Judul: Populasi dan Musuh Alami Telur Penggerek Batang Jagung Asia Ostrinia furnacalis Guenée (Lepidoptera: Crambidae) di Wilayah Bogor
Abstrak: Ostrinia furnacalis Guenée is one of the most important pests of corn in Asia. However, the infestation by this pest in Bogor is low and it is supposed that O. furnacalis population is lowered by natural enemy such parasitoid, predator, or pathogen. This research studied the egg population and biotic factors affecting its development in the field. Observations have been carried out in six villages of six sub-district of Bogor regency. The result showed that six egg clusters have been found in 371 m2 corn field. No differences have been showed by different plant age. Percentage of parasitism by Trichogramma sp. reached 19.90%. While entomopathogenic fungi Fusarium sp. attacked 25.16% egg population. Other minor natural enemy is predatory mite.
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Judul: Penggerek Batang Jagung Ostrinia furnacalis Guenée (Lepidoptera: Crambidae): Tingkat Serangan di Wilayah Bogor dan Siklus Hidupnya di Laboratorium
Abstrak: In Indonesia, corn (Zea mays L.) is used as the second largest food crop after rice. Corn is also important source of animal feed and vegetable oil. The productivity of corn crop often lowered by the infestation of the asiatic corn borer (ACB) Ostrinia furnacalis Guenée (Lepidoptera: Crambidae) and losses due to this pest could reach 20-80%. The purposes of the study are to survey the degree of field infestation by ACB in Bogor area and to investigate the ACB life cycle in the laboratory. Field study was carried out in 15 villages where corn was planted. The presence of the hole and the frass on the corn stalk were observed. Secondary data of agronomy practice were also gathered by interviewing the farmer. Of 75 plant samples that have been determined sistematically on each plot, 52% (the highest) were infested by ACB in village Cikarawang, 6.7% in village Babakan, Neglasari, and Cihideung Udik. No ACB infestation was detected in village Mekarsari. Other villages showed different degree of infestation between 8.3-44%. The different degree of ACB infestation amongst the observed villages did not correlate with the different of plant variety, applied pesticide, and time planting. In the laboratory the ACB eggs hatched in 4 days. By using the artificial diet for larvae, the stadia of instar I was 3-6 days, instar II was 2-5 days, instar III was 2-7 days, instar IV was 2-7 days, instar V was 5-11 days. The ACB took pupal stage during 6-8 days. The longevity of the ACB adult was 9-15 days. The sexual dimorphism was observed: the size of male pupa and adult was smaller than female, the color pattern of front wing of the male was darker than that of female, and the different form of exterior genital sign.
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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