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Abstrak :
Nanostructured zincoxide (ZnO) was synthesized via a sonochemical method. The effect of the duration of ultrasonic irradiation in a continuous mode on the generated particles was investigated. Additionally, the effect of flowing either air or nitrogen during the sonication process was investigated. Zinc nitrate and ammonia water-based solutions were selected as chemicals without the addition of other surfactants. The generated particles indicated that a wurtzite structure of ZnO in a hexagonal phase was formed with a crystalline size that increased as the ultrasound irradiation time increased. The morphology of the generated ZnO particles could be changed from flowerlike to needlelike structures via continuous ultrasound irradiation over one to two hours, resulting in increases in the particle lengths and decreases in the particle diameters from 200 to 80 nm. Photoluminescence intensity was also increased with increases in the ultrasonic irradiation times. Photoluminescence spectra were also influenced by the atmospheric environment. Two bands centered at 390 and 500 nm were generated under a nitrogen environment. On the other hand, a single wide band with a peak at around 430 nm was found for particles generated under an air environment. It can be applied for light emitting diodes (LED) or laser fabrication with a controlled emitting band.

Abstrak :
Nanostructured zinc oxide (ZnO) was synthesized via a sonochemical method. The effect of the duration of ultrasonic irradiation in a continuous mode on the generated particles was investigated. Additionally, the effect of flowing either air or nitrogen during the sonication process was investigated. Zinc nitrate and ammonia water-based solutions were selected as chemicals without the addition of other surfactants. The generated particles indicated that a wurtzite structure of ZnO in a hexagonal phase was formed with a crystalline size that increased as the ultrasound irradiation time increased. The morphology of the generated ZnO particles could be changed from flowerlike to needlelike structures via continuous ultrasound irradiation over one to two hours, resulting in increases in the particle lengths and decreases in the particle diameters from 200 to 80 nm. Photoluminescence intensity was also increased with increases in the ultrasonic irradiation times. Photoluminescence spectra were also influenced by the atmospheric environment. Two bands centered at 390 and 500 nm were generated under a nitrogen environment. On the other hand, a single wide band with a peak at around 430 nm was found for particles generated under an air environment. It can be applied for light emitting diodes (LED) or laser fabrication with a controlled emitting band.

Abstrak :
This paper presents an investigation on the method for synthesizing hematite nanoparticle using ultrasonic sonochemistry. The effect of various bases with different basicity strengths, i.e. NaOH, NH4OH, and butylamine, as well as sintering treatment on the purity and crystallinity of hematite nanoparticles was studied. In this work, the as-synthesized hematite nanoparticles were characterized using FTIR, XRD, and HR-TEM analyses. The results showed that the formation of hematite crystal can undergo two possible reaction pathways depending on the basicity of the solution. When strong bases like NaOH and butylamine were used, iron(III) ion could react with water to form iron complexes, which further grow into rod-like magnetite nanocrystals as the major product. However, direct reaction of iron(III) ion with hydroxide ion to form hematite was observed when a weak base like NH4OH was used. Furthermore, it was also found that most of the polymorphous iron oxide precursors can be transformed into hematite crystals via high-temperature sintering.

Abstrak :
Single phased SrO.6Fe2-xMnx/2Tix/2O3 (x = 0.0; 0.5; and 1.0) nanoparticles, whose mean size was comparable with the crystallite size, were successfully fabricated through mechanical alloying and a subsequent ultrasonic destruction processes. The ultrasonic destruction process employed a transducer operated under amplitudes of 35, 45, and 55 ?m. Results indicated that the mean particle size was not determined by the transducer amplitude, but the mechanical properties of the materials, as well as the initial size of the particles. After ultrasonic destruction, the mean sizes of the particles decreased to the range of 87–194 nm with a narrow distribution width. The mean particle sizes were about 1 to 3 times larger than the respective crystallite sizes. Such fine particles were aimed to decrease the coercivity, as was seen in the sample with x = 0, which showed a decrease in coercivity from 474 kA.m-1 to 24 kA.m-1 and 15 kA.m-1. A further reduction in the coercivity was observed in Mn-Ti substituted strontium hexaferrite.

