Kajian Eksergi pada Mesin Pendingin Adsorpsi Menggunakan Pasangan Silikagel-Metanol

Sistem pendingin adsorpsi merupakan salah satu dari sistem pendingin yang ramah lingkungan, dimana dalam ope-rasinya sistem ini dapat dibangkitkan menggunakan sumber energi terbarukan seperti biomassa ataupun sinar surya. Sistem pendingin adsorpsi yang digunakan dalam percobaan ini menggunakan pasangan silika gel-metanol sebagai absorben dan refrigeran. Tujuan dari penelitian ini adalah mendapatkan kinerja mesin pendingin adsorpsi intermit- ten pasangan silikagel-metanol dan melakukan analisis eksergi pada mesin pendingin adsorpsi intermitten pasangan silikagel­metanol. Metode penelitian diawali dengan pengujian terhadap kebocoran pada semua komponen di da- lam sistem pendingin adsorpsi dan dilanjutkan dengan pengujian sistem pendingin adsorpsi menggunakan pasangan silikagel­metanol. Suhu tiap komponen yaitu generator, kondensor, evaporator dan pipa­pipa masukan dan keluaran diukur dengan menggunakan termokopel tipe C­C yang dihubungan dengan alat perekam suhu. Sedangkan untuk analisis eksergi diawali dengan perancangan model pada masing­masing komponen dalam sistem pendingin adsorpsi intermitten. Hasil percobaan menunjukkan nilai kehilangan eksergi yang diperoleh untuk tiap proses dalam sistem pendingin adsorpsi. Nilai kerugian eksergi menggambarkan ketidak efektifan proses transfer energi dalam sistem pendinginan adsorpsi. Rincian hasil yang dicapai dari perhitungan dengan analisis eksergi memberikan data pada generator desorpsi kehilangan eksergi (exergy destroy) sebesar 35.33 Watt (90.57 %). Kondensor memberikan nilai sebesar 0.20 Watt (0.51 %). Evaporator memberikan nilai sebesar 0.07 Watt (0.18 %) dan pada generator adsorpsi memberikan nilai sebesar 3.51 %

Effect of temperature on Candida antartica lipase B activity in the kinetic resolution of acebutolol

Thermodynamic studies of free Candida antartica lipase B in kinetic resolution of acebutolol have been carried out to characterize the temperature effects towards enzyme stability and activity. A decreased in reaction rate was observed in temperature above 40oC. Thermodynamic studies on lipase deactivation exhibited a first-order kinetic pattern. The activation and deactivation energies were 39.63 kJ/mol and 54.90 kJ/mol, respectively. The enthalpy and entropy of the lipase deactivation were found to be 52.12 kJ/mol and -0.18 kJ/mol, respectively

Pengaruh Waktu Pengeringan Dan Tempering Terhadap Mutu Beras Pada Pengeringan Gabah Lapisan Tipis

The aim of this research was to determine the effect of various drying and tempering durations on rice quality using thin layer drying. The drying procedure consist four satge; first rough rice was dried in a drying chamber for various durations to remove 5 to 8 % moisture content (M.C). In the second stage rice was tempered under the room temperature for certain duration, to reduce MC gradients within the kernels. tempering period. The rice was then dried further to reach the final 14 % M.C. After the second drying the rice was tempered. Drying process was conducted using  heated air at temperature of either 50 0C, RH 26%  or  60 0C, RH 17%. The results  show that very small  reduction in Head Rice Yield (HRY) when  less than 6 % m.c, were removed during the first drying stage. Effects on HRY was obeserved when the moisture removal was greater than 6% m.c. during the 1st drying stage. It was also observed that tempering time could not prevent the reduction in HRY when moisture remomal was higher than 6% M.C. during the 1st drying stage

Evaluation of Clinical Efficacy of Biodegradable Chip Containing Salvadora persica Extract in Chitosan Base as an Adjunct to Scaling and Root Planning in the Management of Periodontitis

Objective: The objectives of this study were to develop two biodegradable periodontal chips containing Salvadora persica or Benzyl isothiocyanate (BITC) extract and evaluate its clinical effectiveness in managing periodontitis. Methods: Chips were formulated from Salvadora persica, Benzyl isothiocyanate (BITC) and chitosan; twelve patients with periodontal pockets measuring ≥5 mm participated in this study. Overall, 240 periodontal pockets were evaluated. All patients were treated with full mouth scaling and root planning (SRP) at baseline. Periodontal pockets were divided into four groups. One of which is the control group, while group two received plain chitosan chip. Group three received chips containing Salvadora persica extract, and group four received chips containing BITC. Plaque index (PI), bleeding on probing (BOP), periodontal probing pocket (PPD) depth, and clinical attachment levels (CAL) using acrylic stents were recorded at days 0 and 60 only. Results: Data were statistically analysed; Chi-square t-test and an ANOVA were used. Results showed significant improvement in plaque index, bleeding on probing, and reduction in periodontal pocket depth in all four groups (p<0.05). The gain in clinical attachment level was significantly higher (p<0.005) among the group receiving Salvadora persica chips compared to the control and other chip-treated groups. Conclusion: Periodontal chips containing S. persica can be used as adjuncts to treat patients with periodontitis. Keywords: Chitosan; Periodontal chip; Miswak extract; Benzyl isothiocyanate; Periodontitis

Carbonized rice husk and cocopeat as alternative media bed for aquaponic system

The study evaluates the suitability of carbonized rice husk and cocopeat substrates as alternative media bed in aquaponics unit for cultivation of red Nile tilapia and Gynura procumbens. Area occupied by the aquaponics unit is about 4.5 m2 and it was operated under equatorial climate conditions. Various substrates namely lightweight expanded clay aggregate (LECA), cocopeat, carbonized rice husk and a mixture of cocopeat-rice husk at ratio 1:1 were prepared using polybags for growing of the longevity spinach. The resultant effects from fish cultivation and plants growth on the water qualities and nitrification efficiency of the aquaponics unit were reported. The aquaponics unit were operated for twelve weeks and the values of pH, temperature, and dissolved oxygen level were measured to be within the range of 6.4-6.9, 27.7-29oC, and 5.5-7 mg·L-1, respectively. Survival rate for fish was 98% with specific growth rate (SGR) and food conversion ratio (FCR) of 6.9% per day and 1.13, respectively. Nutrient deficiency was not evident and plants showed healthy growth with harvest yield ranging between 3.6 and 3.9 kg·m-2. Results attained signified the suitability of utilizing carbonized rice husk and cocopeat as alternatives media bed compared to commercial media bed such as LECA