Gadjah Mada University

About: Gadjah Mada University is a education organization based out in Yogyakarta, Indonesia. It is known for research contribution in the topics: Population & Adsorption. The organization has 17307 authors who have published 21389 publications receiving 116561 citations. The organization is also known as: University of Gajah Mada & Universitas Gadjah Mada.

The water absorption, mechanical and thermal properties of chemically treated woven fan palm reinforced polyester composites

Abstract: This study aims to investigate the effect of silane, alkali, and a combination of alkali–silane treatments on the water absorption behavior, mechanical and thermal properties of woven fan palm fibers (WFP)-reinforced unsaturated polyester composites. Maximum moisture content (Mm) and diffusivity (D) values of treated WFP composites immersed in 3.5% NaCl solution both at room temperature and 60 °C were found to be lower than those of untreated WFP composite. The water absorption patterns of the composites immersed at room temperature were found to follow Fickian behavior, contrary to those immersed at 60 °C. The chemical treatments enhanced significantly the tensile and flexural strength of WFP composites. The water absorption reduced drastically the tensile, flexural, and impact strength of WFP composites. The tensile, flexural and impact strength of the treated composites immersed at 60 °C was lower than at room temperature. The thermal stability of alkali-treated WFP composite was slight higher than that for the untreated and silane-treated WFP composites.

Spatial modelling of malaria cases associated with environmental factors in South Sumatra, Indonesia.

Abstract: Malaria, a parasitic infection, is a life-threatening disease in South Sumatra Province, Indonesia. This study aimed to investigate the spatial association between malaria occurrence and environmental risk factors. The number of confirmed malaria cases was analysed for the year 2013 from the routine reporting of the Provincial Health Office of South Sumatra. The cases were spread over 436 out of 1613 villages. Six potential ecological predictors of malaria cases were analysed in the different regions using ordinary least square (OLS) and geographically weighted regression (GWR). The global pattern and spatial variability of associations between malaria cases and the selected potential ecological predictors was explored. The importance of different environmental and geographic parameters for malaria was shown at global and village-level in South Sumatra, Indonesia. The independent variables altitude, distance from forest, and rainfall in global OLS were significantly associated with malaria cases. However, as shown by GWR model and in line with recent reviews, the relationship between malaria and environmental factors in South Sumatra strongly varied spatially in different regions. A more in-depth understanding of local ecological factors influencing malaria disease as shown in present study may not only be useful for developing sustainable regional malaria control programmes, but can also benefit malaria elimination efforts at village level.

Strong Rashba effect in the localized impurity states of halogen-doped monolayer PtSe 2

Abstract: The recent epitaxial growth of the $1T$ phase of the ${\mathrm{PtSe}}_{2}$ monolayer (ML) has opened the possibility for novel applications, in particular for a spintronics device. However, in contrast to the $2H$ phase of transition-metal dichalcogenides (TMDs), the absence of spin splitting in the ${\mathrm{PtSe}}_{2}$ ML may limit the functionality for spintronics application. Through fully relativistic density-functional theory calculations, we show that large spin splitting can be induced in the ${\mathrm{PtSe}}_{2}$ ML by introducing a substitutional halogen impurity. Depending on the atomic number $Z$ of the halogen dopants, we observe an enhancement of the spin splitting in the localized impurity states (LIS), which is due to the increased contribution of the $p\text{\ensuremath{-}}d$ orbital coupling. More importantly, we identify very large Rashba splitting in the LIS near the Fermi level around the $\mathrm{\ensuremath{\Gamma}}$ point characterized by hexagonal warping of the Fermi surface. We show that the Rashba splitting can be controlled by adjusting the doping concentration. Therefore, this work provides a possible way to induce significant Rashba splitting in the two-dimensional TMDs, which is useful for spintronic devices operating at room temperature.