Iraqi Journal of Physics

A low-cost reverse flow plasma system powered by argon gas
pumping was built using homemade materials in this paper. The
length of the resulting arc change was directly proportional to the
flow rate, while using the thermal camera to examine the thermal
intensity distribution and demonstrating that it is concentrated in the
centre, away from the walls at various flow rates, the resulting arc's
spectra were also measured. The results show that as the gas flow
rate increased, so did the ambient temperature. The results show that
the medium containing the arc has a maximum temperature of 34.1
˚C at a flow rate of 14 L/min and a minimum temperature of 22.6 ˚C
at a flow rate of 6 L/min.

The biggest problem of structural materials for fusion reactor is
the damage caused by the fusion product neutrons to the structural
material. If this problem is overcomed, an important milestone will
be left behind in fusion energy. One of the important problems of the
structural material is that nuclei forming the structural material
interacting with fusion neutrons are transmuted to stable or
radioactive nuclei via (n, x) (x; alpha, proton, gamma etc.) reactions.
In particular, the concentration of helium gas in the structural
material increases through deuteron- tritium (D-T) and (n, α)
reactions, and this increase significantly changes the microstructure
and the properties of the structural materials. Therefore, in this study,
the effects of the different nuclear level density models on the
excitation functions of the (n, α) reactions on 46-50Ti isotopes, an
attractive candidate for the structural material for fusion reactors,
have been investigated for the first time. Also, the differential crosssections with respect to alpha energy for the emission of alpha
particles of the 46-50Ti (n, xα) reactions have been investigated at
14.1 MeV incident neutron energy. The calculations are performed
using the two-component exciton model in the TALYS 1.9 code, and
the results are compared with available experimental data. The
results of this study will contribute to nuclear database as required
for improving, design and operations of the important facilities as
ITER (International Thermonuclear Experimental Reactor), DEMO
(The demonstration power plant) and ENS (European Nuclear
Society).

The gas sensing properties of undoped Co3O4 and doped with Y2O3
nanostructures were investigated. The films were synthesized using the
hydrothermal method on a seeded layer. The XRD, SEM analysis and gas
sensing properties were investigated for the prepared thin films. XRD
analysis showed that all films were polycrystalline, of a cubic structure
with crystallite size of (12.6) nm for cobalt oxide and (12.3) nm for the
Co3O4:6% Y2O3. The SEM analysis of thin films indicated that all films
undoped Co3O4 and doped possessed a nanosphere-like structure.
The sensitivity, response time and recovery time to H2S reducing and
NO2 oxidizing gases were tested at different operating temperatures. The
resistance changed with exposure to the test gas. The results revealed that
the Co3O4:6%Y2O3 possessed the highest sensitivity around 90% (at room
temperature) and 62.5% (at 150 oC) when exposed to the reducing gas H2S
and oxidizing gas NO2, respectively with 0.8sec for both recovery and
response times.

In this work, the linear properties of Vitamin D3-5000IU soft
gel were investigated by measuring its absorption and fluorescence
spectra. It was observed that there was a shift towards longer
wavelength within limits (75 nm), with quantitative efficiency equal
to (33.58%). The values of absorbance were used to calculate the
extinction coefficient, optical refractive index, optical conductivity
and optical dielectric constant values.
The non-linear properties of Vitamin D3-5000IU soft gel was
also studied using the Z-Scan technique by using Neodymium-doped
Yttrium Garnet (Nd: YAG) continuous laser (CW) emitting in
(532 nm) wavelength, by utilize open aperture to measure nonlinear
absorption coefficient and close aperture (diameter 1.5mm) to
measure nonlinear refractive index. The sample behaves as twophoton absorption, and the nonlinear refractive index was positive.

In this study, polymeric coating was developed by incorporating
nano graphene in the polymer blend with applications to oil storage
tanks. The oil storage tanks samples were brought from the oil Pipeline
Company / Doura refinery in Baghdad. The coating polymer was
formed with a blend (epoxy resin and repcoat ZR). The proportion of
mixing the mixture was 3:1:1 epoxy resin 21.06 gm: repcoat ZR 10.53
gm: hardener 10.53 gm. The blend/graphene was prepared using in
stui-polymerization method with different weight percentage 1, 3, 5,
and 7 wt % added to blend. The resulting solution was put in a glass
tube on a magnetic stirrer for one hour at a temperature of 40 °C. The
result of contact angle and water absorption the best ratio of 3wt %
(73.46). The current work confirms that the thermal stability of the
nanocomposites increases gradually with increasing the percentage of
Gr compared to the blend without adding Gr nano and this is due to
the thermal resistance of the Gr nano.

