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"Penggunaan minyak nabati secara langsung sebagai bahan bakar alternatif untuk mesin diesel (biodiesel) masih menimbulkan masalah. Masalah tersebut terutama diakibatkan oleh viskositas minyak nabati yang terlalu tinggi jika dibandingkan dengan petrodiesel, sehingga akan menyebabkan proses pembakaran yang tidak sempurna. Untuk itu, perlu dilakukan proses konversi minyak nabati kedalam bentuk ester (metil ester) melalui reaksi transesterifikas guna menurunkan viskositasnyai.Pada penelitian ini dilakukan proses preparasi biodiesel melalui reaksi antara minyak kelapa sawit dan metanol dengan perbandingan volume 5 : 1, serta menggunakan NaOH sebagai katalis dengan variasi 3,5 gr, 4,5 gr, 5 gr dan 5,5 gr. Reaksi berlangsung pada temperatur 60 oC dan membutuhkan waktu selama + 1 jam. Gliserin yang terbentuk dipisahkan, kemudian hasil produk metil ester (biodiesel) yang diperoleh dicuci dengan air sampai mencapai pH normal (6-7). Semakin besar jumlah katalis yang digunakan dapat menurunkan produk biodiesel yang dihasilkan, yang berarti akan meningkatkan hasil dari produk samping.Hasil pengujian karakteristik yang diperoleh menunjukkan bahwa produk biodiesel dari penggunaan katalis (NaOH) sebanyak 3,5 gram (M3.5), 4,5 gram (M4.5) dan 5 gram (M5.0) lebih memenuhi karakteristik dari minyak diesel (untuk mesin diesel putaran rendah); sedangkan produk biodiesel dari penggunaan katalis 5,5 gram (M5.5) lebih memenuhi karakteristik dari minyak solar. Campuran antara 20 % biodiesel M5.5 dengan 80 % minyak solar (B20) mempunyai karakteristik yang lebih mendekati kondisi optimal yang dibutuhkan oleh bahan bakar mesin diesel.

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Biodiesel's characteristics preparation from palm oil. Using vegetable oils directly as an alternative diesel fuel has presented engine problems. The problems have been attributed to high viscosity of vegetable oil that causes the poor atomization of fuel in the injector system and pruduces uncomplete combustion. Therefore, it is necessary to convert the vegetable oil into ester (metil ester) by tranesterification process to decrease its viscosity.In this research has made biodiesel by reaction of palm oil and methanol using lye (NaOH) as catalyst with operation conditions: constant temperature at 60 oC in atmosferic pressure, palm oil : methanol volume ratio = 5 : 1, amount of NaOH used as catalyst = 3.5 gr, 4.5 gr, 5 gr and 5.5 gr and it takes about one hour time reaction. The ester (metil ester) produced are separated from glycerin and washed until it takes normal pH (6-7) where more amount of catalyst used will decrease the ester (biodiesel) produced.The results show that biodiesels properties made by using 3.5 (M3.5) gr, 4.5 gr (M4.5) and 5 (M5.0) gr catalyst close to industrial diesel oil and the other (M5.5) closes to automotive diesel oil, while blending diesel oil with 20 % biodiesel (B20) is able to improve the diesel engine performances."

"ABSTRAKPenelitian ini termasuk dalam true experiment yang bertujuan untuk menguji main effect maupun interaction effect variabel mental accounting dan self efficacy terhadap pengambilan keputusan investasi mesin produksi. Metode yang digunakan adalah true experiment, dengan desain 2 x 2 between subject yang menggunakan dua level kondisi mental accounting (ada atau tidak ada) dan dua level kondisi self efficacy (tinggi atau rendah). Uji statistik yang digunakan dengan Analysis of Variance (ANOVA), untuk hipotesis pertama dan kedua menggunakan One Way Analysis of Variance dan untuk hipotesis ketiga menggunakan Two Way Analysis of Variance. Hasil penelitian menemukan bahwa mental accounting terbukti berpengaruh terhadap pengambilan keputusan investasi mesin produksi. Self efficacy juga terbukti berpengaruh terhadap pengambilan keputusan investasi mesin produksi. Sementara efek interaksi antara mental accounting dan self efficacy tidak berpengaruh terhadap pengambilan keputusan investasi mesin produksi.

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ABSTRACT

This research is included in the true experiment which aims to test the main effect and the interaction effect of mental accounting and self efficacy on investment decisions on production machinery. The method used is the true experiment, with the design of 2 x 2 between subjects that uses two levels of mental accounting (existing or absent) and two levels of self efficacy (high or low). Statistical tests are used with ANOVA, for the first and second hypotheses using One Way Analysis of Variance and for the third hypothesis using Two Way Analysis of Variance. The results of the study found that mental accounting proved to influence the investment decision making of production machinery. Self efficacy is also proven to have an effect on investment decisions in production machinery. While the interaction effect between mental accounting and self efficacy does not affect the investment decision making of a production machine."

