SILIKA BEBAS NATRIUM DARI LIMBAH SEKAM PADI SEBAGAI BAHAN DASAR PEMBUATAN MINERAL TRIOXIDE AGGREGATE

One of the basic ingredients of making White Mineral Trioxide Aggregate (MTA) was silica. The sources of silica was from white rice husk ash (RHA) and silica extracted from RHA. Silica could be extracted from natural ingredients in the form of rice husk ash. The purpose of this study were to extract silica from rice husk ash and purify the silica extracted by washing using distilled water to free sodium, so that it could be used as the basic ingredient in making MTA. Sodium was a hygroscopic metal that could cause the presence of pores in MTA material if applied to the teeth. The amount of washing volume varies to a certain volume which indicates that silica was free Na. Based on the results of the experiment it could be concluded that the washing of silica by stirring with distilled water would produce free Na silica by washing 450 mL. This wasnot proven at peak 2θ (30⁰), as well as proof of the presence of silanol and siloxane groups before and after washing with FTIR spectroscopy. In addition, the washing volume also affects the intensity of the –OH peak in wave numbers 1635,64 cm-1  the more volume used, the intensity of the –OH group increases, so that the water hydrated in silica also increases. Silica free Na would be used as the starting material for making MTA which was applied to teeth medicament or root canal treatmen

Struktur dan Kelimpahan Populasi Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) di Pasaman Barat, dan Pengendalianya Menggunakan Seks Feromon

Spodoftera frugiperda merupakan salah satu hama pada tanaman jagung, Serangan S. frugiperda sudah banyak dilaporkan diantaranya oleh Trisyono et al. (2019) di Lampung dengan intensitas serangan 100 %. Serangan S. frugiperda pertamakali dilaporkan di Pasaman Barat tahun 2019 (Nonci et al., 2019). Namun data yang ditampilkan belum mencakup seluruh wilayah di Pasaman Barat. Tujuan penelitian ini untuk mengetahui struktur, kelimpahan populasi, sebaran di Pasaman Barat, dan keefektifan feromon dalam mengendalikan S. frugiperda. Penelitian dilaksanakan di Pasaman Barat, bulan Februari - April 2022, dengan metoda survey, purposive sampling, ditentukan satu lahan tanaman jagung fase vegetatif. Disetiap lahan ditetapkan lima petak sampel yang terdiri dari 20 rumpun tanaman per petak sampel, kemudian dilakukan pengamatan pada setiap tanaman pada petak sampel. Perangkap seks feromon di pasang sebanyak lima unit pada setiap lahan, kemudian dilakukan pengamatan setiap satu minggu sekali sebanyak lima kali pengamatan. Hasil penelitian menunjukan struktur populasi yang di temukan di Pasaman Barat yaitu, kelompok telur, larva dan imago, dengan kelimpahan populasi tidak terlalu tinggi hanya 32 ekor larva per dua puluh rumpun tanaman, dan pola sebaran merata. Hasil pengujian pengendalian S. frugiperda menggunakan seks feromon sangat rendah dengan jumlah imago terperangkap paling banyak hanya 8 ekor selama lima minggu pengamatan. Kesimpulan; struktur S. frugiperda yang ditemukan dilapangan berupa kelompok telur, larva dan imago, dengan kelimpahan populasi S.frugiperda yang tidak terlalu tinggi dan pola sebarannya merata. Sedangakan penggunaan seks feromon untuk pengendalian S. frugiperda masih belum efektif

