Abstract: Microbial fuel cells (MFCs) represent a promising
technology for simultaneous bioelectricity generation and wastewater
treatment. Catalysts are significant portions of the cost of microbial
fuel cell cathodes. Many materials have been tested as aqueous
cathodes, but air-cathodes are needed to avoid energy demands for
water aeration. The sluggish oxygen reduction reaction (ORR) rate at
air cathode necessitates efficient electrocatalyst such as carbon
supported platinum catalyst (Pt/C) which is very costly. Manganese
oxide (MnO2) was a representative metal oxide which has been
studied as a promising alternative electrocatalyst for ORR and has
been tested in air-cathode MFCs. However the single MnO2 has poor
electric conductivity and low stability. In the present work, the MnO2
catalyst has been modified by doping Pt nanoparticle. The goal of the
work was to improve the performance of the MFC with minimum Pt
loading. MnO2 and Pt nanoparticles were prepared by hydrothermal
and sol gel methods, respectively. Wet impregnation method was
used to synthesize Pt/MnO2 catalyst. The catalysts were further used
as cathode catalysts in air-cathode cubic MFCs, in which anaerobic
sludge was inoculated as biocatalysts and palm oil mill effluent
(POME) was used as the substrate in the anode chamber. The asprepared
Pt/MnO2 was characterized comprehensively through field
emission scanning electron microscope (FESEM), X-Ray diffraction
(XRD), X-ray photoelectron spectroscopy (XPS), and cyclic
voltammetry (CV) where its surface morphology, crystallinity,
oxidation state and electrochemical activity were examined,
respectively. XPS revealed Mn (IV) oxidation state and Pt (0)
nanoparticle metal, indicating the presence of MnO2 and Pt.
Morphology of Pt/MnO2 observed from FESEM shows that the
doping of Pt did not cause change in needle-like shape of MnO2
which provides large contacting surface area. The electrochemical
active area of the Pt/MnO2 catalysts has been increased from 276 to
617 m2/g with the increase in Pt loading from 0.2 to 0.8 wt%. The
CV results in O2 saturated neutral Na2SO4 solution showed that
MnO2 and Pt/MnO2 catalysts could catalyze ORR with different
catalytic activities. MFC with Pt/MnO2 (0.4 wt% Pt) as air cathode
catalyst generates a maximum power density of 165 mW/m3, which
is higher than that of MFC with MnO2 catalyst (95 mW/m3). The
open circuit voltage (OCV) of the MFC operated with MnO2 cathode
gradually decreased during 14 days of operation, whereas the MFC
with Pt/MnO2 cathode remained almost constant throughout the
operation suggesting the higher stability of the Pt/MnO2 catalyst.
Therefore, Pt/MnO2 with 0.4 wt% Pt successfully demonstrated as an
efficient and low cost electrocatalyst for ORR in air cathode MFC with higher electrochemical activity, stability and hence enhanced
performance.
Abstract: A new method for determining the distribution of
birefringence and linear dichroism in optical polymer materials is
presented. The method is based on the use of polarizationholographic
diffraction grating that forms an orthogonal circular basis
in the process of diffraction of probing laser beam on the grating. The
intensities ratio of the orders of diffraction on this grating enables the
value of birefringence and linear dichroism in the sample to be
determined. The distribution of birefringence in the sample is
determined by scanning with a circularly polarized beam with a
wavelength far from the absorption band of the material. If the
scanning is carried out by probing beam with the wavelength near to
a maximum of the absorption band of the chromophore then the
distribution of linear dichroism can be determined. An appropriate
theoretical model of this method is presented. A laboratory setup was
created for the proposed method. An optical scheme of the laboratory
setup is presented. The results of measurement in polymer films with
two-dimensional gradient distribution of birefringence and linear
dichroism are discussed.
Abstract: We study the anomalous WWγ and WWZ couplings by
calculating total cross sections of two processes at the LHeC with
electron beam energy Ee=140 GeV and the proton beam energy Ep=7
TeV, and at the FCC-ep collider with the polarized electron beam
energy Ee=80 GeV and the proton beam energy Ep=50 TeV. At the
LHeC with electron beam polarization, we obtain the results for the
difference of upper and lower bounds as (0.975, 0.118) and (0.285,
0.009) for the anomalous (Δκγ, λγ) and (Δκz, λz) couplings,
respectively. As for FCC-ep collider, these bounds are obtained as
(1.101, 0.065) and (0.320, 0.002) at an integrated luminosity of
Lint=100 fb^-1.
