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INDONESIA
SAINS DAN MATEMATIKA
Published by Universitas Diponegoro
ISSN : -     EISSN : -     DOI : -
Core Subject : Education,
Mathematics
Arjuna Subject : -
Articles 5 Documents
 1 
Search results for , issue "Volume 23 Issue 2 Year 2015" : 5 Documents clear
Synthesis of Carboxyl (CNT-COOH) and Ammine Carbon Nanotubes (CNT-NH2) Pardoyo, Pardoyo; Suharini, Sri Eny; Nandiyah, Siti; Subagio, Agus
JURNAL SAINS DAN MATEMATIKA Volume 23 Issue 2 Year 2015
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

A research synthesizing CNT-COOH to increase the compatibility character of carbon nanotubes and CNT-NH2 to increase the hydrophilic character has been done. The CNT-COOH was synthesized using ultrasonic bath method for 6 hours with the volume ratio of concentrated H2SO4 : HNO3 were 2:1, 3:1 and 4:1. Whereas CNT-NH2 was produced by refluxing CNT and ethylene diamine at temperature of 40°C, 60°C and 80°C. Both products were analyzed with Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The C=O bond on CNT-COOH was showed by wavenumber of 1635.64 cm-1 and the OH bond at 3448.72 cm-1 whilst the N-H bond emerged at 152762 cm-1. SEM and EDS indicated both products had surface morphology of tubes and reducing of Fe content which was the one of impurities of CNT.
Gamma Spectroscopy Response Analysis of Bismuth Germanium Oxide (BGO) and NaI (Tl) Detector to Determine the Detector Efficiency using the Monte Carlo MCNPX Method Oktajianto, Hammam; Setiawati, Evi; Richardina, Verry
JURNAL SAINS DAN MATEMATIKA Volume 23 Issue 2 Year 2015
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

Simulation of Gamma spectroscopy with Bismuth Germinate Oxide (BGO) and NaI(Tl) detectors has been done using Monte Carlo method in MCNPX computer program. Simulation was conducted by modelling detector scintillator geometry, model of radiation source which was Cobalt-60 and pulse count model. BGO and NaI(Tl) had a diameter of 3 inch and thickness of 3 inch and closed by Aluminium with 0.05 cm thickness. Extended radiation source of Cobalt-60 was in radius of 0.15 cm which was put in front of detector surface with distance of 0.001 cm, 2 cm, 4 cm, and 12 cm. The simulation results showed that the less radiation count with increasing distance of the radiation source which was put in front of detector. Reduce of the radiation count lead to decrease efficiency in each increase of radiation source distance. The detector efficiency to count gamma ray radiation of BGO detectors was better than NaI(Tl) detector. The maximum efficiency of both detectors was occurred at distance of 0.001 cm in front of detector. These results also showed that MCNPX was able to agreeably simulate detector process to determine spectroscopy Gamma response.
Whey Tahu sebagai Penghasil Biolektrisitas pada Sistem Microbial Fuel Cell dengan Lactobacillus Plantarum Ismawati, Nur; Aminin, Agustina L. N.; Suyati, Linda
JURNAL SAINS DAN MATEMATIKA Volume 23 Issue 2 Year 2015
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

Bioelectricity of soy whey in Microbial Fuel Cell system with Lactobacillus plantarum has been performed. This study aims to determine the capacity of soy whey as a substrate in the MFC system and determine the influence of the speed of agitation against potential difference generated. The potential difference compared to different substrates, namely soy whey, glucose and lactose. Determination of the potential difference in speed variation agitation performed with variations 30, 60, 90, 125 and 250 rpm. The potential difference at the maximum voltage variation of the substrate obtained by soy whey by 33.3 mV / 100 mL at the 15th hour, whereas glucose and lactose reaches the maximum potential difference at the 12th hour with a relatively similar value. Agitation speed that generates the highest potential difference in soy whey substrate was obtained at 90 rpm with maximum potential difference of 63.1 mV / 100mL at the 14th hour.
The Antioxidant Activities, Phenolic Total and Cytotoxicity of Extract and Fractions of Aloe Vera Linn) Prahesti, Nike Rizky; Suzery, Meiny; Cahyono, Bambang
JURNAL SAINS DAN MATEMATIKA Volume 23 Issue 2 Year 2015
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

Aloe vera is known containing compounds which have potencies as antioxidants, such as group of anthraquinones (especially emodin and aloin), flavonoids, tannins, saponins, and sterols. In this research, comparison of total phenolics content, antioxidant activity and cytotoxicity of the methanolic extract and its fractions had been conducted. The Aloe vera extract was fractionated using a solvent gradient system to obtain fractions of n-hexane, dichloromethane, ethyl acetate and water. The analysis of total phenolic and activity were performed on extracts or fractions that showed a positive result to the phenolic test. Total phenolic content was determined by the Folin - Ciocalteu method, determination of antioxidant activity was by DPPH radical reduction and determination of cytotoxicity was by BSLT (Brine Shrimp Lethality Test). The results showed that the yield of methanol extract, fractions n-hexane, fraction of dichloromethane, ethyl acetate and water fraction were 0.580% ; 0.006% ; 0.093% ; 0.0092% and 0.410% respectively. Methanolic extract, ethyl acetate fraction and the water fraction showed positive result on phenolic test. Total phenolic compounds from water fractions was (16. mg gallic acid equivalent/g extract or fraction) which had greater level than Emet and Fea (12.47 and 0.89). Fraction of water had the highest antioxidant activity (IC50 433 mg/L) compared to Emet (IC50 519.23 mg/L) and Fea (IC50 1311.36 mg/L). All of three samples had cytotoxic potency, water fraction (Fair) was the most active sample (LC50 5.209 ppm) compared to Emet (LC50 18.383 ppm) and Fea (LC50 56.486 ppm). Overall it can be proposed that the water fraction is the most active fraction compared to the other fractions or extracts.
Isolation and Identification of Mold Contaminants on Mushroom Growing Medium (Bag Log) and Their Cellulolytic Performance Test Handayani, Tatik; Purwantisari, Susiana
JURNAL SAINS DAN MATEMATIKA Volume 23 Issue 2 Year 2015
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

Mushrooms naturally grows on logs that have experienced weathering. Raw materials of mushroom growth media containing plenty of wild microbes, especially wild mold on sawdust media. Sterilization conducted did not prevent the occurrence of contamination. This study aim was to determine the types of contaminant molds in cultivated mushroom growth media (bag logs), as well as determine their cellulolytic performance. Mushroom growth media (bag log) samples were taken from three mushroom cultivation locations. Mold isolates obtained were identified by their macroscopic and microscopic characteristics. Test the mold cellulolytic performance was conducted by measuring the ratio of hydrolysis zone with the diameter of mold on CMC (Carboxy Methyl Cellullose) media. The isolation and identification results of contaminant molds consisted of mold isolates which could be grouped into 7 genus which were Aspergillus, Penicillium, Paecillomyces, Trichoderma, Rhizopus, Fusarium and Syncephalastrum. The cellulolytic performances of mold on CMC media showed that Aspergillus flavus has the greatest cellulolytic ability.

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