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Yttrium aluminum garnet (YAG) is an important material which require high temperature of 1600°C in its solid-state reaction. To lower this temperature, mechanical activation process has applied to the system which make the crystal arrangement broken thus make it more reactive. This process results in homogeneous and fine particle distribution of Al2O3 and Y2O3 compared to manually mixed powders. Moreover, milling process also reduce the particle size of the Al2O3 and Y2O3 from 4694 nm and 349 nm down to 274 nm. This also lessen the crystallite size of Al2O3 and Y2O3 from 1010 and 164 Å to 310 and 50 Å respectively. Then, after calcination at 1100°C, the milled powders form YAG phase in the opposite of manually mixed powders which form YAM phase. YAG formed have nearly round shape with finer grain compared to manually mixed powders which still has large grain of Al2O3 and Y2O3. This formation temperature is much lower than the require conventional solid-state reaction.

This study investigated the relationship between gender, school type, school location, personality, and winning a medal among participants of the two largest student competitions in Indonesia, the National Science Competition (KSN) and the Entrepreneur-based Student National Competition (FIKSI), sponsored by the Indonesian Ministry of Education and Culture. Survey data were collected from 684 participants in KSN and 169 participants in FIKSI. The chi-square test and the logistic regression were employed using Jeffey’s Amazing Statistics Program (JASP) ver. 13. The results revealed a substantial relationship between gender, school location, school type, and personality on winning a medal in KSN, but none in FIKSI. Results also revealed that male participants and participants from Java and private schools were more likely to win medals in KSN than female participants and participants from outside Java and public schools. This study also found that neuroticism has a statistically significant relationship toward receiving a medal in KSN.

Acrylonitrile butadiene styrene (ABS) is one of the most common fused-filament feedstocks for 3D printing. The rapid growth of the 3D printing industry has resulted in huge demand for ABS filaments; however, it generates a large amount of waste. This study developed a novel method using waste ABS to fabricate electrospun nanofiber membranes (ENMs) for water filtration. Polyvinylpyrrolidone (PVP) was employed to modify the properties of waste ABS, and the effect of PVP addition in the range of 0-5 wt% was investigated. The results showed that adding PVP increased the viscosity and surface tension but decreased the conductivity of the precursor solution. After electrospinning, PVP could reduce the number of beads, increase the porosity and fiber diameter, and improve the wettability of the fabricated fibers. Moreover, the bilayer of ABS ENMs achieved a high flux value between 2951 and 48 041 L m

Electromagnetic waves show rapid development in electronics, telecommunications, and the military. One of the efforts to overcome the effects of electromagnetic interference is by developing microwave-absorbing materials. Barium hexaferrite is the best candidate for development as an absorber material. Microwave absorption in barium hexaferrite can be increased through Mg-Al doping and reducing the particle size. This study aimed to analyze sonication parameters to reduce the particle size by combining destruction methods using mechanical alloying followed by high-power ultrasonic irradiation. Barium hexaferrite was synthesized through mechanical alloying by mixing stoichiometric BaCO3, Fe2O3, Al2O3, and MgO (Sigma-Aldrich p.a 99%) (Mg-Al 0.4%wt). The samples continued the sintering process at 1200 °C for 2 h to grow crystal embryos. The optimal parameters for ultrasonic destruction were using a transducer:reactor diameter ratio of 1:10, a particle density of 5 g/250 mL, and adding a non-ionic surfactant of 0.01% at an amplitude of 55% and a sonication time of 8 h. These methods resulted in the saturation magnetization of 18.50 emu/g and a coercivity of 0.08 Tesla. The reduction in the particle size of BHF doped with Mg-Al was successfully up to 21 nm, resulting in a reflection loss of up to −40.8697 dB at 11.896 GHz (x-band, 8–12 GHz). The BHF nanoparticles doped with Mg-Al effectively absorbed up to 99.99% electromagnetic waves.