Abstract: Corrosion inhibitors are widely used in concrete
industry to reduce the corrosion rate of steel rebar which is present in
contact with aggressive environments. The present work aims to
using Zamzam water from well located within the Masjid al-Haram
in Mecca, Saudi Arabia 20 m (66 ft) east of the Kaaba, the holiest
place in Islam as corrosion inhibitor for steel in rain water and
simulated acid rain. The effect of Zamzam water was investigated by
electrochemical impedance spectroscopy (EIS) and Potentiodynamic
polarization techniques in Department of Civil Engineering - IUT
Saint-Nazaire, Nantes University, France. Zamzam water is
considered to be one of the most important steel corrosion inhibitor
which is frequently used in different industrial applications. Results
showed that zamzam water gave a very good inhibition for steel
corrosion in rain water and simulated acid rain.
Abstract: We have experimentally demonstrated bright-dark
pulses in a nonlinear polarization rotation (NPR) based mode-locked
Erbium-doped fiber laser (EDFL) with a long cavity configuration.
Bright–dark pulses could be achieved when the laser works in the
passively mode-locking regime and the net group velocity dispersion
is quite anomalous. The EDFL starts to generate a bright pulse train
with degenerated dark pulse at the mode-locking threshold pump
power of 35.09 mW by manipulating the polarization states of the
laser oscillation modes using a polarization controller (PC). A split
bright–dark pulse is generated when further increasing the pump
power up to 37.95 mW. Stable bright pulses with no obvious
evidence of a dark pulse can also be generated when further adjusting
PC and increasing the pump power up to 52.19 mW. At higher pump
power of 54.96 mW, a new form of bright-dark pulse emission was
successfully identified with the repetition rate of 29 kHz. The bright
and dark pulses have a duration of 795.5 ns and 640 ns, respectively.
Abstract: A circularly polarized fractal boundary microstrip
antenna is presented. The sides of a square patch along x- axis, yaxis
are replaced with Minkowski and Koch curves correspondingly.
By using the fractal curves as edges, asymmetry in the structure is
created to excite two orthogonal modes for circular polarization (CP)
operation. The indentation factors of the fractal curves are optimized
for pure CP. The simulated results of the novel polyfractal antenna
are demonstrated.
Abstract: A simple multi-wavelength passively Q-switched
Erbium-doped fiber laser (EDFL) is demonstrated using low cost
multi-walled carbon nanotubes (MWCNTs) based saturable absorber
(SA), which is prepared using polyvinyl alcohol (PVA) as a host
polymer. The multi-wavelength operation is achieved based on
nonlinear polarization rotation (NPR) effect by incorporating 50 m
long photonic crystal fiber (PCF) in the ring cavity. The EDFL
produces a stable multi-wavelength comb spectrum for more than 14
lines with a fixed spacing of 0.48 nm. The laser also demonstrates a
stable pulse train with the repetition rate increases from 14.9 kHz to
25.4 kHz as the pump power increases from the threshold power of
69.0 mW to the maximum pump power of 133.8 mW. The minimum
pulse width of 4.4 μs was obtained at the maximum pump power of
133.8 mW while the highest energy of 0.74 nJ was obtained at pump
power of 69.0 mW.
Abstract: Al-Si-Mg-Ni(-Cu) alloys are widely used in the automotive industry. They have the advantage of low weight associated with low coefficient of thermal expansion and excellent mechanical properties – mainly at high temperatures. The corrosion resistance of these alloys in coastal area, particularly sea water, however is not yet known. In this investigation, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization have been used to evaluate the corrosion resistance of Al-6Si-0.5Mg-2Ni (-2Cu) alloys in simulated sea water environments. The potentiodynamic polarization curves reveal that 2 wt% Cu content alloy (Alloy-2) is more prone to corrosion than the Cu free alloy (Alloy-1). But the EIS test results showed that corrosion resistance or charge transfer resistance (Rct) increases with the addition of Cu. Due to addition of Cu and thermal treatment, the magnitude of open circuit potential (OCP), corrosion potential (Ecorr) and pitting corrosion potential (Epit) of Al-6Si-0.5Mg-2Ni alloy in NaCl solution were shifted to the more noble direction.
Abstract: This research studies the electroplating of zinc coating
in the zinc chloride bath mixed with supercritical CO2. The sodium
fluoride (NaF) was used as the bath additive to change the structure
and property of the coating, and therefore the roughness and corrosion
resistance of the zinc coating was investigated. The surface
characterization was performed using optical microscope (OM), X-ray
diffractometer (XRD), and α-step profilometer. Moreover, the
potentiodynamic polarization measurement in 3% NaCl solution was
employed in the corrosion resistance evaluation. Because of the
emulsification of the electrolyte mixed in Sc-CO2, the electroplated
zinc produced the coating with smoother surface, smaller grain, better
throwing power and higher corrosion resistance. The main role played
by the NaF was to reduce the coating’s roughness and grain size. In
other words, the CO2 mixed with the electrolyte under the supercritical
condition performed the similar function as brighter and leveler in zinc
electroplating to enhance the throwing power and corrosion resistance
of the coating.
