Abstract: Silver nanoparticles were prepared by chemical reduction method. Silver nitrate was taken as the metal precursor and hydrazine hydrate as a reducing agent. The formation of the silver nanoparticles was monitored using UV-Vis absorption spectroscopy. The UV-Vis spectroscopy revealed the formation of silver nanopart├¡cles by exhibing the typical surface plasmon absorption maxima at 418-420 nm from the UV–Vis spectrum. Comparison of theoretical (Mie light scattering theory) and experimental results showed that diameter of silver nanoparticles in colloidal solution is about 60 nm. We have used energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and, UV–Vis spectroscopy to characterize the nanoparticles obtained. The energy-dispersive spectroscopy (EDX) of the nanoparticles dispersion confirmed the presence of elemental silver signal no peaks of other impurity were detected. The average size and morphology of silver nanoparticles were determined by transmission electron microscopy (TEM). TEM photographs indicate that the nanopowders consist of well dispersed agglomerates of grains with a narrow size distribution (40 and 60 nm), whereas the radius of the individual particles are between 10 and 20 nm. The synthesized nanoparticles have been structurally characterized by X-ray diffraction and transmission high-energy electron diffraction (HEED). The peaks in the XRD pattern are in good agreement with the standard values of the face-centered-cubic form of metallic silver (ICCD-JCPDS card no. 4-0787) and no peaks of other impurity crystalline phases were detected. Additionally, the antibacterial activity of the nanopart├¡culas dispersion was measured by Kirby-Bauer method. The nanoparticles of silver showed high antimicrobial and bactericidal activity against gram positive bacteria such as Escherichia Coli, Pseudimonas aureginosa and staphylococcus aureus which is a highly methicillin resistant strain.
Abstract: The expression of LFA-1 diverges from the
physiological condition, thus active targeting carrier can provide the
benefits from difference into LFA-1 expression in various conditions.
Here, the selectivity of cIBR-conjugated nanoparticles (cIBR-NPs),
in terms of uptake, was investigated using PBMCs, Mixed PBMCMolt-
3 cells and Molt-3 cells. The expressions of LFA-1 on Molt-3
cells, from flow cytometry and Western blot, possessed the highest
level whereas PBMCs showed the lowest level. The kinetic uptake
profiles of cIBR-NPs were obtained by flow cytometry, which the
degree of cellular uptake presented a similar trend with the level of
LFA-1 indicating the influence of LFA-1 expression on the cellular
uptake of cIBR-NPs. The conformation of LFA-1 had a slight effect
on the cellular uptake of cIBR-NPs. Overall we demonstrated that
cIBR-NPs enhanced cellular uptake and improved the selectivity of
drug carriers to LFA-1 on the leukemia cells, which related with the
order of LFA-1 expression.
Abstract: Blood pulse is an important human physiological signal commonly used for the understanding of the individual physical health. Current methods of non-invasive blood pulse sensing require direct contact or access to the human skin. As such, the performances of these devices tend to vary with time and are subjective to human body fluids (e.g. blood, perspiration and skin-oil) and environmental contaminants (e.g. mud, water, etc). This paper proposes a simulation model for the novel method of non-invasive acquisition of blood pulse using the disturbance created by blood flowing through a localized magnetic field. The simulation model geometry represents a blood vessel, a permanent magnet, a magnetic sensor, surrounding tissues and air in 2-dimensional. In this model, the velocity and pressure fields in the blood stream are described based on Navier-Stroke equations and the walls of the blood vessel are assumed to have no-slip condition. The blood assumes a parabolic profile considering a laminar flow for blood in major artery near the skin. And the inlet velocity follows a sinusoidal equation. This will allow the computational software to compute the interactions between the magnetic vector potential generated by the permanent magnet and the magnetic nanoparticles in the blood. These interactions are simulated based on Maxwell equations at the location where the magnetic sensor is placed. The simulated magnetic field at the sensor location is found to assume similar sinusoidal waveform characteristics as the inlet velocity of the blood. The amplitude of the simulated waveforms at the sensor location are compared with physical measurements on human subjects and found to be highly correlated.
Abstract: Carbon nanotubes (CNTs) possess unique structural,
mechanical, thermal and electronic properties, and have been
proposed to be used for applications in many fields. However, to
reach the full potential of the CNTs, many problems still need to be
solved, including the development of an easy and effective
purification procedure, since synthesized CNTs contain impurities,
such as amorphous carbon, carbon nanoparticles and metal particles.
