SDinside front cover-jan.-june2018.pmd January-June 2018 • Vol. 30 No. 1 INTERNATIONAL ADVISORY BOARD Science Diliman ISSN 0115-7809 SCIENCE DILIMAN is published semi-annually (June and December) by the University of the Philippines Diliman through the Off ice of the Vice-Chancellor for Research and Development. The journal features articles of pure and applied sciences. Editorial Board Editor in Chief Irene M. Villaseñor, Ph.D. University of the Philippines Associate Editors Jose Maria P. Balmaceda, Ph.D. University of the Philippines Louis Angelo M. Danao, Ph.D. University of the Philippines Carlos Primo C. David, Ph.D. University of the Philippines Christian N. Della, Ph.D. University of Glasgow Singapore Alonzo A. Gabriel, Ph.D. University of the Philippines Arnold M. Guloy, Ph.D. University of Houston Gil S. Jacinto, Ph.D. University of the Philippines Dennis I. Merino, Ph.D. Southeastern Louisiana University Jonas P. Quilang, Ph.D. University of the Philippines Arnel A. Salvador, Ph.D. University of the Philippines Terence P. Tumolva, D.Eng. University of the Philippines Managing Editor Gonzalo A. Campoamor II, Ph.D. University of the Philippines Editorial Assistant Narita E.C. de las Alas Layout Artist Dercylis G. Mararac Copyeditor Sarah Mae U. Penir On the Cover: Images from the researches of Metillo et al. , Montaño et al. , Penuliar et al. and Bernardo and de Leon. Teofilo A. Abrajano, Jr., Ph.D. King Abdullah University of Science and Technology Kingdom of Saudi Arabia Rigoberto C. Advincula, Ph.D. Case School of Engineering Case Western Reserve University, USA Kenneth Buckle, Ph.D. Food Science and Technology Group School of Chemical Sciences and Engineering The University of New South Wales, Australia Jose B. Cruz, Jr., Ph.D. Department of Electrical and Computer Engineering The Ohio State University, USA John P. Encarnacion, Ph.D. Department of Earth and Atmospheric Sciences Saint Louis University, USA Mihali A. Felipe, Ph.D. Gerstein Lab, Bioinformatics Yale University, USA Robert J. Howell, Ph.D. Department of Mechanical Engineering The University of Sheff ield, United Kingdom Jeanmaire E. Molina, Ph.D. Department of Biology Long Island University, Brooklyn, USA Rudolf A. Roemer, Ph.D. Centre for Scientif ic Computing and Department of Physics University of Warwick, United Kingdom Raul K. Suarez, Ph.D. Department of Ecology, Evolution and Marine Biology University of California, Sta. Barbara, USA Myra O. Villareal, Ph.D. Life and Environmental Sciences University of Tsukuba, Japan Contents of this journal may not be reproduced without the publisher’s written permission except for fair use, i.e. , for personal, educational and research purposes, in accordance with copyright law. Reprinting and republication in any other journal or compilation is likewise prohibited except as provided in the Publication Agreement when the author reprints his/her article for inclusion in any publication where he/she is the author or editor, subject to giving proper credit to the original publication of the article in the journal. The views expressed in the articles are those of the authors and do not necessarily reflect the views of the publisher and the editors.