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: Populasi Kumbang Elaeidobius kamerunicus Faust. (Curculionidae : Coleoptera) pada Bunga Jantan Tanaman Kelapa Sawit (Elaeis guineensis Jacq.).
Abstrak: Elaeidobius kamerunicus is a weevil pollinator of oil palm. The weevil is host specifics on male flower of oil palm. Population of E. kamerunicus in oil palm plantation is useful to increase fruit set. Fruit set of oil palm depends on pollination. This study addressed to know population of the weevil and environmental factors that affected the weevil population on oil palm. Weevil populations were observed in male flower of oil palm by sampling method in December 2009, February, and March 2010. Relationship between environment factors and weevil population were analyzed by Pearson’s correlation with Sigmaplot software version 11.0. Results showed that population of the weevil in December 2009 was higher than that in February and March 2010. Number of spikelet per bunch was significantly affected to the weevil population
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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