Judul: Weevil Elaeidobius kamerunicus Faust Population in Oil Palm (Elaeis guineensis Jacq) at PTPN VIII Kebun Sukamaju, Cikidang, Sukabumi
Abstrak: High productivity of oil palm is affected bypollination. Elaeidobius kamerunicus is weevil pollinator that can increase fruit set of oil palm. Weevil population was influenced by natality, mortality, and migration. The objective of this research were to study weevil E. kamerunicus population and environmental factors on oil palm estate at Sukamaju, Cikidang, Sukabumi. Weevil population were observed by stratified random sampling method in male flowers were located at three blocks of the estate on Juny, August, and October 2010. Sex ratio of female and male weevil was counted. Relationship between environmental factors and weevil population were analyzed by Pearson correlation. The highest population of weevil occured in August.Weevil population at Sukamaju was lower than the minimum weevil population for optimum pollination. Sex ratio of female and male weevil during observation was 3:1. Rainfall has the highest effect to weevil population among parameters measured.
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Judul: Demography and Population of Elaeidobius kamerunicus Faust (Coleoptera:Curculionidae) as a Pollinator of Oil Palm (Elaeis guineensis Jacq) in PT. Agri Andalas Plantation, Bengkulu Province
Abstrak: Elaeidobius kamerunicus is an insect pollinator of oil palm. These weevil live and thrive in the male flowers of oil palm. The aims of the research were to study demography and population of E. kameunicus in male flower of oil palm. Demography study of the weevil were observed in the laboratory. One individual male and female of weevil were reared in the box, feeding by one spikelet of male flower. Observation of demographic study were conducted from 2nd day after rearing, until the weevil died. Populations of E. kamerunicus in oil palm plantations were measured by using a sampling method. We selected nine spikelet per bunch of male flower and counted the number of weevil per spikelet. The number of weevil per spikelet and number of spikelet per bunch were counted to determine the number of weevil per bunch. We counted the numbers of anthesis male flower per hectare to determine the number of weevil per hectare. Environmental parameters i.e temperature, humidity, light intensity, and rainfall were measured. The relationship between weevil population and environmental parameters were analyzed by Principal Component Analysis (PCA). Results showed that weevil E. kamerunicus tooks 14-17 days to grow from egg to imago. Statistics demography of the weevil were: generation time (T) was 19 days, gross reproduction rate (G) was 11 individuals, the net reproductive rate (Ro) was 5 individual and intrinsic growth rate (r) was 0.24. Population of the weevil on oil palm age 3 and 6 years were higher in January (41.102 individuals per hectare) and February (153.226 individuals per hectare). While, the lower population of the weevil were found in March (22.618 individuals per hectare) and April (98.693 individuals per hectare). In average, fruit set of oil palm age 3 and 6 years were 82,8% and 83,3%, respectively.
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Judul: Effects of NaMnN2 Material Phase Differences on the Properties and Performance of Sodium Ion Battery Cathodes
Abstrak: Kemajuan teknologi menyebabkan kebutuhan akan baterai isi ulang meningkat. Namun baterai ion litium sebagai baterai yang umum digunakan mengalami kenaikan harga yang tinggi karena kelangkaan litium di alam. Baterai ion natrium sebagai baterai alternatif dari baterai ion litium belum menemukan kandidat material katoda yang tepat. NaMnN2 dari keluarga Layered N-based TMDs-like diharapkan dapat menjadi material katoda baterai ion natrium yang murah dan baik. Density Functional Theory digunakan dalam penelitian ini untuk membuktikan pengaruh fasa terhadap sifat elektronik dan performansi material katoda NaMnN2, sehingga dapat diperoleh fasa terbaik bagi keluarga Layered N-based TMDs-like sebagai katoda baterai ion natrium. Hasil penelitian menunjukan bahwa secara teoretis NaMnN2 berpotensi sebagai katoda baterai ion natrium yang memiliki performansi baik. Selain itu, NaMnN2 fasa 2H memiliki keunggulan pada kestabilan siklus, memiliki konduktivitas yang sangat baik, serta mengalami difusivitas ion Na yang baik dengan energi penghalang sebesar 0,41 eV. Material NaMnN2 fasa 1T unggul dalam tegangan yang lebih tinggi, mencapai 3,93 V, serta memiliki rapat energi yang besarnya mencapai 995,22 Wh/kg., Technological advancements have caused the need for rechargeable batteries to increase. However, lithium ion battery as a commonly used battery has experienced a high price increase due to the scarcity of lithium in nature. Sodium ion battery as an alternative battery to lithium ion battery has not found the right cathode material candidate. NaMnN2 from the Layered N-based TMDs-like family is expected to be a cheap and good sodium ion battery cathode material. Density Functional Theory is used in this study to prove the effect of phase on the electronic properties and performance of NaMnN2 cathode material, so that the best phase can be obtained for the Layered N-based TMDs-like family as a sodium ion battery cathode. The results showed that theoretically NaMnN2 has the potential as a cathode of sodium ion battery which has good performance. In addition, 2H-phase of NaMnN2 has advantages in cycle stability, has excellent conductivity, and experiences good sodium ion diffusivity with a barrier energy of 0,41 eV. The 1T phase NaMnN2 material excels in higher voltages, reaching 3,93 V, and has an energy density of up to 995,22 Wh/kg.
Keyword: cathode, DFT, phase, Quantum Espresso, SIB