9 research outputs found
Utilizing Landsat 8 OLI for land cover classification in plantations area
Identifying the land cover in plantations is crucial to assist the management of an area. Today, land cover classification can be achieved using free satellite data. The objective of this study is to perform a supervised classification using LANDSAT 8 OLI to differentiate the land cover in Brumas Camp which consists of non-vegetation, oil palm, forest, and forest plantations. The overall accuracy and Kappa’s coefficients were 71.64% and 0.62, respectively. We found out that the accuracy of classification for non-vegetation is relatively higher compared to vegetation land cover types. The non-vegetation land cover has distinct spectral reflectance which is useful to differentiate between non-vegetation and vegetation land covers
Antimicrobial resistance profile of Salmonella present in organic farming in Selangor, Malaysia
Presence of Salmonella in organic farming may lead to contamination in fresh produce. This study was designed to detect Salmonella contamination in organic vegetable farm situated in Serdang and to evaluate the antibiotic susceptibility profiles of the isolates. A total of 460 samples of brinjal, cucumber, ladies’ fingers and soil were collected and examined for the presence of Salmonella. The obtained isolates were identified and confirmed by biochemical characterization and serotyping. Antibiotic sensitivity profiles of the isolates were determined by using agar disk diffusion method. Salmonella spp. was detected in brinjal (1.7%, n=2), cucumber (1.7%, n=2), ladies’ fingers (2.5%, n=3) and soil (5.0%, n=5) samples. The prevalent serovars were Salmonella enterica ser. Senftenberg, S. enterica ser. Weltevreden and S. enterica ser. Corvallis. All strains were resistance to penicillin and vancomycin, with multiple antibiotic resistance (MAR) index between 0.21 and 0.36, demonstrated here as multi-drug resistant (MDR) Salmonella. The result highlighted that organic vegetables constituted potential sources of Salmonella, informing continuous monitoring and tightened surveillance are necessary to ensure food safety
DFT investigations of structural and electronic properties of gallium arsenide (GAAS)
First principles calculations for structural and electronic properties of GaAs have been reported using a full potential linearized augmented plane wave (FP-LAPW) scheme of calculations developed within density functional theory (DFT). We use in this study local density approximation (LDA), Perdew-Burke-Ernzerhof parameterized generalized gradient approximation (PBE-GGA), Wu-Cohen parameterized GGA (WC-GGA) executed in WIEN2k code. In addition, to calculate band structure with high accuracy we used modified Becke-Johnson exchange potential (MBJ) + LDA approach. Our calculated lattice constant with GGA-WC is in good agreement to experimental value than LDA and PBE-GGA. Whereas our calculations for the band structure show that MBJ+ LDA approach gives much better results for band gap value as compared to other exchange correlation approaches
Optoelectronic Structure and Related Transport Properties of Ag2Sb2O6 and Cd2Sb2O7
PomocĂ metody the full-potential linearized augmented-plane wave byla zkoumána elektronická struktura a termoelektrickĂ© vlastnosti Ag2Sb2O6 a Cd2Sb2O7. ModifikovanĂ˝ potenciál Becke-Johnson byl aplikován k vĂ˝mÄ›nÄ› korelaÄŤnĂ energie. ElektronickĂ© pásmovĂ© struktury odhalujĂ, Ĺľe minimálnĂ hodnota valenÄŤnĂho pásma a minimálnĂ pásmo vodivosti se vyskytujĂ v bodÄ› C, coĹľ naznaÄŤuje, Ĺľe Ag2Sb2O6 a Cd2Sb2O7 majĂ pĹ™ĂmĂ© polovodiÄŤovĂ© energetickĂ© pásmo. Vyskytla se silná hybridizace mezi stavy Ag (Cd) -s / p a O-s / p. OptickĂ© vlastnosti, tj. KomplexnĂ dielektrická funkce, odrazivost, index lomu a funkce ztráty energie, odhalujĂ vysokou odrazivost v oblasti ultrafialovĂ© energie, coĹľ ukazuje na uĹľiteÄŤnost tÄ›chto materiálĹŻ na stĂnÄ›nĂ vysokoenergetickĂ˝ch zářenĂ. KombinacĂ transportnĂ teorie a metody from the full-potential linearized augmented-plane wave byly termoelektrickĂ© vlastnosti analyzovány jako funkce teploty. Vzhledem k vysokĂ©mu tepelnĂ©mu vĂ˝konu a ĂşzkĂ©mu pásmu jsou Ag2Sb2O6 a Cd2Sb2O7 vhodnĂ˝mi materiály pro pouĹľitĂ v optoelektronickĂ˝ch a termoelektrickĂ˝ch zaĹ™ĂzenĂch.Using the full-potential linearized augmented-plane wave method, the electronic structure and thermoelectric properties of Ag2Sb2O6 and Cd2Sb2O7compounds have been explored. The modified Becke–Johnson potential was applied to treat the exchange–correlation energy term. The electronic band structures reveal that the valence-band maximum and conduction-band minimum occur at C point, indicating that Ag2Sb2O6 and Cd2Sb2O7 are direct energy bandgap semiconductors. Strong hybridization appeared between Ag (Cd)-s/p and O-s/p states. The optical properties, i.e., complex dielectric function, reflectivity, refractive index, and energy loss function, reveal high reflectivity in the ultraviolet energy range, indicating usefulness of these materials in shields from high-energy radiation. Combining transport theory and the outputs from the full-potential linearized augmented-plane wave calculations, the thermoelectric properties were analyzed as functions of temperature. Due to their high thermopower and narrow bandgap, Ag2Sb2O6 and Cd2Sb2O7 are suitable materials for application in optoelectronic and thermoelectric devices