Asian Journal of Physical and Chemical Sciences <p style="text-align: justify;"><strong>Asian Journal of Physical and Chemical Sciences (ISSN: 2456-7779)</strong> aims to publish high quality papers (<a href="/index.php/AJOPACS/general-guideline-for-authors">Click here for Types of paper</a>) in all areas of Physics, Chemistry and Earth Sciences. The journal also encourages the submission of useful reports of negative results. This is a quality controlled, OPEN peer reviewed, open access INTERNATIONAL journal.</p> SCIENCEDOMAIN international en-US Asian Journal of Physical and Chemical Sciences 2456-7779 Reaction Kinetics of Iron Oxides in Ok Tedi Magnetite Skarn Ore <p>Magnetic skarn ore (MSO) is one of the major copper bearing ore extracted by the Ok Tedi Copper Mine in Papua New Guinea (PNG). Copper minerals are recovered by flotation while the iron not associated with copper are discarded as tailings. The objective of this investigation was to determine the iron ore reduction kinetics for the Ok Tedi MSO and ascertain if it can be processed to produce sponge iron for a mini steel plant in Papua New Guinea. SEM-EDAX analyses of the Ok Tedi MSO indicated 10.1% C, 30% O, 0.6% Mg, 1.1% Si, 21.1% S, 0.8% Ca and 36.2 % Fe. Most of the iron is in sulfide form. Both naturally occurring and roasted sinters of Ok Tedi MSO samples of different particle sizes were reduced by charcoal carbon at three different temperatures and seven different reduction times. Analyses of the reduced products indicated a metallic iron content of more than 65 wt. % on average. Results showed that there was no significant difference in reduction between fluxed and control materials. Only a slight increase in kinetics with reduced particle size, hence the reaction rate constant (K) did not vary much within the temperatures investigated. Reaction kinetics increases with increasing reduction time at 900°C. Therefore, more iron reduction is observed with particles of 106 µm size. In addition, the results also confirmed that the reduction energy used was higher at 800°C and lower at 1000°C. In conclusion, iron reduction can be improved but close monitoring of temperature and reduction times are essential to determine the reaction kinetics of the Ok Tedi MSO.</p> Mary Kama Kaul Gena Tindi Seje Nuru ##submission.copyrightStatement## 2020-10-25 2020-10-25 1 13 10.9734/ajopacs/2020/v8i430121 Distribution and Variation of Potassium in Black Soil at Different Stages of Crop Growth in Maize (Zea mays) <p>Potassium (K) is the third most important major plant nutrient with numerous functions. The availability of K depends on concentration relative to that of Ca<sup>2+</sup> and Mg<sup>2+</sup> than on the total quantity of K present. The level of extraction of K by different extractants followed the order: boiling HNO<sub>3</sub> (1 <em>M</em>) &gt; Non- exchangeable K &gt; Exchangeable K &gt; Water soluble K. The amount of K extracted by different extractants was more in non- calcareous soil followed by calcareous soil. To know the K availability in both the soils, a pot culture experiment was conducted with the two soils (i.e., calcareous and non-calcareous) to know the response of maize to K application. Results showed that a significant higher value of available K in calcareous soil under potassium @ 120 kg K<sub>2</sub>O ha<sup>-1</sup> treatment followed by 80 kg K<sub>2</sub>O ha<sup>-1</sup> in non-calcareous soil irrespective of critical growth stages of hybrid maize. Among the K fractions, water soluble K was the least in magnitude and lattice K was found to be dominant one. Application of 120 kg K<sub>2</sub>O ha<sup>-1</sup> recorded the highest potassium in all the K fractions (water soluble K, exchangeable K and nitric acid soluble K) in all stages of crop growth in calcareous soil whereas in non-calcareous soil 80 kg K<sub>2</sub>O ha<sup>-1</sup> recorded high in all the fractions and the results emphasizing the importance of potassium in soil. Grain and straw yield of hybrid maize were significantly higher under 120 kg K<sub>2</sub>O ha<sup>-1</sup>in calcareous soil and 80 kg K<sub>2</sub>O ha<sup>-1</sup> in non- calcareous soil which is well evidenced by a yield increase of 37.7 % over control. A significant and positive correlation was existing between all fractions of potassium viz., HNO<sub>3</sub> soluble K, non- exchangeable K, exchangeable K, water soluble K and available K with grain and stover yield in calcareous soil and non- calcareous soil. It was found that calcareous soil showed comparatively better response to the application of potassium especially in water soluble K with an R<sup>2</sup> value of 0.917** followed by HNO<sub>3</sub> soluble K with a R<sup>2</sup> value of 0.895**. Therefore, the present investigation stresses the vital importance of inclusion of higher dose of potassium in calcareous soil for maintaining soil K dynamics and enhancing yield of hybrid maize so as to sustain soil productivity.</p> R. Gnanasundari K. M. Sellamuthu P. Malathi ##submission.copyrightStatement## 2020-10-27 2020-10-27 14 21 10.9734/ajopacs/2020/v8i430122 Stabilizing Ag Nanoparticles Using Anatase TiO2 and Cu on Al Surface <p>Chemical adsorption of anatase TiO<sub>2</sub>, silver nanoparticles (Ag NPs), and Cu particles (Cu Ps) on aluminum (Al) surface yielded an active surface-enhanced Raman scattering (SERS) substrate. TiO<sub>2</sub> is known to reduce both silver (Ag) and copper (Cu). In an oxidizing environment, Ag NPs remain unoxidized since Cu has a more negative redox potential than Ag. Ag is therefore protected by Cu from getting oxidized. Although Ag NPs exhibit better SERS activity than Au NPs, Ag is relatively easier to oxidize, limiting the development of Ag-based nanomaterials. Therefore, despite the poor SERS activity of Au nanoparticles than that of Ag nanoparticles, Au nanoparticles have been widely used. Herein, the stabilization of Ag nanoparticles by incorporating a reductive process using anatase TiO<sub>2</sub> is reported. The fabricated substrates bearing anatase, Ag NPs, and Cu Ps were stable, as seen by Raman spectra, and remained unchanged for more than 2&nbsp;months.</p> Masayoshi Kaneko ##submission.copyrightStatement## 2020-11-12 2020-11-12 22 30 10.9734/ajopacs/2020/v8i430123