Open Access Short communication

Origin and Early Evolution of Terrestrial Planet Atmospheres and Oceans

Lin-gun Liu

Physical Science International Journal, Page 1-8
DOI: 10.9734/PSIJ/2018/45815

Planet atmospheric compositions are determined by the availability of a gas species, its molecular weight and the mass (or gravity force) of a planet.  Both Mercury and the Moon are not massive enough to hold any gas species to form an atmosphere.  The observed atmospheric compositions of all other terrestrial planets (Venus, Earth and Mars) are consistent with the calculated lower bounds of the critical mass (CM) for various atmospheric gas species.  The proto-atmospheres of Venus, Earth and Mars during accretion should be composed primarily of CO2.  The Martian mass is significantly smaller than the lower bound of CM for gaseous H2O. Thus, Mars is not capable of retaining H2O in its atmosphere.  In terms of today’s atmospheric compositions, the Earth appears to be the only “abnormal” planet in our Solar System.  This may suggest that the fate of the Earth might be unique among the terrestrial planets by the fact that the Earth has an over-massive Moon.  The capture of the Moon by a giant impact process might produce Earth’s indigenous hot supercritical H2O-CO2 ocean that quickly reacted with feldspar, the most abundant surface mineral, and eventually removed all CO2 from Earth’s proto-atmosphere.

Open Access Original Research Article

Evaluation of Essential Elements and Heavy Metals in Sardine Fish from Kivukoni, Kunduchi and Bagamoyo Fish Markets in Tanzania

Yusuf Ismail Koleleni, Prosper August Mosha

Physical Science International Journal, Page 1-16
DOI: 10.9734/PSIJ/2018/45156

This study has assessed the concentrations of the essential elements Ca, Cu, Fe, Se and Zn as well as the toxic heavy metals Al, As, Cd, Cr, Ni and Pb in samples of sardine fish collected from Kivukoni, Kunduchi and Bagamoyo fish markets. The collected fish samples were oven dried, grinded to fine powder and compressed to pellets. The pellets obtained were analysed for both essential elements and toxic heavy metals using Energy Dispersive X- rays Fluorescence Spectroscopy (EDXRF). The mean concentrations of the analysed elements were compared to the maximum tolerable levels (MTLs) set by international organisations. The mean concentrations of Ca, Se, Zn, As, Cr, and Cd were higher than their MTLs while, the mean concentrations of Cu and Ni were lower than their MTLs for samples from all fish markets. The mean concentrations of Al and Fe were higher than their MTLs for samples from Kunduchi and Bagamoyo fish markets. The mean concentrations of Pb were below the detection limit (0.50) µg/g for the spectrometer used in this study. The MTLs for Ca, Fe, Cu, Se, Zn, Al, Cr, Ni, As, and Cd were 130,000 ; 200 ; 30 ; 40 ; 0.75 ; 100 ; 0.15 ; 2.00 ; 0.50 ; 0.50 ; and 2.00 µg/g respectively, according to FAO/WHO 2002, WHO 1983, COMA 1998, CFS2009, WHO1985, COT 2003 and CODEX 2005.

Open Access Original Research Article

On Spaces with the Maximal Number of Conformal Killing Vectors

Carlos Batista

Physical Science International Journal, Page 1-13
DOI: 10.9734/PSIJ/2018/45191

It is natural to expect and simple to prove that every conformally flat space possess the maximal number of conformal Killing vector fields (CKVs). On the other hand, it is interesting to ask whether the converse is true. Is conformal flatness a necessary condition for the existence of the maximal number of CKVs? In this review article it is proven that the answer is yes, a space admits the maximal number of CKVs if, and only if, it is conformally flat.

Open Access Original Research Article

Effect of Milling Equipment on the Level of Heavy Metal Content of Foodstuff

Ebenezer O. Oniya, Omodele E. Olubi, Ayodeji Ibitoye, James I. Agbi, Samuel K. Agbeni, Ebenezer B. Faweya

Physical Science International Journal, Page 1-8
DOI: 10.9734/PSIJ/2018/42572

Aims: This study evaluated the concentration of heavy metal contamination of foodstuff by selected milling equipment (burr mill and hammer mill).

Place and Duration of Study:  Samples collected from a market in Akungba-Akoko Southwestern Nigeria; processed and analysed at Prof. Julius Okojie Central Research laboratory, Federal University of Technology, Akure, Nigeria between January and April, 2018.

Methodology: Selected food samples (yam, plantain, wheat, guinea corn, beans, soya beans, maize and cassava) were sourced randomly from a local market in Akungba-Akoko, Ondo       State, washed with distilled deionised water, sun-dried and milled into their resulting flour   product; a corresponding acid digested sample served as control. Heavy metal analysis of copper, iron, lead, cadmium, chromium and zinc were carried out using atomic absorption spectrophotometry [AAS].

Results: Results revealed that of the milling equipment used in this study, the burr mill introduced the maximum concentration of contaminant into food, while the hammer mill recorded level of contaminant in minimal doses. Fe was predominant in all the milled samples; the metallic composition of the mills being a contributory factor to the level of contamination. Cd was below the detection limit in the analysed samples. Pb and Cr were found to be comparatively higher than the permissible limit of 0.3mg/kg and 2.3mg/kg respectively recommended by WHO/FAO. The concentration range of Cu and Zn were within acceptable limit and presents no risk of intake.

Conclusion: The higher concentration level of metals recorded in the milled samples in comparison to the control shows a level of contamination introduced by the mill.

Open Access Original Research Article

Determination of Reverberation Time and Sound Pressure Level of Selected Lecture Halls in University of Agriculture, Makurdi-Benue State, Nigeria

A. A. McAsule, A. N. Amah, I. Ahemen, F. N. Gesa

Physical Science International Journal, Page 1-9
DOI: 10.9734/PSIJ/2018/44985

Aim: Designing a lecture hall acoustics is a prestigious task which demands high accuracy of acoustical measures such as Reverberation time (T), Sound pressure levels (SPL) among other numerous parameters. In Nigeria however, little is considered about the acoustical environment on stages in lecture halls and how the design of environments are perceived by the users even though most international standards set optimum values of these parameters with respect to room volume and designed purposes.

Study Design: This research has been conducted to examine the values of T and SPL of six selected unoccupied lecture halls in the University of Agriculture, Makurdi. Place and Duration: Department of Physics/ College of Science Federal University of Agriculture, P.M.B.2373 Makurdi-Benue State, Nigeria, between July 2017 to February 2018.

Methodology: The linear dimensions (length, breadth and height) of each lecture hall and the surface areas of the absorbent materials per each lecture hall was measured using the measuring tape . The AutoCAD software was then used for volume computations.

To measure the sound pressure levels (SPLs), equivalent sound pressure levels were registered at each selected point of the halls using a calibrated digital sound level meter (model Extech 407780) at wall distance of 1.00 m and intervals of 10 s in between.

Results: Reverberation Time values were calculated using Sabine’s method. The mean value of T60 was found to be 1.66 s with a standard deviation of 0.36 s. The calculated SPL values were found to have a least value of 63.68 dB (A) in L4 while L6 has the highest value of a dispersion of 84.79 dB (A). In comparison with international guidelines, the reverberation time as well as SPL values found in these lecture halls were not within reference values of 0.40 ≤ T60 ≤ 0.80s and 35dB(A)≤ SPL ≤ 45dB(A) established by International Standard Organization (ISO) 3382, International Electro technical Commission (IEC) 60268 and World Health Organization WHO. Hence the results showed that the selected lecture halls do not meet the current standard of acoustic design set for public speech buildings.