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"Based on previous studies ,nitrogen injection could recover oil up to 45-90 % of initial reserves...."

"Characterizations have been performed on single stage Transversely Excited Nitrogen Laser of Blumlein type. Optical cavity arrangement is varied prior to measurement which shows no significant increase in energy on both configurations of inserting a mirror only and a pair of mirror and a quartz parallel plate. Frequency repetitions respond reveals a small drop in energy at higher frequency i.e. 10 Hz by a factor of 20%. N2 flow rate consideration behaves on the similar way like pressure profile. At higher supply voltage maximum energy is shifted to higher N2 flow rate. A similar tendency occurs on pressure curve but with more pronounced maximum energy. Higher supply voltage would shift maximum energy to higher N2 pressure. Other operating conditions have been kept constant. Beam divergence measurement has given 1,87 mrad on vertical direction and 9,32 mrad on horizontal axis. However, beam cross section experiences a -10° tilt against horizontal reference. This may happen due to a slight twist on main electrodes. Measurements on different date have showed inconsistent results. Major cause is suspected on using different N2 cylinder, replacement on the gauge pressure, and crater creation on HV side spark gap electrode."

"ABSTRACTTwo laboratory-scale sequencing batch reactors (SBR) arranged in series were used to evaluate bioxidadon and nitrogen removal from a synthetic sewage consisting of acetic acid as the carbon source. Microprocessor based timer were used to control various phases in the SBR?s phases. This paper discusses the result of varying recycle ratio, returned mixed liquor, in bioxidation, denitrification and nitrification process in the modified SBR Generally, as the recycle ratio increased if was found to give a better the removal efficiency in terms of organic carbon and total nitrogen removal. The modified SBR, in general. shows promise as an effective treatment alternative to the conventional activated sludge process."

"Kebakaran lahan gambut terjadi secara berulang di Indonesia. Berbagai penelitian telah dilakukan untuk menemukan metode pemadaman kebakaran membara gambut yang paling efisien. Penelitian ini berfokus pada supresi gambut yang mengalami kebakaran membara dengan metode injeksi busa dalam skala laboratorium. Eksperimen dilakukan untuk mengetahui efektivitas supresi dengan metode injeksi busa pada hotspot gambut dengan variasi sampel yang berbeda, antara lain sampel dari daerah Palangkaraya, Kalimantan Tengah, pada koordinat 2°17'21.9"S 114°01'57.3"E dan Kabupaten Tanjung Timur, Jambi pada koordinat 01°14'11.227"S 103°35'4.851"E. Sementara busa yang digunakan adalah busa dengan konsentrasi larutan 1 %. Pada proses eksperimen, sampel gambut akan dituangkan ke dalam reaktor dengan ukuran 200 mm x 200 mm x 100 mm yang dindingnya dilapisi isolator calcium silicate board dan dilengkapi coil heater yang dipanaskan selama 60 menit dengan daya 100 W. Temperatur kedalaman, massa, dan temperatur permukaan sampel masing-masing diukur dengan termokopel, load cell, dan kamera termal. Proses injeksi busa dilakukan saat termokopel pada kedalaman terbawah mengalami mencapai temperatur minimal 215°C atau mengalami kebakaran membara. Busa diinjeksi menggunakan jarum injeksi yang ditancapkan di tengah reaktor dengan kedalaman 100 mm dari permukaan reaktor. Jarum terhubung dengan alat injeksi terintegrasi dengan kecepatan aliran busa 100 ml/min. Hasil penelitian menunjukkan busa secara efektif dapat mensupresi gambut pada variasi sampel yang berbeda.

