(January 20)— Science Diliman Volume 27, No. 2 (2015) is now online. The current issue features four articles.

The first article “Trace Invariance for Quaternion Matrices” by Ralph John de la Cruz discusses the classical result in linear algebra concerning the trace of matrices with complex entries and determines whether this result holds true for the set of quaternion (used in quantum mechanics and 3D animation in computing movement and rotation) matrices.

The second article co-authored by Marry Donnabelle L. Balela and Kathy Lois S. Amores is entitled “Formation of Highly Antimicrobial Copper Nanoparticles by Electroless Deposition in Water.” The study is about the fabrication or production of copper nanoparticles, with excellent bacterial killing property, in response to the alarming occurrence of antibiotic-resistant bacteria. According to the authors, new materials, specifically metallic nanoparticles, are being explored as new generation antimicrobial agents.

“Status Assessment of Clarias Species in the Philippines: Insights from DNA Barcodes” shed light on the identity (native or introduced) of the three freshwater catfishes of the genus Clarias collected from Agusan Marsh. Prior to their study there were conflicting claims on these species reported in the Philippines. Through DNA barcoding and analysis of all barcodes available in GenBank, the study established that Clarias batrachus and Clarias macrocephalus are native or naturally occurring in the Philippines, whereas Clarias gariepinus is an introduced species. Brian S. Santos, Francis Peter C. Vesagas, Marc Timothy C. Tan, Joycelyn C. Jumawan and Jonas P. Quilang wrote the article

The last article entitled “Optimizing Microwave-assisted Crude Butter Extraction from Carabao Mango (Magnifera indica) Kernels ” is by Edgardo V. Casas, Von Jansen G. Comedia, Arni G. Gilbuena and Kevin F. Yaptenco. The paper discusses the mechanical screw extraction of mango butter from waste carabao mango seed kernels through the use of microwave. Sensory evaluation of the mango butter revealed in can be used as a substitute to cocoa butter and as potential additives to cosmetics and skin care products.

Science Diliman is a Philippine Journal of Pure and Applied Science. It has a “Category A” rating (credited as an international level publication) from the Commission on Higher Education.

Printed copies will be available by March 2016. — Bino C. Gamba