Judul: Biogas from a Mixture of Banana Stalks and Chicken  Manure
Abstrak: Usaha peternakan ayam ras petelur menghasilkan kotoran yang dapat mencemari lingkungan jika tidak ditangani dengan baik. Pengolahan kotoran ayam ras petelur perlu dilakukan untuk mengurangi dampak negatif bagi lingkungan. Biogas merupakan teknologi yang dapat menghasilkan sumber bahan bakar alternatif yang dapat diperbaharui karena menggunakan bahan baku yang berasal dari kotoran ternak. Tujuan penelitian ialah menganalisis potensi biogas dari campuran kotoran ayam ras petelur dan batang pisang. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) 3 perlakuan yaitu kontrol (K100B0: 100% kotoran ayam), perlakuan 1 (K70B30: kotoran ayam 70% dan batang pisang 30%) dan perlakuan 2 (K50B50: kotoran ayam 50% dan batang pisang 50%) yang disimpan dalam digester yang berukuran 30 liter selama 35 hari. Parameter yang diamati pada penelitian ini adalah pH, total solid (TS), volatile solid (VS), uji nyala api dan volume gas. Produksi biogas yang diindikasikan oleh TS dan VS awal dan akhir pada perlakuan 1 dan 3 lebih tinggi (P>0,05) daripada kontrol. Nyala api pada perlakuan 1 dan perlakuan 2 lebih lama dan api yang dihasilkan berwarna biru dengan kandungan metana lebih tinggi daripada yang kontrol. Hasil penelitian ini mengindikasikan potensi yang tinggi pemanfaatan kotoran ayam ras petelur dan batang pisang sebagai bahan pembuatan biogas., Layer chicken production produces manure that could be pollute the environment if those are not handled properly. Waste treatment, therefore, need to be done to minimize the negative impact of manure pollution to the environment. Biogas is an alternative technologies to produce a renewable energy by using raw materials derived from livestock manure. This research objective is to analyze the the potency of layer chicken manure and banana stalks as raw material for biogas production. The study used completely randomized design. There were 3 treatments in this study, namely control (K100B0: 100% layer chicken manure), treatment 1 (K70B30: 70% chicken manure and 30% banana stalks), and treatment 2 (K50B50: 50% chicken manure and 50% banana stalks) using a digester with a volume of 30 liter, and incubated for 35 days. Parameter measured in this study were pH, total solid (TS), volatile solid (VS), flame, and gas volume. The treatment groups (K70B30 and K50B50) produced higher (P>0.05) biogas production compared to control group that was indicated by higher initial and final TS and VS content. The methane content and flame produced by treatment groups (K70B30 and K50B50) were longer than the control (K100B0). Those above results show the high potency of layer chicken manure and banan stalks as materials for biogas
Keyword: banana stalks, biogas, layer chicken manure, pH, total solid, volatile solid, flame, gas volume

Judul: Biogas Production from the Combination of Dairy Cow Manure and Layer Chicken Manure
Abstrak: Banyaknya populasi sapi perah dan ayam petelur di Jawa Barat dapat menghasilkan kotoran berlebih. Kotoran sapi perah memiliki C/N ratio dan kadar air yang tinggi dan kotoran ayam petelur memiliki keunggulan nutrisi dan protein yang tinggi. Biogas dapat dihasilkan dari kotoran sapi dan ayam petelur melalui fermentasi anaerobik. Tujuan penelitian adalah menganalisis produksi biogas dari kombinasi kotoran sapi dan ayam. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) dengan tiga level perlakuan dan tiga ulangan. Perlakuan pada penelitian adalah S100A0 (100% kotoran sapi dan 0% kotoran ayam), S80A20 (80% kotoran sapi dan 20% kotoran ayam), dan S60A40 (60% kotoran sapi dan 40% kotoran ayam). Nilai TS awal dan TS akhir setiap perlakuan berbeda nyata (P<0,05). Volume biogas, kandungan metana, dan panjang nyala api bervariasi berdasarkan variasi level perlakuan S100A0 dibandingkan dengan S80A20 dan S60A40. Hasil analisis menunjukkan bahwa jika kotoran sapi dipadukan dengan kotoran ayam dengan takaran S60A40 menghasilkan biogas yang lebih maksimal., The high population of dairy cows and laying hens in West Java can result in excess manure. Dairy cow manure has a high C/N ratio and moisture content, while chicken manure from laying hens has high nutritional and protein advantages. Biogas can be produced from the manure of both dairy cows and laying hens through anaerobic fermentation. The research aims to analyze the biogas production from the combination of dairy cow and chicken manure. This study uses a Completely Randomized Design (CRD) with three treatment levels and three replications. The treatments in the study are S100A0 (100% dairy cow manure and 0% chicken manure), S80A20 (80% dairy cow manure and 20% chicken manure), and S60A40 (60% dairy cow manure and 40% chicken manure). The initial and final TS values of each treatment were significantly different (P <0.05). Biogas volume, methane content, and flame length varied based on the treatment level variations of S100A0 compared to S80A20 and S60A40. The analysis results indicate that when dairy cow manure is combined with chicken manure in the proportion of S60A40, it produces optimal biogas.
Keyword: Kotoran sapi perah, Kotoran ayam petelur, biogas, dairy cow manure, laying hen manure

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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