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Peatland fires occur repeatedly in Indonesia. Various studies have been conducted to find the most efficient method of extinguishing peat smoldering fires. This research focuses on extinguishing peat smoldering fires by foam injection method on a laboratory scale. Experiments were conducted to determine the effectiveness of suppression by the foam injection method on peat hotspots with different sample variations, including samples from the Palangkaraya area, Central Kalimantan, at coordinates 2°17'21.9"S 114°01'57.3"E and Tanjung Timur Regency, Jambi at coordinates 01°14'11.227"S 103°35'4.851"E. While the foam used was foam with a solution concentration of 1%. In the experimental process, peat samples will be poured into a reactor with a size of 200 mm x 200 mm x 100 mm whose walls are covered with a calcium silicate board insulator and equipped with a coil heater heated for 60 minutes with a power of 100 W. Depth temperature, mass, and surface temperature of the sample are each measured by a thermocouple, load cell, and thermal camera. The foam injection process is carried out when the thermocouple at the bottom depth reaches a temperature of at least 215 °C or undergoes smouldering. The foam is injected using an injection needle stuck in the center of the reactor with a depth of 100 mm from the surface of the reactor. The needle is connected with an integrated injection device with a foam flow speed of 100 ml / min. The results showed that foam can effectively suppress peat at different sample variations."

"ABSTRACTThe autofluorescence spectra of human tissues excited with 33'7,1-nm line of pulse nitrogen laser have been measured. The autofluorescence spectra of cancerous tissues consistently exhibit characteristic peaks near E530-nm and 690-nm. which do not appear in the spectra of the corresponding normal tissues. Spectroscopic investigation indicates that the porphyrin compounds localized and retained in cancerous tissues might be responsible for this characteristic autofluorescence. This preliminary result suggests the possibility of employing spectroscopy tool for complementary diagnosis of cancer along with the traditional methods of pathological analysis."

"ABSTRAKPrinsip pemurnian sulfur dari batuan sulfur alam salah satunya adalah dilakukan dengan pemanasan menggunakan Proses Frasch. Hal ini karena titik leleh sulfur (119,6 oC) yang tergolong reatif rendah. Proses ini memerlukan injeksi steam berlebih kedalam batuan sulfur alam untuk melelehkan kandungan sulfur dan memisahkan dari pengotornya. Pada penelitian ini dilakukan proses permunian sulfur dari batuan sulfur alam dalam sistem batch dengan steam autoclave agar proses lebih cepat dan dapat dijalankan dalam skala lab. Penelitian terakhir menggunakan steam autoclave menunjukan yield sulfur hasil pemurnian masih belum maksimal, yaitu hanya 72% dari massa batuan sulfur awal pada kondisi optimumnya dan 80% pada kondisi maksimalnya. Oleh karena itu, pada penelitian ini selain menggunakan steam juga dilakukan preinjeksi gas nitrogen kedalam sistem. Gas nitrogen meningkatkan jumlah media yang mentransfer panas pada sistem sehingga terjadi peningkatan transfer panas dan juga sebagai medium pre-heating sehingga batuan sulfur akan mengalami peningkatan suhu sebelum dilelehkan dengan media transfer panas steam. Kondisi operasi dengan suhu 140oC, tekanan gas nitrogen 30 psi, rasio air-batuan 10 ml/gr, dan waktu operasi 4-5 menit menunjukkan hasil terbaik dengan yield 82-84,67% dengan kemurnian 99,86-99,94%.

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ABSTRACTOne of method in sulfur purification process from native sulfur is Frasch Process that using heat treatment principle. It can be done caused by the melting point of sulfur that low enough, about 119,6oC. This process needs injection of superheated steam continuously into the deposit of sulfur at the underground. The sulfur will melt due to the melting point and separate from the residues. There has been a research about batch sulfur purification from the natural sufur ore by using steam autoclave, but the yield of the process is still not efficient enough. Therefore, at this research using pre-injection of nitrogen as additional and pre-heating medium in order to enhance the yield. The operation of sulfur purification process at 140oC, nitrogen pressure 30 psi, ratio 10 ml/gr, and 4-5 minutes time operation has shown the best result with yield 82-84,67% and concentration of sulfur 99,86-99,94%."