The effects of nanobubble on the growth environment, such as dissolved oxygen (DO) and total virus-bacteria, and growth performance, such as growth, feed conversion ratio (FCR), survival rate (SR), total harvest, and productivity, were investigated in Penaeus vannamei shrimp ponds. The present study was carried out in 50 m2 indoor raceway ponds for 81 days with stocking density being set to 680 shrimp m−3 in two types of treatment: nanobubble and diffuser aerator. A paddlewheel was used to distribute the oxygen saturation levels throughout the ponds. The presence of nanoparticles was detected using a dynamic light scattering method and was reported to be 82.38 nm in size and −26 mV for zeta potential value. DO was significantly higher under nanobubble treatment. Total virus-bacteria and FCR decreased, whereas SR, growth (weight and length), total harvest, and productivity increased with increasing DO. The SR was reported to reach 95%. The average weight and length of P. vannamei were 15.1 ± 1.8 g and 13.1 ± 1.1 cm, respectively. The total harvest and productivity have doubled to 436 kg and 8.7 kg/m3. The results revealed that nanobubble has managed to maintain DO at the optimal range and affected the shrimp growth significantly (P

ZnO thin films are deposited on glass substrate using sol–gel spin coating methods with various annealing temperatures. The structural, morphological, and optical properties are studied by XRD, FE-SEM, UV–Vis, and photoluminescence spectrophotometer. The photocatalytic activity was assessed by examining the decomposition of Rhodamine-B (Rh-B) dye under UV illumination. The result shows that the ZnO films have a hexagonal wurtzite structure with highly preferred c-axis orientation. The (101) crystallographic plane appears at higher annealing temperatures. The transmittance of ZnO films is more than 80%, with a slight red shift in absorption and decrease in the optical band gaps as the annealing temperature increases to some extent. The photoluminescence spectra of the ZnO films at room temperature demonstrated the ultra-violet (UV) emission with a peak emission at 410 nm (3.03 eV). According to the photocatalytic activity examination, the presence of (101) plane in the c-axis oriented ZnO films enhances the photocatalytic performance by a factor of 5. The result revealed that ZnO films with multi-orientation structure possess better photocatalytic performance than that of the single-orientation ones. In particular, the photocatalytic performance is highly contributed by the polar crystal plane and slightly improved by the crystallinity and surface morphology.

Based on the X-Ray Fluorescence test it was identified that the calcium content in green mussel shells was very high with concentration about 93.83%. The calcium is the main constituent of hydroxyapatite besides phosphorus, so the purpose of this study is to identify a very good potential for synthesized hydroxyapatite from green mussel shells, which is considered the waste of shells that cause environmental pollution. Hydroxyapatite synthesized from green mussels using precipitation method, calcium from green was reacted with phosphate obtained from phosphoric acid. The Fourier transform infrared spectrum show that the functional group in powder is a functional group of hydroxyapatites. The FTIR chart of shellfish hydroxyapatite soaked in acetone and after the precipitation process is heated again to 900°C is the most similar graph to the FTIR commercial HA graph. The results of the X-Ray Diffraction test also prove that the clam shell with this treatment has a diffraction pattern resembling standard hydroxyapatite.

Screw Compressor is one type of air compressor in the main utility at the DSLNG LNG Plant. This Screw Compressor is used as instrument water (clean, oil-free, and dry air) produced by the Air Compressor Package (Tag No. 065-C-1001 A / B / C), which is dried by the Air Dryer Package (065-V-1001A / B) until it reaches a dew point of -40 degrees Celsius before being accommodated in the Instrument Air Receiver (065-D-1002). Water instruments are needed to operate instrumentation equipment such as actuated valves, control valves, and others.This research was conducted to analyze the failure of rotary screw compressors and their modifications. The failure occurred in the lube oil (lubricating oil), which was contaminated by water from the surrounding wet air. This failure analysis is done with a fishbone diagram and plans to overcome the problem by modifying the breather system. Analysis of this failure by looking for the water content into the lubricating oil. Know the results of the analysis of the increase in the vibration value of the bearing screw elements and check the effect of corrosion in the lubrication system using a borescope. In addition, taking corrective action (repair) so that there are no recurring problems by making modifications to the Breather System on the gear casing