EFFECT OF ACID CONCENTRATION ON CHARACTERS OF SILICA GEL SYNTHESIZED FROM SODIUM SILICATE

In this research, synthesis and characterization of silica gel from sodium silicate through sol-gel process using H2SO4, HCl, and citric acid have been investigated. Synthesis was carried out by mixing and stirring  20 mL of H2SO4, HCl or citric acid  at certain concentration with 50 mL of sodium silicate solution (Na2O 0.17 M and SiO2 0.61 M) for one hour and let to form gel.  The gel was washed with distillated water, and dried in an oven at 100 oC. Characterization of silica gel was carried out by determination of acidity, water adsorption capacity, and water content. Identification of functional group and structure were identified using x-ray diffractometer (XRD) and infrared (IR) spectrophotometer, respectively.  Results showed that at a range of investigated concentration (0.6 - 3.0 M) the increase of concentration, formation of gel with H2SO4 tended to be faster, but with HCl and citric acid to be slower. The increase of acid concentration caused water content, water adsorption capacity, and acidity of the silica gel resulted with HCl and citric acid tended to be increased, increased, and increased, but with H2SO4 to be decreased, increased, and decreased, respectively. Based on the IR spectra and XRD data, it could concluded that the synthetic silica gels contained silanol (Si-OH) and siloxane (Si-O-Si) and were amorphous, showing similar pattern to kieselgel G 60 produced by Merck.   Keywords: silica gel, adsorption capacity, sodium silicate, acidit

Pengaruh Gear Ratio Transmisi dan Grade Jalan Terhadap Fuel Consumption Truck Batubara dengan Pendekatan Regresi Linier Berganda

Transmission Gear Ratio usually affects torque and speed. The effect on fuel consumption for coal trucks with a capacity of 20 tons needs technical analysis and experiment to obtain actual data. In the experiment process using a standard transmission issued by the factory that is with 8 forward speed and 1 reverse speed. Experiment is done by comparing the calculation of fuel consumption with the use of transmission. Tests carried out using 2 dump trucks, 6 times sampling, 8-Speed, 30 km distance, with variations in the grade 8 segments and loads. From the results of testing and calculation of fuel consumption with parameter 8 variations in road grade and loaded, different fuel usage is obtained for each road segment and in load or empty conditions. When high grade fuel consumption also increases, when loaded conditions fuel consumption increases. Road grade and loaded conditions affect the use of fuel consumption. The use of transmission speed or gear ratio also affects fuel consumption

Synthesis and Characterization of Biphasic Calcium Phosphate Substituted Cerium as a Potential Osteoporotic Bone Filler

Biphasic calcium phosphate substituted cerium (BCP/Ce) is a potential material for osteoporotic bone filler. Synthesis of BCP/Ce was conducted by the sol-gel method. This work aimed to study the influence of cerium as a precursor on the crystal structures, surface properties, and agglomeration of BCP/Ce. A series of samples were prepared by various Ce percentages (0.5–16%) and a constant molar ratio of (Ca + Ce)/P = 1.2. A structural study by Rietveld refinement calculation confirmed that synthesis without Ce produced BCP that contained hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) at a ratio of 93:7. The presence of Ce increased β-TCP content to 73% for the use of Ce 8%. None of Ca in the HA structure was replaced by Ce. Otherwise, Ce replaced Ca in β-TCP structure by isomorphic substitution at the Wyckoff site of 6a (0,0,-0.085) or Ca (4) position. As the maximum occupancy of Ca (4) = 43%, about 17% of that was substituted by Ce for the use of 14% Ce. Ce was found in two states as Ce3+ and Ce4+ ions with Ce3+/Ce4+ ratio > 1. The presence of Ce on the particle surface caused a change in the particle shape, from plate-like to spherical. The particle size decreased to <100 nm with the increase of Ce content. The rise of Ce content in BCP decreased the luminescent property due to the increase of oxygen vacancies. The negative value of Zeta potential confirms that BCP/Ce surface can accommodate bone cell proliferation