"Tingginya permintaan pengujian kualitas air permukaan di laboratorium komersil menyebabkan adanya antrian. Dengan adanya antrian, maka sampel yang diserahkan memiliki kemungkinan tidak langsung diuji sehingga sampel akan mengalami fase yang dinamakan fase waktu tunggu. Penelitian ini bertujuan untuk menganalisis perubahan nilai konsentrasi nitrogen selama rentang waktu tunggu. Selain itu, penelitian ini bertujuan menentukan laju perubahan selama proses nitrifikasi berdasarkan nilai perubahan konsentrasi yang terjadi. Kemudian penelitian ini bertujuan untuk memperkirakan nilai konsentrasi awal dari setiap parameter yang ada di dalam proses nitrifikasi. Adapun metode yang digunakan untuk mengetahui perubahan nilai konsentrasi nitrogen selama waktu tunggu adalah dengan melakukan pengujian laboratorium berdasarkan HACH. Sedangkan penentuan laju perubahan yang terjadi dilakukan dengan menggunakan metode Solver. Analisis perkiraan nilai konsentrasi awal dilakukan dengan pemodelan yang menggunakan solusi persamaan ODE Linear faktor pengintegrasian. Hasil pengujian laboratorium menunjukan adanya perubahan nilai konsentrasi amonia, nitrit, dan nitrat dari sampel yang didiamkan selama rentang waktu 14 hari dengan kondisi tanpa diawetkan dan dengan diawetkan. Rentang persentase perubahan nilai konsentrasi yang terjadi adalah sebesar 0,4% - 100% untuk amonia, 7% - 300% untuk nitrit, dan 18,2% - 960% untuk nitrat. Nilai laju perubahan amonia secara berurutan adalah 0,74/hari dan 0,4/hari untuk sampel tanpa pengawetan dan dengan pengawetan sedangkan nitrit adalah sebesar 0,05/hari dan 0,08/hari. Nilai error terkecil ada pada hari kedua untuk meperkirakan konsentrasi awal. Nilai konsentrasi amonia, nitrit, dan nitrat dengan kondisi tanpa pengawetan dan dengan pengawetan secara berurutan dengan menggunakan hari kedua sebagai waktu acuan adalah 17,29 dan 13,17 mg/L, 2,84 dan 15,26 mg/L, 0,93 dan 1,46 mg/L

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The high demand for surface water quality testing in commercial laboratories causes queues. With the existence of a queue, the samples submitted have the possibility of not being directly tested so that the sample will experience a phase called the holding time phase. This study aims to analyze changes in the value of nitrogen concentrations during the waiting period. In addition, this study tries to determine the level of change during the nitrification process based on the value of the changes in concentration that occur. Then this study aims to develop the concentration of the initial value of each parameter in the nitrification process. The method used to determine changes in the value of nitrogen concentration during the holding time is by conducting laboratory tests based on HACH. While the rate of change that occurs is done using the Solver method. Analysis of the estimated value of the initial concentration was carried out by modeling using the solution of the Linear integrating factor ODE equation. The results of laboratory tests showed that there was a change in the concentration values of ammonia, nitrite, and nitrate from the samples which were left for a period of 14 days with unpreserved and preserved conditions. The proportion of change in concentration value that occured is 0,4% - 100% for ammonia, 7% - 300% for nitrite, and 18,2% - 960% for nitrate. The value of the rate of change of ammonia respectively is 0,74/day and 0,4/day for samples without preservation and with preservation while for nitrite is 0,05/day and 0.08/day. Most of the smallest error value exist on the second day to estimate the initial concentration. The concentration values of ammonia, nitrite and nitrate under the condition of unpreserved and preserved respectively using the second day as a time reference were 17,29 and 13,17 mg/L, 2,84 and 15,26 mg/L, 0,93 and 1,46 mg/L."

"Nitrogen is one of the most important minerals for living organisms. Azolla is known as a small water fern which can fix nitrogen through the symbiotic association with the blue green algae Anabaena. Experimental studies were carried out in the glass house, investigating the growth of Azolla us ing different levels of nitrogen and phosphorus in the media. The experiment used 12 treatments with 3 levels of nitrogen (0, 5, and 10 mg atom/L) and 4 levels of hosphorus (0, 10, 20, and 30 mg atom/l) in a factorial design with 3 replicates. The results show that the highest biomass for fresh weight (13.28 g), dry weight (1,126 g), and the fastest doubling time (7.71 days) were found in combination of 10 mg atom/L N and 30 mg atom/L P. Meanwhile, the highest protein content was found in combination of 5 mg atom/L N and 20 mg atom/L P. After the third day heterocyst cells in Anabaena could only be found in those two combinations, but thehighest heterocyst cells was found in the lower N and P combination similar to the highest protein content. Further experiment is suggested to introduce Azolla as bio-fertilizer for acid water system, such as peat land water."