Environmental effects on the stable carbon and oxygen isotopic compositions and skeletal density banding pattern of Porites coral from Khang Khao Island, Thailand

The timing of band formation and linear skeletal growth rate based on environmental changes were investigated using alizarin red S (ARS) in Porites lutea coral at Khang Khao Island, the Gulf of Thailand from November 10, 1999 to March 15, 2001. The X-radiograph of the vertical section of the Porites coral skeleton was examined and three pairs of density bandings including intermediate bandings were observed in one year, suggesting that additional factors other than sea surface temperature (SST) were associated during the process of band formation. We assumed that variation of salinity variations, nutrition/sedimentation load and light intensity may control the process of density band formation which may be influenced by the river run-off due to heavy rainfall. The coral skeleton was analyzed and measured from top to a depth of 47 mm by mass spectrometry and three cyclic changes in both oxygen and carbon isotopic values which reveal the abrupt changes of aquatic environment was observed. By using isotopic compositions, X-radiography and analyzing ARS line, the average annual growth rate of the Porites coral was inferred at ~17.91 mm/year. Our results demonstrate that the density bands of coral and perhaps a useful proxy of extension rate could also be a potential indicator for reconstructing the past SSTs in rain-infested areas like the upper Gulf of Thailand.Keywords: Oxygen isotopes, carbon isotopes, Porites coral, density bands, skeletal growth, sea surface temperature, salinity, Khang Khao, Gulf of ThailandAfrican Journal of Biotechnology Vol. 9(33), pp. 5373-5382, 16 August, 201

Prospek Model Daur Belajar 5 Fase terhadap Keterampilan Proses Sains dan Kemampuan Berpikir Kritis Siswa pada Materi Termokimia

Materi termokimia mencakup konsep-konsep yang bersifat abstrak, algoritmik, dan saling berhubungan satu sama lain sehingga siswa mengalami kesulitan dalam memahaminya. Selain itu, proses pembelajaran kimia selama ini cenderung menggunakan model pembelajaran konvensional. Model pembelajaran ini lebih menekankan pada hasil belajar kognitif, namun tidak memperhatikan aktifitas keterampilan proses sains dan kurang melatih kemampuan berpikir kritis siswa. Dengan demikian, diperlukan model pembelajaran yang mampu meningkatkan keterampilan proses sains dan kemampuan berpikir kritis siswa yaitu menggunakan model daur belajar 5 fase. Kajian ini bersifat deskriptif dan berbasis literatur yang bertujuan untuk mengetahui prospek model daur belajar 5 fase terhadap keterampilan proses sains dan kemampuan berpikir kritis siswa

Surface Behavior of Rhodamin and Tartrazine on Silica-Cellulose Sol-Gel Surfaces by Thin Layer Elution

Physical and chemical interactions are the principles for different types of separation systems as the equillibrium dynamics on surface plays a key-role. Surface modification is a way for selective separation at interfaces. Moreover, synthesis of gel silica by a sol-gel method is preferred due to the homogeneity and surface feature easily controlled. Cellulose can be added in situ to modified the silica features during the process. Further application for to study interaction of rhodamin and tartrazine in its surface and their solubilities in mobile phase explains the possibility for their separation. This paper devoted to evaluate the surface behavior in term of adsorption and desorption of tartrazine and rhodamin on silica-cellulose thin layer in different mobile phase. Some carrier liquids applied such as methanol, acetone, n-hexane and chloroform. The result proves tartrazine and rhodamin is separated and have different behavior in different mobile phase. The retardation factors (Rf) of the mixtures suggest complexity behavior on silica-cellulose surface

Surface Behavior of Rhodamin and Tartrazine on Silica-Cellulose Sol-Gel Surfaces by Thin Layer Elution

Physical and chemical interactions are the principles for different types of separation systems as the equillibrium dynamics on surface plays a key-role. Surface modification is a way for selective separation at interfaces. Moreover, synthesis of gel silica by a sol-gel method is preferred due to the homogeneity and surface feature easily controlled. Cellulose can be added in situ to modified the silica features during the process. Further application for to study interaction of rhodamin and tartrazine in its surface and their solubilities in mobile phase explains the possibility for their separation. This paper devoted to evaluate the surface behavior in term of adsorption and desorption of tartrazine and rhodamin on silica-cellulose thin layer in different mobile phase. Some carrier liquids applied such as methanol, acetone, n-hexane and chloroform. The result proves tartrazine and rhodamin is separated and have different behavior in different mobile phase. The retardation factors (Rf) of the mixtures suggest complexity behavior on silica-cellulose surface

Optimasi pH dan Konsentrasi Elektrolit dalam Elektrokoagulasi Limbah Surfaktan

Surfactants are organic materials that act as active ingredients in detergents, soaps and shampoos which can reduce the surface tension of the water so that the particles attached to the materials being washed are released and float or dissolved in water thus polluting the environment. Therefor it is necessary to separate or change them into other harmless materials before being discharged into the environment. One of the methods used is electrocoagulation. The electrocoagulation method is an environmentally friendly method of treating liquid waste by combining the principles of coagulation, flotation and electrochemistry. In this study, the electrocoagulation method was carried out by varying pH and electrolyte concentrations in the simulated surfactant waste treatment. Surfactant levels were determined by spectrophotometer in methylene blue. The optimization of the method is done by determining the maximum absorption length, optimum pH, and the effect of adding electrolytes with different concentrations. The results showed that the maximum absorption at a wavelength of 659 nm. The electrocoagulation process runs optimally at pH 2 with the addition of 7mM Na2SO4 electrolyte resulting in a% removal of 65%