Different purification methods yield different CNT characteristics
and may be suitable for the production of different types of CNTs. In
this study, the effect of different purification chemicals on carbon
nanotube quality was investigated. CNTs were firstly synthesized by
chemical vapor deposition (CVD) of acetylene (C2H2) on a
magnesium oxide (MgO) powder impregnated with an iron nitrate
(Fe(NO3)3·9H2O) solution. The synthesis parameters were selected
as: the synthesis temperature of 800°C, the iron content in the
precursor of 5% and the synthesis time of 30 min. The liquid phase
oxidation method was applied for the purification of the synthesized
CNT materials. Three different acid chemicals (HNO3, H2SO4, and
HCl) were used in the removal of the metal catalysts from the
synthesized CNT material to investigate the possible effects of each
acid solution to the purification step. Purification experiments were
carried out at two different temperatures (75 and 120 °C), two
different acid concentrations (3 and 6 M) and for three different time
intervals (6, 8 and 15 h). A 30% H2O2 : 3M HCl (1:1 v%) solution
was also used in the purification step to remove both the metal
catalysts and the amorphous carbon. The purifications using this
solution were performed at the temperature of 75°C for 8 hours.
Purification efficiencies at different conditions were evaluated by
thermogravimetric analysis. Thermal and electrical properties of
CNTs were also determined. It was found that the obtained electrical
conductivity values for the carbon nanotubes were typical for organic
semiconductor materials and thermal stabilities were changed
depending on the purification chemicals.
Abstract: In the present study, Convective heat transfer
coefficient and pressure drop of Al2O3/water nanofluid in laminar
flow regime under constant heat flux conditions inside a circular tube
were experimentally investigated. Al2O3/water nanofluid with 0.5%
and 1% volume concentrations with 15 nm diameter nanoparticles
were used as working fluid. The effect of different volume
concentrations on convective heat transfer coefficient and friction
factor was studied. The results emphasize that increasing of particle
volume concentration leads to enhance convective heat transfer
coefficient. Measurements show the average heat transfer coefficient
enhanced about 11-20% with 0.5% volume concentration and
increased about 16-27% with 1% volume concentration compared to
distilled water. In addition, the convective heat transfer coefficient of
nanofluid enhances with increase in heat flux. From the results, the
average ratio of (fnf/fbf) was about 1.10 for 0.5% volume
concentration. Therefore, there is no significant increase in friction
factor for nanofluids.
Abstract: The aims of this paper are to study the efficacy of
chitosan nanoparticles in stimulating specific antibody against
A/H1N1 influenza antigen in mice. Chitosan nanoparticles (CSN)
were characterized by TEM. The results showed that the average size
of CSN was from 80nm to 106nm. The efficacy of A/H1N1 influenza
vaccine loaded on the surface of CSN showed that loading efficiency
of A/H1N1 influenza antigen on CSN was from 93.75 to 100%. Safe
property of the vaccine were tested. In 10 days post vaccination,
group of CSN 30 kDa and 300 kDa loaded A/H1N1 influenza antigen
were the rate of immune response on mice to be 100% (9/9) higher
than Al(OH)3 and other adjuvant. 100% mice in the experiment of all
groups had immune response in 20 days post vaccination. The results
also showed that HI titer of the group using CSN 300 kDa as an
adjuvant increased significantly up to 3971 HIU, over three-fold
higher than the Al(OH)3 adjuvant, chitosan (CS), and one hundredfold
than the A/H1N1 antigen only. Stability of the vaccine
formulation was investigated.
Abstract: In this study we applied thermal lens (TL) technique
to study the effect of size on thermal diffusivity of cadmium sulphide
(CdS) nanofluid prepared by using γ-radiation method containing
particles with different sizes. In TL experimental set up a diode laser
of wavelength 514 nm and intensity stabilized He-Ne laser were used
as the excitation source and the probe beam respectively,
respectively. The experimental results showed that the thermal
diffusivity value of CdS nanofluid increases when the of particle size
increased.
Abstract: We have developed a microfluidic device system for the continuous producting of nanoparticles, and we have clarified the relationship between the mixing performance of reactors and the particle size. First, we evaluated the mixing performance of reactors by carring out the Villermaux–Dushman reaction and determined the experimental conditions for producing AgCl nanoparticles. Next, we produced AgCl nanoparticles and evaluated the mixing performance and the particle size. We found that as the mixing performance improves the size of produced particles decreases and the particle size distribution becomes sharper. We produced AgCl nanoparticles with a size of 86 nm using the microfluidic device that had the best mixing performance among the three reactors we tested in this study; the coefficient of variation (Cv) of the size distribution of the produced nanoparticles was 26.1%.