The bioactive functions of oligosaccharides from human milk have been reported by many studies. Many of oligosaccharides isolated from colostrum and/or milk of dairy animals have been reported to have similar chemical structures with those in human colostrum and/or milk. It has been proved by several studies that the oligosaccharides with similar chemical structure shared common bioactivities. Among domesticated dairy animals, bovine/cattle, caprine/goat, and ovine/sheep are the most commonly used species to isolate oligosaccharides from their colostrum and/or milk. Several studies on the oligosaccharides from goat colostrum and milk have revealed similar properties to that of human milk and possess the highest content of sialyl oligosaccharides (SOS) as compared to other ruminants. Indonesia ranks first in Association of Southeast Asian Nations (ASEAN) for goat milk production. Therefore, goat milk is the second most consumed milk in the country. The most reared dairy goat breed in Indonesia is Etawah Grade. However, oligosaccharides from Indonesia dairy animals including goat, have not been characterized. This is the first study to characterize oligosaccharides from Indonesia dairy animals. The present study was aimed to isolate and characterize oligosaccharides, specifically SOS from the colostrum of Etawah Grade goats by using proton/

Aluminum alloy 5052 (Al 5052) is one of the metals used as a bipolar plate in a Proton Exchange Membrane Fuel Cell (PEMFC) due to has its light mass and being easy to form, and, has high conductivity and resistivity properties. This material is prone to corrosion and current knowledge to protect its surface is currently lacking. The product of PEMFC produces electrical energy, hot steam (313 – 353 K), and water. These conditions have an impact on the degraded bipolar plate caused by the acidic nafion membrane. This increases the risk of corrosion on the cathode side of the bipolar plate. Coating with a green inhibitor using the electrophoretic deposition technique (EPD) is one way to deal with the corrosion that occurs. The analysis method used electrochemical with potentiodynamic polarization techniques, electrochemistry impedance spectroscopy (EIS), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). In this study, green inhibitor D-galactose was used with a concentration of 0.5 – 1.5 g and an, EPD time of 15 – 45 minutes in 0.5 M sulfuric acid (H2SO4) media pH 1-4. Potentiodynamic polarization analysis at the lowest corrosion current value (Icorr) at demonstrates (the inhibitor concentration of 1.5 g with an and EPD time of 45 minutes) resulted corrosion rate of Al5052 before EPD was 0.0075 mmPY while the corrosion rate of Al5052 after EPD was 0.0041 mmPY with (inhibitors efficiency 45.2%). The FTIR spectrum, broad peak appeared in the range of 3000-3600 cm-1, which refers to the formation of hydrogen bonding of hydroxyl group. Methyl group of D-galactose also appear on 2918 cm-1 and 2850 cm-1 which attributed to =CH2 asymmetric stretch and −CH3 symmetric stretch, respectively. Carbonyl group on 1500 – 1700 cm-1 represent C=O bond of amide, and aldehyde. Peak 1097 – 1035 cm-1 which attributed to C-O were connected to the secondary and primary alcohols. The resistance value for Al5052 before and after EPD are 1.2 kΩ/cm2 after and 2.2 kΩ/cm2, respectively. Here we find that the resistance increases with the increasing concentration and time of EPD. The results cross section Al5052 within average 29.8 μm, and morphology with SEM Al5052 before EPD showed pitting corrosion. On the other hand, the image of Al5052 inhibitor coating 1.5 gr with EPD of 45 minutes shows a smooth surface and visible black lumps, suggesting Al5052 is successfully reduced a corrosion rate by the D-galactose. Our simple and robust method inferred a protection route towards a viable and physically stable green inhibitors.

We investigated the multiscale characters of the crystal structure of the oxynitride perovskite LaTiO2N. While X-ray diffraction results identified the average structure as being centrosymmetric, we detected a signature of unknown structural deformation. By viewing the local structure, we unveiled the formation of a polar structure at the nanoscale.