"Untuk mengetahui perbandingan struktur komunitas fitoplankton di perairan Situ Rawa Besar (luas 17 ha) dan Situ Rawa Kaiong (luas 8,23 ha) Kabupaten Bogor, Jawa Barat, telah dilakukan penelitian bersifat deskriptif analitik pada buian Mei-Juni 1998. Pengambilan sampel di setiap stasiun dilakukan secara horizontal dan vertikai, diikuti pengukuran kuaiitas air yaitu: suhu, kecerahan, pH, DO, dan BOD5. Hasil penelitian diperoleh 73 marga fitoplankton di Situ Rawa Besar terdiri dari Cyanophyta (11 marga), Chrysophyta (19 marga), Chlorophyta (39 marga), Dinophyta (1 marga), dan Euglenophyta (3 marga). Di Situ Rawa Kaiong diperoleh 33 marga terdiri dari Cyanophyta (6 marga), Chrysophyta (13 marga), Chlorophyta (11 marga), Dinophyta (1 marga), #■ Charophyta (1 marga), dan Euglenophyta (1 marga). Jumlah individu fitoplankton di Situ Rawa Besar dan Situ Rawa Kaiong yaitu: 45.419 ind/l dan 187.916 ind/l, indeks keanekaragaman dan indeks kemerataan di Situ Rawa Besar dan Situ Rawa Kaiong yaitu: 1,60; 0,37 dan 0,55; 0,16 serta indeks kesamaan kedua situ sebesar 43,4%. Hasil pengukuran kuaiitas air di Situ Rawa Besar meliputi suhu, kecerahan, pH, DO, dan BOD5 masing-masing berkisar 29--33''C; 14-27 cm; 6-8; 1,3-6 ppm dan 2,6-4,47 ppm. Hasil pengukuran kuaiitas air di Situ Rawa Kaiong meliputi suhu, kecerahan, pH, DO, dan BOD5 masing-masing 29-34°C; 16,5-29 cm; 6-10; 1-8 ppm, 4,17-6,98 ppm. Hasil penelitian dapat disimpulkan jumlah marga di Situ Rawa Besar lebih besar dibandingkan Situ Rawa Kaiong, tetapi kepadatannya lebih kecil dibandingkan dengan Situ Rawa Kaiong. Marga yang mendominasi kedua situ dari Divisi cyanophyta yaliu Microcystis. Indaks kaanakaragaman tartinggi dan terandah tardapat di Situ Rawa Basar (1,60) dan Situ Rawa Kalong (0,55). Kaanakaragaman di kadua situ barbada nyata. Indaks kamarataan tartinggi dan tarandah tardapat di Situ Rawa Basar (0,37) dan Situ Rawa Kalong (0,16). Indaks kasamaan di kadua situ sadang (43,4%)."

"The aim of this research is to see the effect of various dentin conditioners (phosphoric acid) to the bond strength between resin adhesive HNPM/TEGDMA (2 Hydroxy-3,2-Napthoxy-Propyl Methacrylate/Trietilen Glikol di Methacrylate) and dentin tissue of bovine teeth. Dentin conditioner that was used are phosphoric acid solution 10%, 25%, 35% (Group A1, A2, A3). Specimens was divided into 3 Groups, each group has 10 specimens. Bond strength test used "Universal Testing Machine". A G 5000 and SHIMADZU type. The result of this research shows average differences of bond strength of each group. Anova test there is a significant difference (8.485 and p < 0,05). Double comparison Tukey test among groups generally are significant different (p<0,05) except between A2 and A3 group. The result of the research states there are effects of various dentin conditioners to the bond strength between resin adhesive NHPM/TEGDMA and dentin tissue."

"Background: pathophysiology of functional dyspepsia remains poorly understood. Many factors such as gastric motility disorder, visceral hypersensitivity, Helicobacter pylori (Hp) infection, psychological stress and excessive gastric acid secretion play roles in this symptom. Psychological stress may promote peptic ulcer and has an effect on ulcers-associated Hp. This study aimed to determine Helicobacter pylori activity and expression of mucosal IL 6 and their association with psychological stress. Methods: a cross-sectional study was done among 40 outpatients with dyspeptic syndromes in M. Djamil General Hospital and two community health centers in Padang. The subjects were divided into two groups, with and without psychological stress, which were identified using DASS 42. Gastric biopsy specimens and peripheral blood samples were taken while performing esophagogastroduodenoscopy. Immunohistochemistry methods was used to determine the expression of IL 6 and Hp in gastric mucosa. The correlation of each variable in the group experiencing psychological stress and non stress was analyzed using Chi square test. Results: there were 40 patients with functional dyspepsia with average age of 37.58(SD 11.82) years old. The cortisol levels were significantly different between both groups (non stress vs. stress groups); moreover, morning cortisol level in psychological stress group was higher beyond normal limit. Interleukin 6 expression, as the evidence of inflammatory activity, seemed higher in non stress group than the group with psychological stress (8.25% vs. 7.25%). Helicobacter pylori activity was seemed to be increased in the stress group as characterized by higher numbers of invasion to the sub mucosa epithelium compared to the non stress group (11 vs. 7 subjects). Conclusion: psychological stress seems to have no correlation with IL-6 in gastric mucous of patients with functional dyspepsia; however, there is an evidence of increasing activity of Helicobacter pylori."