Abstrak :
Minyak atsiri merupakan senyawa penting dalam bahan alam, yang memiliki banyak khasiat bagi kesehatan manusia. Minyak atsiri dapat diambil dari bahan alam dengan proses ekstraksi. Salah satu proses ekstraksi yang sedang menjadi tren penelitian adalah ekstraksi ultrasonik, yang dinilai memiliki banyak keunggulan, seperti kemudahan operasi, energi yang relatif rendah, dan operasi pada temperatur rendah yang dapat menjaga stabilitas senyawa biokimia dalam bunga telang. Salah satu kebaruan dalam penelitian ini adalah adanya penambahan mekanisme probe yang bergerak secara oksilasi, memungkinkan sumber gelombang ultrasonik menjadi dinamis. Selain itu, juga ditambahkan variasi intensitas ultrasonik sebagai parameter optimasi universal dalam ekstraksi ultrasonik. Adapun metode yang digunakan dalam analisis adalah metode kuantitatif dengan pengukuran data-data temperatur dan perhitungan fraksi massa minyak atsiri sebagai representasi kuantitas minyak atsiri, metode kualitatif dengan analisis visual perubahan warna emulsi dan distribusi temperatur terhadap waktu, serta metode analitik dengan perhitungan kinetik proses ekstraksi ultrasonik, untuk mengetahui nilai yield, yang direpresentasikan oleh kuantitas senyawa phenolic dengan perhitungan konstanta Peleg. Hasil penelitian menunjukkan bahwa, dengan penambahan probe oksilasi, dapat menyeragamkan distribusi temperatur dan ikatan antara pelarut dan senyawa biokimia dalam bahan alam, atau dengan kata lain, meningkatkan kualitas minyak atsiri yang dihasilkan. Di sisi lain, intensitas ultrasonik yang semakin tinggi dapat meningkatkan volume minyak atsiri yang dihasilkan, yang direpsentasikan fraksi massa minyak atsiri dan analisis kinetik yield terhadap waktu, serta meningkatkan laju ekstraksi yang terlihat dari analisis kinetik dan perubahan warna emulsi terhadap waktu. Hal ini disebabkan karena intensitas ultrasonik meningkatkan efek sonokemistri, kavitasi, turbulensi dan tegangan geser yang meningkatkan kuantitas dan laju ekstraksi. Hal penting yang harus diperhatikan dalam optimasi proses ekstraksi ultrasonik adalah turbulensi yang terlalu tinggi dapat menyebabkan agitasi dan temperatur yang terlalu tinggi dapat berpotensi merusak senyawa biokimia aktif dalam bunga telang. ......Essential oil is an important compound in natural substances, which has many benefits for human health. Essential oil can be produced from natural substances through the process of extraction. One of the trending extraction processes is ultrasonic extraction, which is considered to have many advantages, including, ease of operation, relatively low energi consumption, and capability to operate at low temperature which keep stabilitizing biochemical compounds inside natural substances, which in this research used butterfly pea flower (Clitoria Ternatea L). The novelty of this research was the application of a mechanism of osscilating moving probe, enabling ultrasonic wave source to be dynamic. Additionally, varieties of ultrasonic intensities was also applied as an universal parameter in optimizing the process of ultrasonic extraction. The methods used in the research were quantitative methods by measuring data of temperatures and calculating essential oil mass fraction, as representatives of essential oil quantity, qualitative methods by visual analysis of emulsion color evolution and temperature distribution through time, as well as analytical method by calculating the kinetics of ultrasonic extraction process, to determine yield, represented by phenolic compound quantity with Peleg’s constant calculation. The results of the research showed that oscilating probe addition could evenly distribute temperature and enhanced the bonds between solvent and biochemical compounds inside the natural substances, in other words, improving the quality of essential oil produced. On the other hand, a rise in ultrasonic intensities could increase essential oil volume produced, which was represented by essential oil mass fraction and kinetic analysis of yield through time, as well as increasing the extraction rate, as shown in kinetic analysis and emulsion color evolution. This was due to higher ultrasonic intensities enhanced sonochemistry effect, cavitation, turbulence and shear stress which increased essential oil quantity and the rate of extraction process. The important issues that needed to be considered in optimizing ultrasonic extraction process was over turbulence which could cause agitation and overhigh temperature which potentially could damage the active biochemical compounds inside butterlfy pea flower as a natural susbtance.