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: Populasi kumbang Elaeidobius kamerunicus Faust pada tanaman kelapa sawit Elaeis guneensis Jacq di PTPN VIII Cimulang, Bogor
Abstrak: Elaeidobius kamerunicus (Coleoptera : Curculionidae) is a weevil pollinator of oil palm which used in Indonesia since 1983. The aim of the research were to study the population of weevil and the environmental factors that affected the population of weevil. Weevil populations were observed in male flower of oil palm by stratified random sampling in July, October, and November. Relationship between environmental factors and weevil population were analyzed by Pearson’s correlation using SigmaPlot software version 11.0. Results showed that population of the weevil in November was higher than that in July and October. The population of weevil was affected by number of spikelet per bunch and rain fall.
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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