Abstract: We offer a new technique for research of stability of current sheaths in space plasma taking into account the effect of polarization. At the beginning, the found perturbation of the distribution function is used for calculation of the dielectric permeability tensor, which simulates inhomogeneous medium of a current sheath. Further, we in the usual manner solve the system of Maxwell's equations closed with the material equation. The amplitudes of Fourier perturbations are considered to be exponentially decaying through the current sheath thickness. The dispersion equation follows from the nontrivial solution requirement for perturbations of the electromagnetic field. The resulting dispersion equation allows one to study the temporal and spatial characteristics of instability modes of the current sheath (within the limits of the proposed model) over a wide frequency range, including low frequencies.
Abstract: This paper proposes the development and design of
double layer metamaterials based on electromagnetic band gap
(EBG) rods as a superstrate of a resonator antenna to enhance
required antenna characteristics for the mobile base station. The
metallic rod type metamaterial can partially reflect wave of a primary
radiator. The antenna was designed and analyzed by a simulation
result from CST Microwave Studio and designed technique could be
confirmed by a measurement results from prototype antenna that
agree with simulation results. The results indicate that the antenna
can also generate a dual polarization by using a 45˚ oriented curved
strip dipole located at the center of the reflector plane with double
layer superstrate. It can be used to simplify the feed system of an
antenna. The proposed antenna has a bandwidth covering the
frequency range of 1920 – 2200 MHz, the gain of the antenna
increases up to 14.06 dBi. In addition, an interesting sectoral 60˚
pattern is presented in horizontal plane.
Abstract: In this study, a plasma electrolytic oxidation (PEO) process was used to form titanium-aluminum oxide coating on aluminized steel. The present work was mainly to study the effects of treatment time of PEO process on properties of the titanium coating. A potentiodynamic polarization corrosion test was employed to investigate the corrosion resistance of the coating. The friction coefficient and wear resistance of the coating were studied by using pin-on-disc test. The thermal transfer behaviors of uncoated and PEO-coated aluminized steels were also studied. It could be seen that treatment time of PEO process significantly influenced the properties of the titanium oxide coating. Samples with a longer treatment time had a better performance for corrosion and wear protection. This paper demonstrated different treatment time could alter the surface behavior of the coating material.
Abstract: Schiff base (E)-2-methyl-N-(tetrazolo[1,5-a]quinolin-4-ylmethylene)aniline (QMA) was synthesized, and its inhibitive effect for mild steel in 1N HCl solution was investigated by weight loss measurement and electrochemical tests. From the weight loss measurements and electrochemical tests, it was observed that the inhibition efficiency increases with the increase in the Schiff base concentration and reaches a maximum at the optimum concentration. This is further confirmed by the decrease in corrosion rate. It is found that the system follows Langmuir adsorption isotherm.
Abstract: Molasses is one of the most important by-products in sugar industry, which contains a large amount of sucrose. The routine way to separate the sucrose from molasses is using steffen method. Whereas this method is very usual in sugar factories, the aim of this research is optimization of this method. Mentioned optimization depends to three factors of reactor alkality, reactor temperature and diluted molasses brix. Accordingly, three different stages must be done:
Construction of a pilot plant similar to actual steffen system in sugar factories
Experimenting using the pilot plant
Laboratory analysis
These experiences included 27 treatments in three replications. In each replication, brix, polarization and purity characters in Saccharate syrup and hot and cold waste were measured. The results showed that diluted molasses brix, reactor alkality and reactor temperature had many significant effects on Saccharate purity and efficiency of molasses desugarization. This research was performed in "randomize complete design" form & was analyzed with "duncan multiple range test". The significant difference in the level of α = 5% is observed between the treatments. The results indicated that the optimal conditions for molasses desugarization by steffen method are: diluted molasses brix= 10, reactor alkality= 10 and reactor temperature=8˚C.
