Open Access Original Research Article

Quality Control Assessment of Diagnostic X-Ray Units in Zanzibar, Tanzania

Suleiman Ameir Suleiman, Salum Kombo Salum, Ebenezer Kimaro

Physical Science International Journal, Page 1-9
DOI: 10.9734/psij/2020/v24i1230228

Regular execution of quality control (QC) tests in medical diagnostic X-ray units is primarily important to provide high-quality images and proper diagnoses with least hazard. The performance criteria in diagnostic radiology in Zanzibar Islands, Tanzania were followed in accordance with the QC guidelines, and the values of the measured parameters were compared with the tolerance limits. The study was designed to perform QC tests on the diagnostic X-ray units in governmental and private hospitals. In this study six QC tests (beam alignment, beam collimation, kV reproducibility, half-value layer (HVL), mAs linearity and kV accuracy) were carried out by using beam alignment tool and Unfors non-invasive X-ray test device (Xi R/F&MAM detector). The measured parameters were conducted in two periods, from 2017 to 2018 (14 X-ray units were considered) and from 2019 to 2020 (16 X-ray units were considered). In both periods, the QC test results indicated that 100% of the X-ray units had acceptable HVL≥ 2.3 mm Al at 80 kVp. In the first period (2017−2018), the QC results showed that 78.57% and 85.71% had acceptable beam alignment (≤3% of the focus to image distance) and beam collimation (≤ ± 2 cm). Of the X-ray units evaluated, 85.71% had tolerable kV reproducibility of 5%, and 71.43% had mAs linearity within the tolerance limit of 10%, whereas 85.71% had acceptable kV accuracy within the tolerance limit of 5%. In the second period (2019−2020), the tolerance limits of X-ray units exceeded by 8.04% for kV reproducibility, 8.04% for kV accuracy, 16.07% for mAs linearity, 8.93% for beam alignment and 8.04% for beam collimation. The exceeded tolerance limits could be attributed to the new X-ray units which have full support of service agreements signed during the second period and increase of the compliances with the Tanzania Atomic Energy Act. No 7 of 2003 and its regulations. Results obtained highlight the need to regularly carry out comprehensive QC tests together with routine equipment maintenance.

Open Access Original Research Article

Re-interpretation of the Two-World Background of Special Relativity as Four-World Background

O. Akindele Adekugbe Joseph

Physical Science International Journal, Page 10-38
DOI: 10.9734/psij/2020/v24i1230229

The appropriate placements of the four-dimensional spacetimes of different universes make their coexistence possible, such that corresponding points in spacetimes within the universes are not separated in space or time. The corresponding points do not touch, because they are points in separate spacetimes. The different universes are described heuristically as existing in separate spacetime ‘compartments’. This new conception of many worlds (or universes) is therefore entitled compartment worlds (or universes) in this article. Compartment universes is a potential platform for many-world interpretations and uniform formulation of the natural laws. The two-world background of the special theory of relativity (SR) (involving two compartment universes), demonstrated elsewhere, is re-interpreted as four-world background (involving four compartment universes) in this article.

Open Access Original Research Article

A Study of Self-Organization in Small Systems with Simple Dynamics

William J. B. Oldham, James Rejcek

Physical Science International Journal, Page 39-59
DOI: 10.9734/psij/2020/v24i1230230

Self-organization in small systems of particles with simple dynamic laws has been simulated.  The purpose of this work is to investigate self-organization in small systems where we could follow individual particles.  The intention is to look for pattern formation as the system evolves.  For the two kinds of systems studied, the motion and the final system state for various dynamic iterations are presented.  In the first system design, two kinds of particles are simulated.  Like particles have a repulsive force, while unlike particles have an attractive force.  Initially, the particles are randomly distributed in a two dimensional square bounded region, and then allowed to dynamically interact for a number of iterations.  In experiment 1 the particles have different polarity.  Using the inverse square law force, modified at short distances, most cases resulted in equilibrium with the particles of opposite polarity paired up. Since this was a state of equilibrium no more movement occurred.  In the second experiment, there are two groups of particles initially separated by a boundary.  The particles on each side of the boundary are further divided into two groups referred to as strong or weak particles.  In this experiment the resulting patterns were clusters of particles. The forces among all of the particles can be varied to study the configurations that result from the dynamics.  The results of the experiments are presented in graphical format.  The main conclusion is that this model can be used to study small dynamic systems.

Open Access Original Research Article

Structural Optimization and the Study of the Electronic, Mechanical, Thermodynamic and Phonon Properties of Mg2sn from First Principle

I. S. Okunzuwa, E. Aigbekaen, Eddy, T. Philips Chidubem

Physical Science International Journal, Page 60-71
DOI: 10.9734/psij/2020/v24i1230232

First principles pseudopotential method based on density functional theory is used to investigate the Structural, Mechanical, Phonon, Thermodynamic and Electronic properties of Mg2Sn. The equilibrium properties including lattice constant, bulk modulus, pressure derivative cohesive energy, young modulus, shear modulus were determined. The results obtained were compared with available experimental and other available results. Mg2Sn was found to be brittle in nature with a non-metallic properties as shown by the value of the Cauchy pressure of -4.03. The Phonon dispersion curve of Mg2Sn was obtained utilizing the PBE-GGA exchange-correlation potential as employed in the Vienna Ab-Initio Simulation Package (VASP) computer code. The gap separating the acoustic and the optical branch of the curve was found to be about 50cm-1 at X-point. The thermodynamic properties of the material was investigated in the temperature of 0-800K. At room temperature, the calculated value of the specific heat capacity ( ) is 71.28J/mol which is in good agreement with experimental and other results. Mg2Sn was found to a narrow gap semiconductor with an indirect bandgap of magnitude of 0.175eV.