Judul: Rekayasa Pengaturan Udara Berdasarkan Perubahan Kandungan Metana pada Biogas Umpan ke Motor Bakar Bensin
Abstrak: Pembakaran metana dengan jumlah udara yang tidak sesuai mengakibatkan konversi energi kimia ke mekanik pada motor bakar tidak optimum. Sementara itu, kandungan metana di dalam biogas umumnya beragam sehingga diperlukan rekayasa pengaturan udara agar pembakaran menjadi sempurna. Hasil pengukuran kinerja motor bakar dengan perlakuan yang dilakukan menunjukkan daya tertinggi 4.086 kW terjadi pada biogas dengan kandungan metana 92 % di putaran 3000 rpm dan nilai daya terendah adalah 3.236 kW pada biogas dengan kandungan metana 57 % di putaran 3000 rpm. Penggunaan bahan bakar paling hemat terjadi pada kandungan metana 92 % sedangkan penggunaan bahan bakar yang boros terjadi pada kandungan metana 57 %. Berdasarkan perhitungan stoikiometri kandungan 57 %, 62 %, 77%, 82% dan 92 % berturut-turut memiliki air fuel ratio 1: 13.54, 1: 13.97, 1: 15.26, 1: 15.69, 1: 16.55. Efisiensi termal paling tinggi terdapat pada power maksimum pada masing masing bahan bakar, nilai dari efisiensi termal mendekati efisiensi termal dari motor bakar bensin yaitu 25 %.
Keyword: biogas, amda, metana, motor bakar, power

Judul: Penerapan Bahan Bakar Biogas pada Motor Bensin dengan Modifikasi Karburator dan Variasi Rasio Kompresi
Abstrak: Biogas is one of the gaseous bio-energy can be applied into gasoline motors with some modification of components. The objectives of this research are applying the biogas fuel in gasoline engine with carburetor modification, measuring and getting value of maximum power and maximum torque and minimum value of the specific fuel consumption of each variation of compression ratio. The results of research were the biogas fuel on gasoline motors could be implemented directly, carburetor modifications changed the ratio of air and fuel ratio of 14.7: 1 (gasoline) to 5.7:1 (biogas) as of gasoline engine could be operated with engine speed over 1500 rpm up to 4500 rpm in a stable condition. The maximal power values for each compression ratio were 0.827 kW at compression ratio (CR 7.6), 0.953 kW (CR 8.3), 0.838 kW (CR 9.0) and 0.764 kW (CR 10.0). Maximum torque values were 3.071 N.m at compression ratio (CR 7.6), 4.274 N.m (CR 8.3), 3.598 N.m (CR 9.0), and 4.074 N.m (CR 10.0). The results of lowest value of specific fuel consumption were 4.29 m3/kWh at compression ratio (CR 7.6), 2:13 m3/kWh (CR 8.3), 1.84 m3/kWh (CR 9.0), and 2.92 m3/kWh (CR 10.0). The optimal of compression ratio was 8.3.
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Judul: Systematics of Desmos (Annonaceae) in Malesia
Abstrak: Desmos is a woody climbing genus of Annonaceae which has been widely used as traditional medicine in several countries such as China, Indo-China, Thailand, and Peninsular Malaysia to treat dysentery, vertigo, fever, and postpartum. Phylogenetic studies on Desmos showed a close relationship between Desmos and Dasymaschalon. They share similar moniliform monocarpic fruits, but their flowers are different. It has been debated among Annonaceae researchers whether both genera should be treated as the same or distinct genus. Therefore, investigation on the taxonomic delimitation of Desmos species and Dasymaschalon will be necessary. Plastid genome (plastome) identification, leaf epidermal section of Desmos species and Dasymaschalon species, a taxonomic revision of Desmos in Malesia using morphological data, the spatial distribution of Desmos species in Malesia, and morphological and genetic variation in Desmos chinensis population using ISSR marker were used to investigate taxonomic delimitation of Desmos. Plastome study of Desmos chinensis and Dasymaschalon dasymaschalum was carried out to determine the origin, evolution, phylogenomics, and identify marker candidates for Desmos and Dasymaschalon or with other genera in Annonaceae. We discovered that the plastome of Desmos chinensis was circular with the size of 167,677 bp (smaller than Dasymaschalon dasymaschalum), consist of 111 genes, including 78 protein-coding genes, 29 transfer RNAs, and 4 ribosomal RNAs. The plastome showed a typical quadripartite structure, i.e., large single copy (LSC), small single copy (SSC), and two inverted repeats (IRs). The plastome of Dasymaschalon dasymaschalum was 191,488 bp in length, which also exhibited a typical quadripartite structure (LSC, SSC, and two IRs). Desmos chinensis and Dasymaschalon dasymaschalum showed different copies of accD, ndhD, ndhF, rps18, and ycf2. Protein coding genes of rpoB, rpoC1, rbcL, matK, rpl32, infA, and rpl36 were identified based on nucleotide diversity, sequence variability, and parsimony-informative sites. The genes are defined as molecular marker candidates of plastome for phylogenetic, barcoding, and population genetic research. We predicted that Desmos chinensis and Dasymaschalon dasymaschalum separated at ca. 64 million years ago during the Paleocene. Leaf anatomical feature study was carried to support the taxonomic delimitation of interspecific Desmos and intergeneric of Desmos and Dasymaschalon. Leaf anatomy in the paradermal section of 20 taxa (12 species of Desmos, eight species of Dasymaschalon) have been carried out. According to the leaf epidermal section, Desmos and Dasymaschalon are two distinct genera mainly distinguished based on the anticlinal wall undulation of epidermal cells and supported by variation of the crystal type and size. The anticlinal wall undulation of Desmos was almost straight to slightly wavy and never sinuous; meanwhile, Dasymaschalon varies from almost straight to deeply sinusoid. The crystals of Desmos consist of rhombohedral, druse type A, and druse type B crystals, whereas Dasymaschalon has prism, druse type A, druse type B, and druse type C crystals. The recent taxonomic revision using the morphological data was mainly based on the examination of about 1374 specimens from BO, L, WAN, ANDA, SING, SAN, K, P, HUH herbaria. The Desmos species in Malesia consists of eight species: D. acutus, D. chinensis, D. chryseus, D. dunalii, D. pedunculosus, D. subbiglandulosus, two new records: D. lawii and D. macrocarpus, and one
Keyword: Dasymaschalon, Desmoid clade, Magnoliid, plastid genome, phylogenomics analysis