Abstract: Heterogeneous repolarization causes dispersion of the T-wave and has been linked to arrhythmogenesis. Such heterogeneities appear due to differential expression of ionic currents in different regions of the heart, both in healthy and diseased animals and humans. Mice are important animals for the study of heart diseases because of the ability to create transgenic animals. We used our previously reported model of mouse ventricular myocytes to develop 2D mouse ventricular tissue model consisting of 14,000 cells (apical or septal ventricular myocytes) and to study the stability of action potential propagation and Ca2+ dynamics. The 2D tissue model was implemented as a FORTRAN program code for highperformance multiprocessor computers that runs on 36 processors. Our tissue model is able to simulate heterogeneities not only in action potential repolarization, but also heterogeneities in intracellular Ca2+ transients. The multicellular model reproduced experimentally observed velocities of action potential propagation and demonstrated the importance of incorporation of realistic Ca2+ dynamics for action potential propagation. The simulations show that relatively sharp gradients of repolarization are predicted to exist in 2D mouse tissue models, and they are primarily determined by the cellular properties of ventricular myocytes. Abrupt local gradients of channel expression can cause alternans at longer pacing basic cycle lengths than gradual changes, and development of alternans depends on the site of stimulation.
Abstract: In this paper, a new design technique for enhancing
bandwidth that improves the performance of a conventional
microstrip patch antenna is proposed. This paper presents a novel
wideband probe fed inverted slotted microstrip patch antenna. The
design adopts contemporary techniques; coaxial probe feeding,
inverted patch structure and slotted patch. The composite effect of
integrating these techniques and by introducing the proposed patch,
offer a low profile, broadband, high gain, and low cross-polarization
level. The results for the VSWR, gain and co-and cross-polarization
patterns are presented. The antenna operating the band of 1.80-2.36
GHz shows an impedance bandwidth (2:1 VSWR) of 27% and a gain
of 10.18 dBi with a gain variation of 1.12 dBi. Good radiation
characteristics, including a cross-polarization level in xz-plane less
than -42 dB, have been obtained.
Abstract: In this paper, an adaptive polarized Multiple-Input
Multiple-Output (MIMO) Multicarrier Spread Spectrum Code Division Multiple Access (MC-SS-CDMA) system is designed for downlink mobile communications. The proposed system will be
examined in Frequency Division Duplex (FDD) mode for both macro urban and suburban environments. For the same transmission
bandwidth, a performance comparison between both nonoverlapped and orthogonal Frequency Division Multiplexing (FDM) schemes will be presented. Also, the proposed system will be compared with
both the closed loop vertical MIMO MC-SS-CDMA system and the
synchronous vertical STBC-MIMO MC-SS-CDMA system. As will
be shown, the proposed system introduces a significant performance
gain as well as reducing the spatial dimensions of the MIMO system
and simplifying the receiver implementation. The effect of the
polarization diversity characteristics on the BER performance will be
discussed. Also, the impact of excluding the cross-polarization MCSS-
CDMA blocks in the base station will be investigated. In addition,
the system performance will be evaluated under different Feedback
Information (FBI) rates for slowly-varying channels. Finally, a
performance comparison for vehicular and pedestrian environments
will be presented
Abstract: The angular distribution of Compton scattering of two
quanta originating in the annihilation of a positron with an electron
is investigated as a quantum key distribution (QKD) mechanism in
the gamma spectral range. The geometry of coincident Compton
scattering is observed on the two sides as a way to obtain partially
correlated readings on the quantum channel. We derive the noise
probability density function of a conceptually equivalent prepare
and measure quantum channel in order to evaluate the limits of the
concept in terms of the device secrecy capacity and estimate it at
roughly 1.9 bits per 1 000 annihilation events. The high error rate
is well above the tolerable error rates of the common reconciliation
protocols; therefore, the proposed key agreement protocol by public
discussion requires key reconciliation using classical error-correcting
codes. We constructed a prototype device based on the readily
available monolithic detectors in the least complex setup.
Abstract: In this research paper, a slotted coaxial line fed cross
dipole excitation structure for short backfire antenna is proposed and
developed to achieve reconfigurable circular polarization. The cross
dipole, which is fed by the slotted coaxial line, consists of two
orthogonal dipoles. The dipoles are mounted on the outer conductor
of the coaxial line. A unique technique is developed to generate
reconfigurable circular polarization using cross dipole configuration.
The sub-reflector is supported by the feed line, thus requiring no
extra support. The antenna is developed on elliptical ground plane
with dielectric rim making antenna compact. It is demonstrated that
cross dipole excited short backfire antenna can achieve voltage
standing wave ratio (VSWR) bandwidth of 14.28% for 2:1 VSWR,
axial ratio of 0.2 dB with axial ratio (≤ 3dB) bandwidth of 2.14% and
a gain of more than 12 dBi. The experimental results for the designed
antenna structure are in close agreement with computer simulations.
Abstract: In this paper, the optical generation of three bands of
continuously tunable millimeter-wave signals using an optical phase
modulator (OPM) and a polarization state rotation filter (PSRF) as an
optical notch filter is analyzed. The effect of the chromatic dispersion
on millimeter-wave signals is presented.