Abstract: A numerical study has been carried out to investigate
the heat transfer by natural convection of nanofluid taking Cu as
nanoparticles and the water as based fluid in a three dimensional
annulus enclosure filled with porous media (silica sand) between two
horizontal concentric cylinders with 12 annular fins of 2.4mm
thickness attached to the inner cylinder under steady state conditions.
The governing equations which used are continuity, momentum and
energy equations under an assumptions used Darcy law and
Boussinesq-s approximation which are transformed to dimensionless
equations. The finite difference approach is used to obtain all the
computational results using the MATLAB-7. The parameters affected
on the system are modified Rayleigh number (10 ≤Ra*≤ 1000), fin
length Hf (3, 7 and 11mm), radius ratio Rr (0.293, 0.365 and 0.435)
and the volume fraction(0 ≤ ¤ò ≤ 0 .35). It was found that the
average Nusselt number depends on (Ra*, Hf, Rr and φ). The results
show that, increasing of fin length decreases the heat transfer rate and
for low values of Ra*, decreasing Rr cause to decrease Nu while for
Ra*
greater than 100, decreasing Rr cause to increase Nu and adding
Cu nanoparticles with 0.35 volume fraction cause 27.9%
enhancement in heat transfer. A correlation for Nu in terms of Ra*,
Hf and φ, has been developed for inner hot cylinder.
Abstract: Samples of CoFe2-xCrxO4 where x varies from 0.0 to 0.5 were prepared by co-precipitation route. These samples were sintered at 750°C for 2 hours. These particles were characterized by X-ray diffraction (XRD) at room temperature. The FCC spinel structure was confirmed by XRD patterns of the samples. The crystallite sizes of these particles were calculated from the most intense peak by Scherrer formula. The crystallite sizes lie in the range of 37-60 nm. The lattice parameter was found decreasing upon substitution of Cr. DC electrical resistivity was measured as a function of temperature. The room temperature thermoelectric power was measured for the prepared samples. The magnitude of Seebeck coefficient depends on the composition and resistivity of the samples.
Abstract: The present paper discusses the selection of process
parameters for obtaining optimal nanocrystallites size in the CuOZrO2
catalyst. There are some parameters changing the inorganic
structure which have an influence on the role of hydrolysis and
condensation reaction. A statistical design test method is
implemented in order to optimize the experimental conditions of
CuO-ZrO2 nanoparticles preparation. This method is applied for the
experiments and L16 orthogonal array standard. The crystallites size
is considered as an index. This index will be used for the analysis in
the condition where the parameters vary. The effect of pH, H2O/
precursor molar ratio (R), time and temperature of calcination,
chelating agent and alcohol volume are particularity investigated
among all other parameters. In accordance with the results of
Taguchi, it is found that temperature has the greatest impact on the
particle size. The pH and H2O/ precursor molar ratio have low
influences as compared with temperature. The alcohol volume as
well as the time has almost no effect as compared with all other
parameters. Temperature also has an influence on the morphology
and amorphous structure of zirconia. The optimal conditions are
determined by using Taguchi method. The nanocatalyst is studied by
DTA-TG, XRD, EDS, SEM and TEM. The results of this research
indicate that it is possible to vary the structure, morphology and
properties of the sol-gel by controlling the above-mentioned
parameters.
