Volume 7 No. 1

September 2011
Surface Imaging of Cold DC Magnetized Air Plasma Treated Poly(dimethyl siloxane) Surfaces

Surface Imaging of Cold DC Magnetized Air Plasma Treated Poly(dimethyl siloxane) Surfaces

pp 24-30 (Vol 7 No. 1 2011)

Myrron Albert C. Aguila 1 a , Ivan B. Culaba 2 b, and Erwin P. Enriquez 3 a
a Department of Physics, Ateneo de Manila University
Loyola Heights, Katipunan Avenue, Quezon City, Philippines
b Department of Chemistry, Ateneo de Manila University
Loyola Heights, Katipunan Avenue, Quezon City, Philippines

1 myrroncaguila@gmail.com
2 culaba@ateneo.edu
3 epenriquez@ateneo.edu

ABSTRACT

The surface morphology of poly(dimethyl siloxane) surfaces treated with cold dc magnetized air plasma had been investigated via scanning electron microscopy. The treatment parameters involved in the study were sample-cathode distance, discharge power, and discharge pressure. The plasma treated PDMS surfaces exhibit a variety of surface structures ranging from cracked film morphology to the presence of disordered buckling and aligned, corrugation depending on the treatment parameter studied.

Comparative Physicochemical Analysis of Regular and Civet Coffee

Comparative Physicochemical Analysis of Regular and Civet Coffee

pp 19-23 (Vol 7 No. 1 2011)

Stephanie Chan 1, Emmanuel Garcia 2
Chemistry Department, De La Salle University Manila
2401 Taft Avenue, 1004Manila, Philippines
1 stephanie.c.chan@dlsu.edu.ph
2 emmanuel.garcia@dlsu.edu.ph

ABSTRACT

Regular and Civet coffee beans of the Coffea robusta variety were analysed for -tocopherol and caffeine contents by HPLC, surface microstructure by SEM, minerals by EDX. Probably due to absorption, the -tocopherol content of the civet coffee beans was lower compared to the regular robusta coffee beans. Heating damages the cell membrane and vacuoles, causing an increased release of -tocopherol and caffeine. Interestingly, calculations showed that roasting produced a more pronounced increase in -tocopherol content in regular robusta than in the civet counterpart. Meanwhile, the caffeine content increase of the Civet coffee beans may be attributed to the possible formation of amino acids which are precursors of caffeine biosynthesis. SEM revealed that civet coffee beans acquired surface micro-pitting due to the action of digestive enzymes. The roasted regular robusta and civet coffee beans showed a smoother surface due to the fusion of cellulose in the cell wall. The mineral content of the civet coffee beans were lower than that of regular robusta which may have been an effect of absorption by the civet.

Antimicrobial Flavonoid from Hibiscus rosa-sinensis Linn.

Antimicrobial Flavonoid from Hibiscus rosa-sinensis Linn.

pp 12-18 (Vol 7 No. 1 2011)

Consolacion Y. Ragasaa 1 ,and Leslie Ann A. Rufino 2
1 Chemistry Department, De La Salle University, 2401 Taft Avenue, Manila 1004, Philippines
2 School of Chemical and Biomedical Sciences, Central Queensland University, Queensland 4701, Queensland, Australia

ABSTRACT

The air-dried flowers of Hibiscus rosa-sinensis Linn., commonly known as gumamela afforded 5,7,4′-trihydroxyflavanone (1), also known as naringenin, and a mixture of hydrocarbons and squalene. The structure of 1 was elucidated by extensive 1D and 2D NMR analyses. Antimicrobial tests on 1 indicated low activity against the bacterium, S. aureus and fungi, C. albicans and T. mentagrophytes. Compound 1 did not exhibit cytotoxicity against a human lung non-small cell adenocarcinoma (A549) cell line and a normal Chinese hamster ovarian (AA8) cell line.

Antimicrobial Coumarin Derivative from Delonix regia

Antimicrobial Coumarin Derivative from Delonix regia

pp 7-11 (Vol 7 No. 1 2011)

Consolacion Y. Ragasa and Joy G. Hofilena
Chemistry Department, De La Salle University, 2401 Taft Avenue, Manila

ABSTRACT

The dichloromethane extract of the air-dried leaves of Delonix regia afforded scopoletin (1) by silica gel chromatography. The structure of 1 was determined by spectroscopic methods and confirmed by comparison of its 1H NMR data with those reported in the literature for scopoletin. Compound 1 exhibited antifungal activity against Candida albicans and antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Bubtilis subtilis. It was inactive against the fungi, Aspergillus niger and Trichophyton mentagrophytes.

Freshman Physics Majors’ Cognitive Expectations and Academic Performance in their Introductory Physics Course

Freshman Physics Majors’ Cognitive Expectations and Academic Performance in their Introductory Physics Course

pp 1-6 (Vol 7 No. 1 2011)

Voltaire Mallari Mistades
Physics Department
De La Salle University
2401 Taft Avenue, Manila

ABSTRACT

The research investigates the extent of change in Physics majors’ cognitive expectations – beliefs about the learning process and the structure of knowledge – after going through their first Introductory Physics course. Using the Maryland Physics Expectations (MPEX) Survey, the students’ responses are compared with the responses of ‘life-long learners of physics’. The students’ post-instruction responses reflected highest agreement with the experts’ response in the Concepts, Reality Link, and Effort Link dimensions of the survey. Analysis of the beliefs profile of the students in the upper quartile compared with the beliefs profile of the students in the lower quartile revealed that a more ‘expert-like’ thinking in the Coherence, Concepts, and Effort Link dimensions is present for the students who performed academically well in class.