Model QSAR dari Turunan 3- tersubstitusi 4-Anilino Kumarin terhadap Aktivitas Anti-kanker Pankreas

Model Quantitative structure-activity relationship (QSAR) dari turunan 3-tersubstitusi 4-anilino kumarin terhadap aktivitasnya sebagai anti-kanker pankreas telah berhasil dibuat dan divalidasi.  Struktur molekul turunan 3-tersubstitusi 4-anilino kumarin dan aktivitas biologisnya yang digunakan disitasi dari penelitian yang telah dilakukan oleh Luo dkk. (Luo et al., 2017). Setiap molekul turunan 3-tersubstitusi 4-anilino kumarin yang digunakan dioptimasi menggunakan metode kalkulasi DFT/BPV86 6-31G. Model analisis QSAR dibentuk menggunakan metode Multi Linear Regression (MLR) dan model terbaik yang didapatkan adalah: Log IC50 = 4,02 + (-7,126 x qC7) + (-5,709 x qC8) + (6,845 x qC18), n = 18; r2train = 0.701; r2test = 0.849, Fkal/Ftab = 3,269; SEE = 0.230

Model QSAR dari Turunan 3- tersubstitusi 4-Anilino Kumarin terhadap Aktivitas Anti-kanker Pankreas

Model Quantitative structure-activity relationship (QSAR) dari turunan 3-tersubstitusi 4-anilino kumarin terhadap aktivitasnya sebagai anti-kanker pankreas telah berhasil dibuat dan divalidasi.  Struktur molekul turunan 3-tersubstitusi 4-anilino kumarin dan aktivitas biologisnya yang digunakan disitasi dari penelitian yang telah dilakukan oleh Luo dkk. (Luo et al., 2017). Setiap molekul turunan 3-tersubstitusi 4-anilino kumarin yang digunakan dioptimasi menggunakan metode kalkulasi DFT/BPV86 6-31G. Model analisis QSAR dibentuk menggunakan metode Multi Linear Regression (MLR) dan model terbaik yang didapatkan adalah: Log IC50 = 4,02 + (-7,126 x qC7) + (-5,709 x qC8) + (6,845 x qC18), n = 18; r2train = 0.701; r2test = 0.849, Fkal/Ftab = 3,269; SEE = 0.230

Isolasi dan Optimasi Transesterifikasi Minyak Biji Pepaya (Carica papaya) sebagai Sumber Energi Terbarukan

AbstrakLimbah biji pepaya Indonesia sebanyak 134.904,75 ton, mengandung minyak yang  berpotensi ditransesterifikasi menjadi metal serta berpotensi sebagai biodiesel. Penelitian ini bertujuan untuk menentukan: (1) kondisi optimum sintesis biodiesel dengan dua tahapan reaksi, (2) karakter metil ester sintetis melalui transesterifikasi, dan (3) komponen metil ester sintetis serta potensinya sebagai biodiesel. Tahapan penelitian eksperimental laboratoris ini, yaitu: (1) ekstraksi minyak biji  pepaya, (2) sintesis metil ester dari minyak biji pepaya, (3) karakterisasi metil ester sintetis dan uji potensi biodiesel meliputi penentuan densitas, viskositas, indeks bias, dan uji bilangan asam, dan (4) identifikasi komponen metil ester sintetis dengan GC-MS. Rendemen tertinggi metil ester sintetis diperoleh 75,82% b/b pada konsentrasi katalis KOH 1% b/b dengan karakteristik viskositas 4,76 cSt, massa jenis 0,85 g/mL, bilangan asam 0,70 mg KOH/g, dan indeks bias 1,44, maka metil ester sintetis telah memenuhi SNI 04-7182-2006 dan berpotensi sebagai biodiesel. Hasil uji GC-MS menunjukkan adanya metil palmitat 14,58%, metil oleat 78,87%, dan metil stearat 4,57%

Synthesis of biodiesel from waste cooking oil using heterogeneous catalyst of Na₂O/γ-Al₂O₃ assisted by ultrasonic wave

The synthesis of biodiesel via transesterification needs to be improved by the heterogeneous catalysts. So, the study aimed to determine the best conditions for the synthesis of biodiesel produced through a transesterification reaction using waste cooking oil with a Na2O/γ-Al2O3 catalyst assisted by ultrasonic wave. The steps were: catalyst preparation, oil preparation, esterification, trans-esterification reactions using methanol and various Na2O/γ-Al2O3 catalysts, and characterization. The results showed that the refined waste cooking oil using FTIR was known that there was still a carbonyl group indicating the presence of triglycerides. Free Fatty Acid content of waste cooking oil after esterification was 0.40%, so that the transesterification reaction could be carried out. The XRD results of the catalyst showed a conformity with the reference and it was determined by the Scherrer formula that the crystal size of the catalyst was 30.59 nm. The best condition for biodiesel synthesis was obtained at a catalyst ratio of 1:1 as much as concentration 3% w/w for 15 minutes of ultrasonication, 65 ℃, and molar ratio of methanol: oil (12:1), for the yield of 83.51%. After identification through GC-MS, it was known that the main components in the transesterified biodiesel from waste cooking oil were methyl elaidate (38.54%), methyl palmitate (30.90%) and methyl linoleate (16.61%)