EFFECT OF DIATOMEAOUS EARTH TREATMENT USING HYDROGEN CHLORIDE AND SULFURIC ACID ON KINETICS OF CADMIUM(II) ADSORPTION

In this research, treatment of diatomaceous earth, Sangiran, Central Java using hydrogen chloride (HCl) and sulfuric acid (H2SO4) on kinetics of Cd(II) adsorption in aqueous solution has been carried out. The work was conducted by mixing an amount of grounded diatomaceous earth (200 mesh in size) with HCl or H2SO4 solution in various concentrations for two hours at temperature range of 100 - 150oC. The mixture was then filtered and washed with water until the filtrate pH is approximately 7 and then the residue was dried for four hours at a temperature of 70oC. The product was used as an adsorbent to adsorb Cd(II) in aqueous solution with various concentrations. The Cd(II) adsorbed was determined by analyzing the rest of Cd(II) in the solution using atomic absorption spectrophotometry. The effect of treatment was evaluated from kinetic parameter of adsorption rate constant calculated based on the simple kinetic model. Results showed  that before equilibrium condition reached, adsorpstion of Cd(II) occurred through two steps, i.e. a step tends to follow a reaction of irreversible first order  (step I) followed by reaction of reversible first order (step II). Treatment with acids, either hydrogen chloride or sulfuric acid, decreased adsorption rate constant for the step I from 15.2/min to a range of 6.4 - 9.4/min.  However, increasing concentration of acid (in a range of concentration investigated) did not give significant and constant change of adsorption rate constant. For step II process,  adsorption involved physical interaction with the sufficient low adsorption energy (in a range of 311.3 - 1001 J/mol).     Keywords: adsorption, cdmium, diatomaceous earth, kinetics

Effect of 35% sodium ascorbate on calcium and phosphorus loss in dentin bleached by 35% hydrogen peroxide

Post bleaching procedures often have free radicals trapped in dentin tubule and interprismatic enamel, leading to demineralization and denaturation. Sodium ascorbate is an antioxidant substance known to bind residual free radicals to stop demineralization and denaturation. The purpose of the study was to assess the calcium and phosphorus loss from the dentin surface following bleaching by 35% hydrogen peroxide and reversal by 35% sodium ascorbate andthe surface structure of the dentin. Six sound premolars were divided into their crown and root sections, with the crown subsequently being cut into four equal parts to obtain 24 samples. The calcium and phosphorus contents as well as the surface structure of the dentin were assessed using SEM-EDX. These were then divided into four groups, each containing six samples. Group A (control): the samples were bleached by 35% hydrogen peroxide, immersed in an artificial saliva, stored in an incubator at 37 °C for seven days. Group B: the samples were bleached by 35% hydrogen peroxide followed by the application of 35% sodium ascorbate for 5 minutes (once). Group C: the samples were bleached by 35% hydrogen peroxide followed by the applications of 35% sodium ascorbate (twice). Group D: the samples were bleached by 35% hydrogen peroxide followed by the applications of 35% sodium ascorbate (threetimes). The calcium and phosphorus contents as well as the surface structure of the dentin were re-assessed using SEM-EDX at the same locations. The results of one-way ANOVA indicated a difference in the calcium loss in the four treatment groups (p<0.05), but there was no difference in the phosphorus loss. An LSD test showed that there was a difference in the calcium loss between group A and groups C and D or between group B and groups C and D. The dentin tubules in group A were larger than group B, C and D. The frequency of 35% sodium ascorbate application had an effect on the calcium loss and the surface structure in the dentin bleached by 35% hydrogen peroxide

Preparation and Characterization of White Mineral Trioxide Aggregate (WMTA) using Silica from Rice Husk Ash

The preparation of white mineral trioxide aggregate (WMTA) was carried out using a solid technique using silica (SiO2) from rice husk ash (RHA). The process included extraction of SiO2 from RHA, the effect of SiO2 composition on material characterization and material compressive strength. Silica was extracted from RHA using NaOH and washed with distilled water until it was sodium-free. WMTA was prepared by mixing extracted SiO2, Bi2O3 commercial (18.0%), CaO commercial and Al2O3 commercial (2.0%), and the mixture was heated at various temperatures (900, 1000, 1100 oC). MTA was made from two variation silica sources: RHA and extracted silica, and each source varied at 15, 20, and 25% by weight, while the CaO content was adjusted. Characterization was carried out by FT-IR spectrophotometry, XRD and UTM for compressive strength measurement conducted after cementation for a day. The RHA extraction results were obtained from sodium-free SiO2. The peak showed the success of WMTA preparation at wave number 910 cm-1 in FTIR spectra, indicating the presence of C-S-H and C3S, C2S, and C3A bonds both before and after thermal treatment in XRD data. The highest compressive strength test after cementation for one day (3.21±0.13MPa) was given by WMTA using RHA, heating at 900 oC, and the percentage of CaO and SiO2 were 60% and 20%, respectively

