Judul: Pembuatan Sel Surya Berbasis Film Ferroelektrik Barium Strontium Titanate (Ba0,5Sr0,5TiO3)
Abstrak: Growth of films Ba0,5Sr0,5TiO3 (BST) 1 M has been done with variation of annealing in hold time 8 hours, 15 hours, 22 hours, and 29 hours at constant temperature 8500C, above Si (100) substrate p-type, by using the sol-gel process method which followed with spin coating process at 3000 rpm for 30 seconds. Optics spectroscopy shows that BST film solar cells with annealing hold time 8 hours, 15 hours, and 22 hours, works effectively in wavelength ≥ 700 nm absorption range. Yet for sample with annealing hold time about 29 hours effectively absorb in ≤ 700 nm wavelength range. It obtained BST film refractive index at range 2.0 to 7.0 to wavelength range ±370-870 nm. Band gap BST film value based on annealing hold time 8 hours, 15 hours, 22 hours, and 29 hours respectively 2.60 eV; 3.12 eV: 3.24 eV, and 2.66 eV. Electrical conductivity value which obtained, indicate that the BST film is classified as semiconductor material with conductivity order 10-5-10-4 S / cm. The result of I-V photovoltaic characterization shows the BST film potentially to be a solar cells device with efficiency according to the annealing hold time 8 hours, 15 hours, 22 hours, and 29 hours in a row are 2.68x10-5%, 3.51x10-5%, 4.53x10-5% and 3.22x10-5%
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Judul: Pembuatan dan Karakterisasi Film Ba0.4Sr0.6Ti03 Dibandingkan dengan Film Ba0.5Sr0.5Ti03
Abstrak: Penelitian dengan menggunakan film Ba0,4Sr0,6TiO3 (BST) dibandingkan dengan film Ba0,5Sr0,5Ti03 berdasarkan karakterisasi sifat optik, listrik, dan sensitifitas dengan metode yang sama yaitu sol gel dengan teknik spin coating pada kecepatan putar 3000 rpm selama 30 detik. Proses pembuatan fotodioda Ba0,4Sr0,6Ti03 dengan menumbuhkannya di permukaan substrat Si(100) type-p pada konsentrasi 1 M dan proses annealing pada variasi suhu yaitu 800oC, 850oC, 900oC dengan waktu masing-masing 15 jam. Karakterisasi I-V dilakukan pada kondisi terang dan gelap dengan filter warna hijau, kuning dan merah. Hasil yang diperoleh menunjukkan bahwa film bersifat fotodioda. Konduktivitas listrik (σ) dengan variasi suhu 800oC, 850oC, 900oC berturut-turut yaitu 0,36 x 10-4 S/m, 3,77 x 10-4 S/m, 50,25 x 10-5 S/m. Nilai σ tersebut berada dalam rentang σ semikonduktor, sehingga film BST yang dihasilkan merupakan material semikonduktor sedangkan pada karakterisasi konstanta dielektrik (𝜀) dengan variasi tegangan yaitu 1 volt, 2 volt dan 5 volt yang masing-masing pada suhu 800oC, 850oC, 900oC dapat disimpulkan bahwa konstanta dielektrik bahan semakin besar akibat bertambahnya tegangan. Karakteristik sifat optik dilakukan pada pengukuran absorbansi dan reflektansi film. Pada suhu 800oC, 850oC, 900oC berdasarkan kurva absorbansi yang diperoleh memperlihatkan panjang gelombang yang paling banyak diserap dan dipantulkan berturut-turut yaitu berkisar 340-430 nm, 345-520 nm, 340-1020 nm.
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Judul: Phylogeography and Species Limits in the Papuan White Snake (Micropechis ikaheka) (Reptilia: Serpentes: Elapidae)
Abstrak: Papua white snake, Micropechis ikaheka, has been distingushed into two subspecies M.i. ikaheka and M.i. fasciatus. However, due to lack of data on their morphology, distribution and ecology, both subspecies often ignored in scintific discussions and refers only byas , Micropechis ikaheka. This study was designed to document the differences between M.i. ikaheka and M.i fasciatus by using scales characteristics and reproductive organ or hemipenes. The study also examine, zoogeography, habitat, diet and cannibalism of both subspecies to better understanding the the ecology of one of the most venomous snakes in the world. This study consists of three topics with method and also different in the size samples, respectively. The first study is the histology and microtopography of the skin were studied using paraffin method and Scanning Electron Microscope (SEM). The second is the hemipenis were examined by following Myers and Cadle (2003), and Zaher and Prudente (2003). The third is the abdominal surgery was carried out to document diet type and the investigate phenomenon of cannibalism in the snake. Specimens for this study came from the collection from Museum Zoologicum Bogoriense (MZB) and Universitas Negeri Papua’s Laboratory (LZU). The research result also indicated that the markers of skin and hemipenis described the same structure and microornamentation in all M. ikaheka groups being compared. Based specimens examined morphological descriptions do not s support the further differentiation in Micropechis. In short, two markers that used in this study could not sufficiently indicate the differences in the level of species and subspecies of M. ikaheka. The study, however, were able to delineate zoogeography and skin color patterns, which fall into four groups: M. i. ikaheka; M. i. fasciatus. M. i. ssp. “intermediate”; and M. i. ssp “black”. This study also revealed that color variations did not overlap in their geographic distribution. It is therefore, it suggested that environmental factors may contribute to the skin color variations. It also assumed that habitat discontinuous and biogeography factors may also cause the loss of the connection between the original populations (vicarians) or follow colonization events (dispersal). The examined of 22 stomach contents of M. ikaheka shows this species is carnivorous, and prey on vertebrates such as amphibians, fish, reptiles, and Mammals. These snakes are opportunistic predators since they prey on all that can be captured, but mainly reptiles (61.5%), followed by mammals and fish (both 15.4%), and amphibians (7.7%). Although categorized as terrestrial animal, the diet study showed that M. ikaheka snakes often go into the water to hunt for fish (the sample from Yapen island), including eel (the sample from Aru island). Based on prey items indentified, there is evidence that M. ikaheka is cannibal. At this time, there still no record on reason for cannibalism, but it is assumed that cannibalism was due to competition between populations and means to control population.
Keyword: geographic variation, white snake, papua