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Random sampling of research papers from Philippine-based researchers

Sharing a random sampling of this week’s research papers from Philippine-based researchers. Jaculbia, et al, reported an enhancement of terahertz emission from SI-GaAs and n-GaAs wafer surfaces by more than a factor of 2 and 4, respectively, in Applied Surface Science. Using phenotypic features and mitochondrial DNA, Willette and Paddin reported in the Journal of Applied Ichthyology the taxonomic relationship between specimens of marine jacks in Taal Lake. Beja revisited the issue whether there is significant difference in happiness between a housewife and a working wife and reported the findings in Applied Research in Quality of Life. Finally, Dizon et al used numerical analysis of the mechanical stress distribution within coated conductor tapes to explain the observed behavior in the evaluation of the tapes’ delamination strength in a paper published in Superconductor Science and Technology. More details below.

Enhanced terahertz emission from GaAs substrates deposited with aluminum nitride films caused by high interface electric fields
Jaculbia, RB; Balgos, MHM; Mangila, NS; Tumanguil, MAC; Estacio, ES; Salvador, AA; Somintac, AS
Applied Surface Science 303 (2014) 241-244

We report on the enhanced terahertz (THz) emission from SI-GaAs and n-GaAs wafer surfaces grown with aluminum nitride (AlN) thin films, by more than a factor of 2 and 4, respectively. This is attributed to the increased GaAs surface electric field as confirmed by calculations and photoreflectance measurements. The deposition of AlN on an n-InAs substrate, however, produces no change in the THz emission despite the presence of a strong field as obtained from calculations. These results show that for semiconductors in which the THz radiation is primarily due to drift current, an increase in interface electric field results to an increase in the THz emission. For semiconductors whose primary source of THz radiation is carrier diffusion however, an increase in the interface electric field has a no effect in THz emission intensity.

Identifying the biodiversity of marine jacks ( Carangidae) in the freshwater Taal Lake, Philippines using phenotypic features and mitochondrial DNA
Willette, DA; Padin, JIM
Journal of Applied Ichthyology 30 (2014) 490-495

Jacks, members of the genus Caranx (Perciformes: Carangidae), comprise economically-important marine fisheries across the world. In the Philippines, this valued fishery extends from the marine environment into a freshwater volcanic lake, Taal Lake. Two jacks, Caranx ignobilis (Forsskal, 1775) and C.sexfasciatus (Quoy and Gaimard, 1825), have long been reported from the lake, with recent molecular evidence alluding to genetic divergence between marine and freshwater populations. Here, a combination of phenotypic features and the mitochondrial Cytochrome oxidase b gene region were used explicitly to profile the taxonomic relationship between marine and freshwater specimens of C.ignobilis and C.sexfasciatus. Using molecular data from all known Philippine Caranx species, a partial phylogeny of the genus was reconstructed and contrasted to observed colouration, morphological and meristic features. Findings include the first report of C.papuensis, in Taal Lake; however, previous reports of C.sexfasciatus are not validated. Caranx ignobilis was confirmed present, yet several morphological features were unique to lake specimens, including red instead of yellow colouration of the lower jaw, anal fins, and caudal peduncle, and four instead of two canine teeth. Further, C.ignobilis sequence distance was 6.3% between marine and lake specimens, whereas C.papuensis distance was 0.2%. The combined molecular and phenotypic data suggest that Taal Lake C.ignobilis may represent an evolutionarily unique lineage. These data are significant for developing management strategies that have typically overlooked the ecological and evolutionary attributes of the jack fishery.

Who is Happier: Housewife or Working Wife?
Beja, EL
Applied Research in Quality of Life 9 (2014) 157-177

Earlier research found no statistically significant difference in the happiness between a housewife and a working wife. However, there is now an expectation that a difference in their happiness exists today given the changes in the role of women in society. This paper revisits the issue using data from the 2000s. Results show that there is no difference in the happiness between a housewife and a working wife in the upper- and low-income economies. In contrast, results for the middle-income economies show that a part-time working wife is happier than a housewife and that both part-time working wife and housewife are happier than a full-time working wife.

Numerical analysis of stress distribution in Cu-stabilized GdBCO CC tapes during anvil tests for the evaluation of transverse delamination strength
Dizon, JRC; Gorospe, AB; Shin, HS
Superconductor Science and Technology 27 (2014) 055023

Rare-earth-Ba-Cu-O (REBCO) based coated conductors (CCs) are now being used for electric device applications. For coil-based applications such as motors, generators and magnets, the CC tape needs to have robust mechanical strength along both the longitudinal and transverse directions. The CC tape in these coils is subjected to transverse tensile stresses during cool-down and operation, which results in delamination within and between constituent layers. In this study, in order to explain the behaviour observed in the evaluation of c-axis delamination strength in Cu-stabilized GdBCO CC tapes by anvil tests, numerical analysis of the mechanical stress distribution within the CC tape has been performed. The upper anvil size was varied in the analysis to understand the effect of anvil size on stress distribution within the multilayered CC tape, which is closely related to the delamination strength, delamination mode and delamination sites that were experimentally observed. The numerical simulation results showed that, when an anvil size covering the whole tape width was used, the REBCO coating film was subjected to the largest stress, which could result in low mechanical delamination and electromechanical delamination strengths. Meanwhile, when smaller-sized anvils were used, the copper stabilizer layer would experience the largest stress among all the constituent layers of the CC tape, which could result in higher mechanical and electromechanical delamination strengths, as well as high scattering of both of these delamination strengths. As a whole, the numerical simulation results could explain the damage evolution observed in CC tapes tested under transverse tensile stress, as well as the transverse tensile stress response of the critical current, I-c.



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