A STUDY ON INTERACTION OF Cd(II) AND DIATOMACEOUS EARTH IN ADSORPTION PROCESS

In this research, interaction occurring in adsorption process between Cd(II) and active site of diatomaceous earth has been studied. The study was carried out by evaluating Cd(II) adsorption on diatomaceous earth at various pHs, either for the earths without treatment, those after being heated or those treated with sulfuric acid and hydrogen chloride. Adsorption was performed by mixing diatomaceous earth, without and with treatments, and Cd(II) solution for one hour at various pHs (2 - 7), and un-adsorbed metallic ion was analyzed by atomic absorption spectroscopy (AAS). The treatments of diatomaceous earth included heating at temperatures of 300, 500, and 900oC for four hours, treatments with acids (3, 8, and 12 M of H2SO4, and 3, 15, and 18 M of HCl solutions for two hours at 150-200oC). Results showed that the increasing of pH from 2.0 to 3.0 and from 6.0 to 7.0 inclined adsorption of Cd(II) from 13.2 to 23.3 mg/g and from 24.0 to 26.4 mg/g, respectively. At a pH range of 3.0 - 6.0 the adsorption slightly increase from 23.3 to 24.0 mg/g. Heating of diatomaceous earth higher than 500oC caused the adsorption capability to be independence of the pH of solution. On the other hand, treatments with acids (H2SO4 and HCl) caused adsorption capability increased significantly with the increase in pH from 3.0 to 6.0. Adsorption evaluation at the pH range investigated showed that adsorption of Cd(II) on diatomaceous earth may be through interaction between Cd2+ and functional groups of T-OH (T = Si/Al).   Keywords: adsorption, adsorbent, cadmium, diatomaceous eart

A Study on Interaction of Cd(II) and Diatomaceous Earth in Adsorption Process = Kajian Interaksi Cd(II) dengan Adsorben Tanah Diatomit Pada Proses Adsorpsi.

In this research, interaction occurring in adsorption process between Cd(II) and active site of diatomaceous earth has been studied. The study was carried out by evaluating Cd(II) adsorption on diatomaceous earth at various pHs, either for the earths without treatment, those after being heated or those treated with sulfuric acid and hydrogen chloride. Adsorption was performed by mixing diatomaceous earth, without and with treatments, and Cd(II) solution for one hour at various pHs (2 â 7), and un-adsorbed metallic ion was analyzed by atomic absorption spectroscopy (AAS). The treatments of diatomaceous earth included heating at temperatures of 300, 500, and 900°C for four hours, treatments with acids (3, 8, and 12 M of H2SO4, and 3, 15, and 18 M of HCI solutions for two hours at 150-200°C). Results showed that the increasing of pH from 2.0 to 3.0 and from 6.0 to 7.0 inclined adsorption of Cd(II) from 13.2 to 23.3 mg/g and from 24.0 to 26.4 mg/g, respectively. At a pH range of 3.0 â 6.0 the adsorption slightly increase from 23.3 to 24.0 mg/g. Heating of diatomaceous earth higher than 500°C caused the adsorption capability to be independence of the pH of solution. On the other hand, treatments with acids (H2SO4 and HCI) caused adsorption capability increased significantly with the increase in pH from 3.0 to 6.0. Adsorption evaluation at the pH range investigated showed that adsorption of Cd(II) on diatomaceous earth may be through interaction between Cd2+ and functional groups of T-OH (T = Si/A1). Keywords: adsorption, adsorbent, cadmium, diatomaceous earth