The wear behavior of alumina particulate reinforced A332 aluminium alloy composites produced by a stir casting process technique were investigated. A pin-on-disc type apparatus was employed for determining the sliding wear rate in composite samples at different grain size (1 µm, 12µm, 50 nm) and different weight percentage (0.05-0.1-0.5-1) wt% of alumina respectively. Mechanical properties characterization which strongly depends on microstructure properties of reinforcement revealed that the presence of ( nano , micro) alumina particulates lead to simultaneous increase in hardness, ultimate tensile stress (UTS), wear resistances. The results revealed that UTS, Hardness, Wear resistances increases with the increase in the percentage of reinforcement of Al2O3 when compared to the base alloy A332. The wear rates of the composites were considerably less than that of the aluminum alloy at all applied loads with increasing percentage of reinforcement when compared to the base alloy A332.
Improve Wear Resistance on Al 332 Alloy Matrix- Micro -Nano Al2O3 Particles Reinforced Composite
Aluminium matrix composites
wear resistance
Micro -Nano Al2O3 particles
Publication Date
Mon Feb 25 2019
Journal Name
Iraqi Journal Of Physics
Comparison study of CC and CH vibration frequencies and eelectronic properties for mono, Di, Tri, and tetra-rings layer of arm chair (SWCNTs)
SWCNT single wall carbon nano tube
G03 aprogram for calculation
: Out of plane of the molecule
: In- plane of the molecule.
Semi-empirical methods were applied for calculating the vibration frequencies and IR absorption intensities for normal coordinates of the {mono (C56H28), di (C84H28), tri (C112H28) and tetra (C140H28)} -rings layer for (7,7) armchair single wall carbon nanotube at their equilibrium geometries which were all found to have D7d symmetry point group.
Assignment of the modes of vibration (3N-6) was done depending on the pictures of their modes by applying (Gaussian 03) program. Comparison of the vibration frequencies of (mono, di, tri and tetra) rings layer which are active in IR, and inactive in Ramman spectra. For C-H stretching vibrat
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Publication Date
Fri Mar 01 2019
Journal Name
Applied Acoustics
Theoretical model of absorption coefficient of an inhomogeneous MPP absorber with multi-cavity depths
Micro-perforated panel (MPP) absorber has been known as an alternative absorber to classical porous material given its facile installation
long durability
environmental friendliness and attractive appearance. Extensive studies of MPP absorber proposing the improvement of its absorption frequency bandwidth have been published. This study presents a MPP absorber introduced with inhomogeneous perforations and with multi-cavity depths. The MPP is divided into two sub-area
where each area has different hole diameter
perforation ratio and a separated backed cavity depth. The acoustic impedance is modelled using electrical equivalent circuit and the absorption coefficient is calculated under normal-incidence of sound. It is found that the inhomogeneous MPP can have good bandwidth of absorption by designing the sub-MPP of smaller perforation ratio with large hole diameter and the one having the larger perforation ratio with smaller hole diameter. The absorption bandwidth can be conveniently controlled by adjusting the cavity depth of each sub-MPP. The results from the experimental work show good agreement with the theoretical model.
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Publication Date
Fri Aug 01 2025
Journal Name
Microbial Pathogenesis
Antibacterial and therapeutic effects of vancomycin-resistant Staphylococcus aureus bacteriocin (VRSAcin) in the treatment of VRSA skin infection in mice
Vancomycin Staphylococcus aureus (VRSA) is a strain of S. aureus that is considered the main cause of bacterial
skin and soft tissue infections. It has acquired resistance to vancomycin and represents a therapeutic challenge.
The current study aimed to compare the possible therapeutic effects of VRSA bacteriocin (VRSAcin) on the
treatment of skin infection in mice with those of an antibiotic (linezolid). The results showed that of the fifty
swabs obtained from human skin wounds. One isolate was selected for VRSAcin extraction depending on its
antibiotic resistance using an antibiotic susceptibility test.An agar well diffusion test was used to determine
bacteriocin’s antibacterial activity
as well as its a minimum inhibitory concentration
minimum bactericidal
concentration
and antibiofilm efficiency against gram-positive and gram-negative bacteria that were resistant to
many medicines. The freshly developed antibacterial substance VRSAcin shows promise. Bacteriocin from VRSA
was extracted and studied the optimal conditions for the Production following Purification of bacteriocin by
ammonium sulfate precipitation followed by cation-exchange chromatography. The molecular weight of
bacteriocin about (29 kDa) were determined by Sodium Dodecyl Sulfate-polyacrylamide gel electrophoresis
(SDS-PAGE). The typical conditions for the production of VRSAcin include a pH of 7 and a temperature of 37 ◦C
for 48 h. In mice
VRSA-contaminated wounds revealed severe tissue distraction and inflammation that extended
to the hypodermis
while VRSA-treated skin showed mild changes and localized lesions to the epidermis and
upper dermis. The skin of linezolid ointment-treated mice showed moderate to severe changes. In conclusion
VRSA strain infections in human burned skin were more common than expected. In vivo studies in mice indicated
that wounded skin infected with VRSA can be treated with VRSAcin as an antibacterial agent that promotes
healing processes with obvious superiority to linezolid ointment. As a result
the VRSA develops bacteriocins that
are appropriate for regulating AMR
Gram-positive and Gram-negative bacteria
and may be useful in wound
dressings.
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