Nanogold merupakan nanopartikel metal inorganik (5-400 nm) dan memilki sifat fisikokimia yang unik serta lebih unggul dibandingkan dengan bulk-nya. Nanogold dapat diperoleh dengan berbagai macam metode sintesis. Proses reduksi prekursor emas oleh agen pereduksi merupakan tahapan yang penting dalam proses sintesis nanogold yang dapat menghasilkan nanogold dengan karakteristik yang termodifikasi sehingga berpengaruh kepada pengaplikasian dan toksisitasnya. Penelitian ini bertujuan untuk mengkaji artikel-artikel terkait nanogold yang meliputi perkembangan metode sintesis, karakteristik, sumber bahan yang dapat digunakan sebagai agen pereduksi, penetrasi kulit nanogold, dan toksisitasnya melalui metode yang terstruktur dan sistematis yaitu Systematic Literature Review (SLR). Pencaharian artikel melalui situs PubMed dengan periode terbitan lima tahun terakhir dan menggunakan kombinasi kata kunci, yakni “gold nanoparticles”, “synthesis”, “characteristic”, “skin penetration”, “toxicity”, dan “applications”. Diperoleh 31 artikel dari 809 artikel yang memenuhi tahap kriteria inklusi dan eksklusi serta Quality Assessment (QA). Hasilnya memperlihatkan bahwa 27 artikel diantaranya yang mencantumkan metode sintesis nanogold didominasi oleh penggunaan metode dengan pendekatan “green synthesis” terutama secara biologi dengan memanfaatkan kandungan biokimia dari sumber alam sebagai agen pereduksi. Penggunaan agen pereduksi secara tidak langsung mempengaruhi karakterisitik nanogold. Instrumen FTIR (Forier-Transform Infrared Spectroscopy) mengkonfirmasi adanya gugus fungsi atau biokomponen utama dari sumber bahan alam sebagai agen pereduksi. Selanjutnya, nanogold akan dikarakterisasi dengan spektrofotometri absorbansi UV-Vis, analisis TEM (Transmission Electron Microscopy), SEM (Scanning Electron Microscopy), XRD (X-Ray Diffraction), dan (Dynamic Light Scattering). Kemampuan nanogold berpenetrasi ke dalam kulit dengan mudah, cepat, dan hanya mengakibatkan kerusakan secara lokal membuat nanogold banyak digunakan sebagai obat atau agen pembawa obat. Melalui uji perubahan warna MTT (Microtetrazolium (3-(4,5-Dimetil-2-Tiazolil)-2,5-difenil-tetrazolium Bromida) dan dilihat dari nilai IC50 dan persentase viabilitas sel, nanogold menunjukkan efek toksik terhadap sel kanker dan aman untuk sel normal dalam tubuh.

We investigated the multiscale characters of the crystal structure of the oxynitride perovskite LaTiO2N. While X-ray diffraction results identified the average structure as being centrosymmetric, we detected a signature of unknown structural deformation. By viewing the local structure, we unveiled the formation of a polar structure at the nanoscale.

In the present study, an Al–Ni–Cr–Cu–MoO3–SiO2 composite coating with varying elemental compositions was deposited using the mechanical alloying technique. The composite coating structure before and after an oxidation test was studied using X-ray diffraction (XRD), three-dimensional optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). A cyclic oxidation test was conducted in an 800 °C air atmosphere for 10 cycles (200 h). Based on the XRD, SEM, and EDX analyses, the coating comprised composite-refined Al, Ni, Cr, and Cu particles as well as coarse SiO2 particles. The composite coating had a thickness in the range of 36–59 μm, with good and continuous adherence to the substrate. The cyclic oxidation curve of the composite coating followed a parabolic rate law. The sample that contained 5.3 wt% MoO3 showed the best oxidation resistance after 10 oxidation cycles at 800 °C. This sample had a lower mass gain than the other samples. Moreover, this sample had a Kp of 1.2 × 10−3 mg2/cm2·s. Protective Al2O3 oxides formed on the composite coating surface with a thickness of 0.75–1.89 μm. This oxide scale was dense and fully adhered to the coating, thereby improving oxidation resistance.

A new pulverization process utilizing thermal treatment in controlled atmosphere was developed. The samples, including SrTiO3 single crystals, TiO2 single crystals and BaTiO3 ceramic, were pulverized into nano-sized powder by heating in gas stream containing air and ammonia (NH3) at high temperature. Although the detailed mechanism for this pulverization process is still unclear but it is evident that thermal treatment in NH3 based atmosphere containing small fraction of air (5–10%) causes not sintering but pulverization. Efficient synthesis of an oxynitride compound, LaTiO2N, was demonstrated by using nano-sized La2Ti2O7 precursor prepared by utilizing this new powder preparation process.