Abstract: Magnesium alloys have gained increased attention in recent years in automotive, electronics, and medical industry. This because of magnesium alloys have better properties than aluminum alloys and steels in respects of their low density and high strength to weight ratio. However, the main problems of magnesium alloy welding are the crack formation and the appearance of porosity during the solidification. This paper proposes a unique technique to weld two thin sheets of AZ31B magnesium alloy using a paste containing Ag nanoparticles. The paste containing Ag nanoparticles of 5 nm in average diameter and an organic solvent was used to coat the surface of AZ31B thin sheet. The coated sheet was heated at 100 °C for 60 s to evaporate the solvent. The dried sheet was set as a lower AZ31B sheet on the jig, and then lap fillet welding was carried out by using a pulsed Nd:YAG laser in a closed box filled with argon gas. The characteristics of the microstructure and the corrosion behavior of the joints were analyzed by opticalmicroscopy (OM), energy dispersive spectrometry (EDS), electron probe micro-analyzer (EPMA), scanning electron microscopy (SEM), and immersion corrosion test. The experimental results show that the wrought AZ31B magnesium alloy can be joined successfully using Ag nanoparticles. Ag nanoparticles insert promote grain refinement, narrower the HAZ width and wider bond width compared to weld without and insert. Corrosion rate of welded AZ31B with Ag nanoparticles reduced up to 44 % compared to base metal. The improvement of corrosion resistance of welded AZ31B with Ag nanoparticles due to finer grains and large grain boundaries area which consist of high Al content. β-phase Mg17Al12 could serve as effective barrier and suppressed further propagation of corrosion. Furthermore, Ag distribution in fusion zone provide much more finer grains and may stabilize the magnesium solid solution making it less soluble or less anodic in aqueous
Abstract: Spherical shaped magnetite (Fe3O4) and Au@Fe3O4
nanoparticles were successfully synthesized from Fe electrodes
immersed in water with CTAB surfactant and HAuCl4 solution using
simple method-pulsed plasma in liquid, without the use of dopants or
special conditions for stabilization. Vibrating sample magnetometer
indicated ferromagnetic behavior of particles at room temperature with
coercivity and saturation magnetization of (Hc=105 Oe, Ms=6.83
emu/g) for Fe3O4 and (Hc=175, Ms=3.56emu/g) for Au@Fe3O4
nanoparticles. Structure and morphology of nanoparticles were
characterized by X-ray Diffraction analysis and HR-TEM
measurements. The cytotoxicity of nanoparticles was indicated using a
XTT assay to be very low (cell viability: 98-89% with Fe3O4 and
99-91% for Au@Fe3O4 NPs).
Abstract: The present contribution deals with the
thermophoretic deposition of nanoparticles over a rapidly rotating
permeable disk in the presence of partial slip, magnetic field, thermal
radiation, thermal-diffusion, and diffusion-thermo effects. The
governing nonlinear partial differential equations such as continuity,
momentum, energy and concentration are transformed into nonlinear
ordinary differential equations using similarity analysis, and the
solutions are obtained through the very efficient computer algebra
software MATLAB. Graphical results for non-dimensional
concentration and temperature profiles including thermophoretic
deposition velocity and Stanton number (thermophoretic deposition
flux) in tabular forms are presented for a range of values of the
parameters characterizing the flow field. It is observed that slip
mechanism, thermal-diffusion, diffusion-thermo, magnetic field and
radiation significantly control the thermophoretic particles deposition
rate. The obtained results may be useful to many industrial and
engineering applications.
Abstract: The systematic manipulations of shapes and sizes of
inorganic compounds greatly benefit the various application fields
including optics, magnetic, electronics, catalysis and medicine.
However shape control has been much more difficult to achieve.
Hence exploration of novel method for the preparation of differently
shaped nanoparticles is challenging research area. II-VI group of
semiconductor cadmium sulphide (CdS) nanostructure with different
morphologies (such as, acicular like, mesoporous, spherical shapes)
and of crystallite sizes vary from 11 to 16 nm were successfully
synthesized by chemical aqueous precipitation of Cd2+ ions with
homogeneously released S2- ions from decomposition of cadmium
sulphate (CdSO4) and thioacetamide (CH3CSNH2) by annealing at
different radiations (microwave, ultrasonic and sunlight) with matter
and systematic research has been done for various factors affecting
the controlled growth rate of CdS nanoparticles. The obtained
nanomaterials have been characterized by X-ray Diffraction (XRD),
Fourier Transform Infrared Spectroscopy (FTIR),
Thermogravometric (DSC-TGA) analysis and Scanning Electron
Microscopy (SEM). The result indicates that on increasing the
reaction time particle size increases but on increasing the molar ratios
grain size decreases.
Abstract: ZnS nanoparticles of different size have been
synthesized using a colloidal particles method. Zns nanoparticles
prepared with capping agent (mercaptoethanol) then were
characterized using X-ray diffraction (XRD) and UV-Vis
spectroscopy. The particle size of the nanoparticles calculated from
the XRD patterns has been found in the range 1.85-2.44nm.
Absorption spectra have been obtained using UV-Vis
spectrophotometer to find the optical band gap and the obtained
values have been founded to being range 3.83-4.59eV. It was also
found that energy band gap increase with the increase in molar
capping agent solution.