A chemical optical fiber sensor based on surface plasmon
resonance (SPR) was developed and implemented using multimode
plastic optical fiber. The sensor is used to detect and measure the
refractive index and concentration of various chemical materials
(Urea, Ammonia, Formaldehyde and Sulfuric acid) as well as to
evaluate the performance parameters such as sensitivity, signal to
noise ratio, resolution and figure of merit. It was noticed that the
value of the sensitivity of the optical fiber-based SPR sensor, with
60nm and 10 mm long, Aluminum(Al) and Gold (Au) metals film
exposed sensing region, was 4.4 μm, while the SNR was 0.20, figure
of merit was 20 and resolution 0.00045. In this work a multimode
plastic optical fiber with a core diameter of 980 μm, fluorinated
polymer cladding of 20 μm and a numerical aperture of 0.51 was
used.

The two-neutron halo-nuclei (17B, 11Li, 8He) was investigated
using a two-body nucleon density distribution (2BNDD) with two
frequency shell model (TFSM). The structure of valence two-neutron
of 17B nucleus in a pure (1d5/2) state and in a pure (1p1/2) state for
11L and 8He nuclei. For our tested nucleus, an efficient (2BNDD's)
operator for point nucleon system folded with two-body correlation
operator's functions was used to investigate nuclear matter density
distributions, root-mean square (rms) radii, and elastic electron
scattering form factors. In the nucleon-nucleon forces the correlation
took account of the effect for the strong tensor force (TC's). The
wave functions of single particle harmonic oscillator are used with
two different oscillator size parameters βc and βv, where the former
is for the core (inner) orbits and the latter is for the valence (halo)
orbits. The measured matter density distributions of these nuclei
clearly showed long tail results. To investigate elastic electron
scattering form factors the plane wave born approximation (PWBA)
with two body nucleon density distribution (2BNDD's) was use.

The present work shows a theoretical results that have been
used the functional Hybrid of three parameters Lee-Yang-Parr
(B3LYP) of the quantum mechanical approach for density functional
theory with (Spanish Initiative for Electronic Simulations with
Thousands of Atoms) SIESTA code. All calculations were carried
out employing the used method at the Gaussian 09 package of
programs. It was reported the main point for research on dominance
of the bandgap of elongated pi-conjugated molecules by using
different chemical groups replacing hydrogen atom in the most
molecules that used in this work. The side groups creates another
factor that controls the value of the band gap. The dihedral angle
between the two phenyl rings plays more important role in
controlling the band gap in these molecules.

Using photo electrochemical etching technique, porous silicon
(PS) layer was prepared on n-type silicon wafers to generate porous
silicon for n-type with an orientation of (111). X-ray diffraction
pattern revealed differences between peaks where the high of the
peaks and intensity decreased with increasing etching time. The
largest crystal size was (30 nm) and the lowest crystal size was
(28.6 nm). The atomic force microscopy and field emission scanning
electron microscopy were used to study the morphology of porous
silicon layer. As the etching time was increased, AFM measurements
showed that (RMS), roughness and grain size decreased. FESEM
showed a homogeneous pattern and verified the formation of
uniform porous silicon.

In this work, wide band range photo detector operating in UV,
Visible and IR was fabricated using carbon nanotubes (MWCNTs,
SWCNTs) decorated with silver nanoparticles (Ag NPs). Silicon was
used as a substrate to deposited CNTs/Ag NPs by the drop casting
technique. Polyamide nylon polymer was used to coat CNTs/Ag NPs
to enhance the photo-response of the detector. The electro-exploding
wire technology was used to synthesize Ag NPs. Good dispersion of
silver NPs achieved by a simple chemistry process on the surface of
CNTs. The optical, structure and electrical characteristic of CNTs
decorated with Ag NPs were characterized by X-Ray diffraction and
Field Emission Scanning Electron Microscopy. X-ray diffraction
patterns of Ag NPs exhibited 2θ values (38.1°,44.3°) corresponding
to the Ag nanocrystal, while the XRD pattern of MWCNTs and
SWCNTs /Ag NPs peaks appeared at 2θ = 26.2° corresponding to the
(002) and at 2theta=44° which corresponds with miller indices (100)
for CNTs and (200) for Ag NPs. The optical properties measured by
UV-Vis. Spectroscopy. Broad and strong surface plasmon resonance
(SPR) peak was detected at 420 nm, for Ag NPs. The absorption of
CNTs/Ag NPs increased significantly from UV to near IR region
(300-1000 nm). Ag NPs decorated CNTs without any impurities,
according to field mission scanning electron microscopy
examination, with typical particle sizes of (50-80nm) for Ag-NPs,
44nm for MWCNTs/Ag-NPs, and 30nm for SWCNTs/Ag NPs. ֹThe
I-V characteristics at forward bias voltage (0.5-10) volt were studied.
The figure of merits (responsivity, photocurrent gain, NEP and
detectivity) after coating with polymer of the detector were measured
in the dark and after illumination with UV LED (365 nm), Tungsten
lamp (500-800 nm) and Laser diode (808 nm).