Nano-sized manganese oxide was synthesized by the solvothermal method. Manganese sulfate was used as a precursor, which is obtained from the Sumbawa manganese ore. Two kinds of the precipitating agent, ammonium persulfate and sodium hydroxide, were used in this study and the effect on the solvothermal product were examined thoroughly. The solvothermal temperature and time were 120°C for 18 hours, respectively, for both precipitating agents. The results showed that the phase of manganese oxide was influenced by the precipitating agent, as indicated by X-ray diffraction analysis. Phase 2 was obtained from the reaction between MnSO4 and ammonium persulfate, while Mn3O4 for the sodium hydroxide. The formation of a-MnO2 was influenced by the excess of NH4 + which came from the manganese ore leaching into MnSO4. One notable finding in this study is that the morphology of manganese oxide was also affected by the precipitating agent. For instance, the shape of MnO2 and Mn3O4 was needle and sphere, respectively. Moreover, the strict long thinner needle of 2 was formed and the aspect ratio increased at a higher temperature. While the particle size of Mn3O4 decreased with the increased temperature. These results imply that variation of a precipitating agent is imperative to obtain the specific manganese oxide product, including the shape.

The spent bleaching earth from the palm oil refining industries contains various contaminants, including free fatty acids and hazardous material. The conventional procedure is harmful to the environment. In this study, spent bleaching earth (SBE) was successfully regenerated by calcination and acid-activation process. The calcination process was performed at 500, 600 and 700°C for 2, 3 and 4 h. All samples were then mixed with CaCO3 and lastly activated with aqueous acid. The results showed the SBE color restored at calcination temperature higher than 500°C, even though the decomposition of the volatile compound was removed at 680°C according to thermal gravimetric analysis. Treatment affected the clay structure and mostly removed the impregnated organic matter. The primary phase of regenerated SBE is similar to virgin bleaching earth (VBE), implying the calcination and acid-activation is not alter the phase. Moreover, the adsorbent capacity of regenerated SBE was comparable with VBE, showing the regenerated SBE has promising potential for many applications, in particular for the palm oil refining industry. Regenerated SBE gave significantly larger specific surface area, microporous surface area and total pore volume with smaller the average pore diameter.

Dense silicon carbide (SiC) was successfully sintered from amorphous polysilazane (PSZ) using hot pressing at 1750oC for 1 hour under an applied pressure of 20 MPa in Ar atmosphere. The effect of β-SiC powder as a filler on the density, phase, micro structure and hardness were examined. Al2O3 and Y2O3 were used as sintering additives through the liquid phase sintering mechanism. The phase analysis showed the formation of SiC after sintering of amorphous PSZ. However, α-SiC was a dominant phase and the amount of α-SiC decreased with the addition of β-SiC powder. The relative density of sintered SiC was obtained in range 99.6 -99.7% regardless of the addition of β-SiC powder. Sintered SiC from amorphous PSZ revealed significant shrinkage compared to sintered SiC from β-SiC powder, while the minimum shrinkage was achieved by the addition of 70% β-SiC into amorphous PSZ. However, the hardness of sintered SiC did not correlate with the addition of β-SiC powder, with highest hardness of 26.4 GPa, which is SiC from solely β-SiC powder. This result indicates that amorphous PSZ is an alternative precursor to fabricate dense SiC.

In this study, we investigated the ability of polysilazane as starting materials to fabricate SiCf/SiC composite prepared by slurry infiltration method, i.e., vacuum infiltration (VI) and electrophoretic infiltration (EPI). After infiltration, sintering was performed using hot pressing vacuum furnace at 1750 °C for 1 h in Ar atmosphere and applied pressure of 20 MPa. Phase analysis revealed the formation of a-SiC for EPI, while a-SiC and p-SiC were detected for VI. It seems the transformation of (3- to a-SiC enhances significantly in the EPI, resulting in single-phase a-SiC. Moreover, the presence of excess carbon after sintering indicated that the amount of Si and C was not stoichiometry. The density of SiCf/SiC composite infiltrated by VI and EPI was 2.68 and 2.92 g/cm3, respectively, corresponding to 81.6 and 90.9% of theoretical density. Although the density is quite different, the average flexural strength for VI and EPI was 174 ± 5 and 200 ± 7 MPa, respectively, which does not differ significantly. However, the tail extension was observed for both samples, indicates the toughness increase compared to monolithic ceramic. This study indicates that polysilazane can be used as an alternative precursor for the fabrication of SiCf/SiC composites using a slurry infiltration method.