Abstract: n-CdO/p-Si heterojunction diode was fabricated using
sol-gel spin coating technique which is a low cost and easily scalable
method for preparing of semiconductor films. The structural and
morphological properties of CdO film were investigated. The X-ray
diffraction (XRD) spectra indicated that the film was of
polycrystalline nature. The scanning electron microscopy (SEM)
images indicate that the surface morphology CdO film consists of the
clusters formed with the coming together of the nanoparticles. The
electrical characterization of Au/n-CdO/p–Si/Al heterojunction diode
was investigated by current-voltage. The ideality factor of the diode
was found to be 3.02 for room temperature. The reverse current of
the diode strongly increased with illumination intensity of 100
mWcm-2 and the diode gave a maximum open circuit voltage Voc of
0.04 V and short-circuits current Isc of 9.92×10-9 A.
Abstract: spherical porous carbon particles with
controllable porosity with a mean size of 2.5m have been
prepared using a spray drying method with organic particle
colloidal template. As a precursor, a mixing solution of carbon
nanopowder and polystyrene (PS) particles as a template was
used. The result showed that the particles with a good porous
structure could be obtained. The pore size and shape (spherical)
were identical to the initial template, giving a potential way for
further developments. The control of particle porosity was also
possible and reported in this paper, in which this control could
be achieved by means of PS concentration.
Abstract: Antimicrobial resistant is becoming a major factor in
virtually all hospital acquired infection may soon untreatable is a
serious public health problem. These concerns have led to major
research effort to discover alternative strategies for the treatment of
bacterial infection. Nanobiotehnology is an upcoming and fast
developing field with potential application for human welfare. An
important area of nanotechnology for development of reliable and
environmental friendly process for synthesis of nanoscale particles
through biological systems In the present studies are reported on the
use of fungal strain Aspergillus species for the extracellular synthesis
of bionanoparticles from 1 mM silver nitrate (AgNO3) solution. The
report would be focused on the synthesis of metallic bionanoparticles
of silver using a reduction of aqueous Ag+ ion with the
culture supernatants of Microorganisms. The bio-reduction of the
Ag+ ions in the solution would be monitored in the aqueous
component and the spectrum of the solution would measure through
UV-visible spectrophotometer The bionanoscale particles were
further characterized by Atomic Force Microscopy (AFM), Fourier
Transform Infrared Spectroscopy (FTIR) and Thin layer
chromatography. The synthesized bionanoscale particle showed a
maximum absorption at 385 nm in the visible region. Atomic Force
Microscopy investigation of silver bionanoparticles identified that
they ranged in the size of 250 nm - 680 nm; the work analyzed the
antimicrobial efficacy of the silver bionanoparticles against various
multi drug resistant clinical isolates. The present Study would be
emphasizing on the applicability to synthesize the metallic
nanostructures and to understand the biochemical and molecular
mechanism of nanoparticles formation by the cell filtrate in order to
achieve better control over size and polydispersity of the
nanoparticles. This would help to develop nanomedicine against
various multi drug resistant human pathogens.
Abstract: Localized surface plasmon resonance (LSPR) is the
coherent oscillation of conductive electrons confined in noble
metallic nanoparticles excited by electromagnetic radiation, and
nanosphere lithography (NSL) is one of the cost-effective methods to
fabricate metal nanostructures for LSPR. NSL can be categorized
into two major groups: dispersed NSL and closely pack NSL. In
recent years, gold nanocrescents and gold nanoholes with vertical
sidewalls fabricated by dispersed NSL, and silver nanotriangles and
gold nanocaps on silica nanospheres fabricated by closely pack NSL,
have been reported for LSPR biosensing. This paper introduces
several novel gold nanostructures fabricated by NSL in LSPR
applications, including 3D nanostructures obtained by evaporating
gold obliquely on dispersed nanospheres, nanoholes with slant
sidewalls, and patchy nanoparticles on closely packed nanospheres,
all of which render satisfactory sensitivity for LSPR sensing. Since
the LSPR spectrum is very sensitive to the shape of the metal
nanostructures, formulas are derived and software is developed for
calculating the profiles of the obtainable metal nanostructures by
NSL, for different nanosphere masks with different fabrication
conditions. The simulated profiles coincide well with the profiles of
the fabricated gold nanostructures observed under scanning electron
microscope (SEM) and atomic force microscope (AFM), which
proves that the software is a useful tool for the process design of
different LSPR nanostructures.