelon and zucchini seedling growth were
positively affected by certain concentrations of AgNPs. This study
showed that exposure to AgNPs caused both positive and negative
effects on plant growth and germination.