The aim of this study is to examine the effect of nano hydroxyapatite in the toothpaste and its effect on the pH and microbial activity. Nano-hydroxyapatite (nHAp) is considered one of the materials that have high biocompatibility for biomimetic material due to its chemical and morphological similarity with dental apatite. Additionally, it has been documented to possess antibacterial potentials. The present study was conducted to identify the relationship between oral microenvironment pH change and its role in the Streptococcus mutans viability, a common pathogen in the oral cavity. Change in pH is closely related to number of Streptococcus mutans as the main cariogenic organism and acid-producing bacteria. The study was carried out using 0.25%, 0.7%, and 1.5% concentration of HAp in toothpaste formulation and commercial toothpaste as control. Our studies showed that the most significant pH fall was observed in 1.5% and 0.7% nHAp. However, in 60 minutes, all nHAp groups were able to restore pH into neutral, especially in the 0.7% nHAp, which reached a pH of 7. As a comparison, the commercial toothpaste only returned to 6 within 1 hour. Experimental method of this study is In vitro oral microenvironment pH and microbiological analysis on teeth fragment. The detailed data about microstructure and antibacterial activity will be presented.

Kalsium Pirofospat adalah biomaterial yang sangat baik untuk digunakan sebagai pengganti tulang atau gigi yang rusak ataupun retak. Kalsium Pirofospat bersifat biokompatibel, bioaktif dan memiliki komposisi kimia yang mendekati komposisi pada tulang dan gigi manusia. Namun biomaterial ini memiliki kekurangan yaitu sifat mekanisnya yang rendah apabila digunakan untuk menerima beban yang berat. Peningkatan sifat mekanik kalsium pirofospat dapat dilakukan dengan menambahkan material zirkon. Oleh karena itu, pada penelitian ini dilakukan kajian perubahan fasa kalsium pirofospat dengan penambahan zirkon pada temperatur tinggi. Komposisi zirkonia yang ditambahkan sebesar 5% dan 10% (w/w). Pencampuran kalsium pirofosfat dilakukan menggunakan High Energy Milling (HEM) dengan Ball Powder Ratio (BPR) sebesar 5:1 selama 30 menit. Campuran selanjutnya dipanaskan pada temperatur 1000 selama 60 menit. Hasil karakterisasi menggunakan XRD menunjukan bahwa perlakuan pemanasan dapat mendekomposisi kalsium pirofosfat dan terbentuknya CaZrO3. Pemanasan juga menyebabkan ukuran partikel semakin besar. Hasil SEM menunjukkan ukuran mikrostruktur CPP TA yang semula 590±43nm menjadi CPP TAZ5 1,212±268µm dan CPP TAZ10 1,324±384µm. Sedangkan untuk CPP TB yang semula 455±32nm menjadi CPP TBZ5 1,112±546µm dan CPP TBZ10 1,123±392µm. Kata kunci: Kalsium Pirofospat, Zirkonia, High Energy Milling

The objectives of this study were to evaluate the effect of nitrogen nanobubble for storing fresh yellowfin tuna (Thunnus albacares). Yellowfin tuna were stored for 10 days in two types of treatment: nitrogen nanobubble (NNB) and conventional packaging process (CPC). Two methods including qualitative (organoleptic) and quantitative (histamine and mercury content, and total plate count of bacteria) were analyzed to determine the treatments effect on post-harvest quality, microbial population, and shelf-life of the fish. Results show that nitrogen nanobubble is proven to maintain dissolved oxygen levels remain in low conditions ( < 1 mg/L) during treatment. Although the organoleptic properties for both treatments do not show any significant differences, the lowest histamine and mercury contents are found in treatment NNB at 11.8 mg/kg and 0.14 mg/kg, respectively. The microbes in treatment NNB is achieved levels deemed safe (based on national standards) at 1.8 × 104 colonies/g, E. coli content Salmonella sp. are not detected. Our results suggest that treatment NNB is preferable for preservation process of fresh yellowfin tuna and might improve to extend the shelf-life.