<p class="Abstract">Pesticide residues in fruits and vegetables pose a danger to human health if consumed for a certain period. This requires appropriate technology for household scale and is environmentally friendly. Ozone is a strong oxidizing agent capable of degrading pesticide residues in fruits and vegetables. Ozone is a green chemical compound because it does not produce harmful derivative compounds, and is even friendly to the environment. The development of a mini ozone generator with DBD technology has been successfully carried out. The DDBD reactor is made of Pyrex glass with a length of 10 cm and an outer diameter of 4 cm. The reactor uses electrodes made of copper plates. The outer electrode is 13 cm long and 5 cm wide, while the inner electrode is 10 cm long and 5 cm wide. Optimization of the mini ozone generator is carried out using high voltage AC pulses whose pulse frequency can be varied from 30 to 60 Hz with 10 Hz intervals. The free air flow rate was varied at 0.2 – 0.8 lpm with an interval of 0.2 lpm. The optimum ozone production of 480 mg/l was obtained at a voltage setting of 2.8 kV and a frequency of 50 Hz and a flow rate of 0.2 lpm. In this setting, the DDBD reactor consumes 9.32 watts of power. The development of mini ozone generator technology has the potential to be applied on a household scale because of the small reactor size and low power consumption. </p>

<p>Refractive index is important parameter in various fields, such as environmental, chemical, industrial, and medical. Measurement of refractive index can be done using optical sensor based buried waveguide core offset. This research aims to fabricate and characterize core offset buried waveguide based on <em>Polymethyl Methacrylate </em>(PMMA). Fabrication of buried waveguide was done by creating a cladding of waveguide made from PMMA which has a refractive index of 1.4908 using computer numerical Control machine (CNC). The material used as waveguide core was unsaturated polyester resin (UPR). Characterization was performed to determine the spectrum of input intensity and output intensity. Characterization were done by dipping the waveguide sample in to a container containing glucose solution with concentration of 12%, 14%, 16%, 18%, 20%, and 24%. Waveguide was connected to Polymer Fiber Optic (POF). One of the of POF as an input is connected to light emited diode with wavelength of 470 nm and one of the end other POF as an output was connected to Spectrometer Ocean Optic USB4000. The result showed that the total loss at concentration of 12%-24% is -4.62 dB, -5,70 dB, -6,01 dB, -6,49 dB, -6,15 dB, -6,16 dB, respectively. Sensor works well at a solution concentration of 16%-20% with a sensitivity value of 19.62 dB/RIU and correlation factor of 92.76%.</p><p> </p>

<p>A research on neutron contamination in LINAC device has been carried out using a Monte Carlo method. The simulation is based on the Siemens Primus LINAC machine model whose component consists of target, primary collimator, flattening filter and secondary collimator as its main components. A neutron contamination examination was carried out using a 10 x 10 cm radiation field and a 100 cm SSD. Subsequently, at a distance of 100 cm from the X-ray source, a water phantom is placed. Investigation of the presence of contaminants was carried out the LINAC operating voltages of 6, 8, 10, 15, 18 and 25 MV. The simulation results show that neutron contamination occurs due to the interaction of photons with the components of the LINAC device, namely the primary collimator, flattening filter and secondary collimator. The operating voltages that can produce neutron contaminant start at 10 MV. Increase in the voltage of the LINAC device causes consequent increase in neutron flux. Such increase in neutron flux has the potential to increase therapeutic dose.</p>

<p class="AbstractText">Performance characterization of 450 nm visible light photoacoustic imaging has been carried out through phantom imaging of methylene blue (MB), methyl orange (MO), and methyl red (MR) dye solutions. The phantom was made of a nylon tube with a diameter of 5.0 mm (outside) and 4.6 mm (inside) having a height of 2.0 mm along with a 6×6 cm black galvanized aluminum plate as the background medium. The nylon tube was filled with each type of solution with varying molecular concentrations of 10, 25, 50 and 100 ppm. Twelve (12) phantom objects were imaged in an area of 10×10 cm. The visible absorption peak known from UV-Visible spectroscopy for each type of solution is at 664 nm (methylene blue), 465 nm (methyl orange), and 522 nm (methyl red). It was also known that the amplitude of PA emissions would increase proportionally to the concentration of dye molecules. Overall, methyl orange solutions had the highest photoacoustic emission amplitude distribution. The analysis showed that the ratio of inner diameter (ID) and wall thickness (WT) between the MB and MO phantom images to the original object were 1:0.83 and 1:0.74 (ID) and 1:3 and 1:1.5 (WT), respectively. On the other hand, the ratio of the outer diameter (OD) of the MR phantom image to the original object is 1:1.28. </p>

The structure and magnetic properties of Fe/Si nanoparticle prepared by high energy milling process have been examined, focusing on the phase transition. Fe/Si nanoparticles were processed by high energy milling (HEM) for 10 hours to 50 hours with a weight per cent ratio of 9:1. Based on the X-ray diffraction (XRD) pattern, transmission electron microscope (TEM) observations, and vibrating sample magnetometer (VSM) analysis, the phase transition induced by HEM, were evidenced. The effect of structural state and the particle size on the magnetic properties such as magnetization was also studied. It was found that iron and iron oxides (-Fe2O3/ Fe3O4) phase were exhibited on all milled samples. The magnetization value of Fe/Si nanoparticles increased up to 20 hours with 142 emu/gr saturated magnetization and then decreased linearly with increasing milling time. Referring to the XRD result, this decline was initially caused by the iron oxide formation and magnetic interaction between iron and iron oxides nanoparticles. The phase and magnetic properties value changes related to the interaction mechanism between Fe atoms caused by interstitial occupied of Si atoms, particle size reduction, and oxidation process.

<p class="AbstractText">Distribusi spasial dan temporal dari parameter seismisitas yang terdiri dari <em>magnitude of completeness</em> (Mc), <em>a-value</em>, dan <em>b-value </em>telah dihitung sebagai upaya untuk menganalisis tingkat kegempaan wilayah Jawa Timur. Parameter tersebut dihitung berdasarkan data katalog gempa bumi <em>International Seismological Center</em> (ISC) dalam rentang waktu antara tahun 1980-2020. Tujuan dari penelitian iniadalah untuk menentukan parameter seismisitas dan distribusi spasial dan temporalnya sehingga proses deteksi dan peringatan dini gempa bumi di Jawa Timur dapat berjalan secara optimal. Parameter seismistas dihitung dengan menggunakan metode <em>Maximum Curvature</em> (MaxC). Metode MaxC dalam menentukan parameter seismisitas terdiri dari proses menentukan titik kelengkungan maksimum dengan menghitung nilai maksimum dari turunan pertama kurva distribusi Frekuensi-Magnitudo (FMD). Variasi parameter seismisitas kemudian dipetakan secara spasial dan temporal setiap sepuluh tahun dalam kurun waktu 50 tahun terakhir untuk melihat perubahan variasi parameter seismisitas. Hasil penelitian menunjukkan Mc-<em>value</em> 3,4 – 4,8; a-<em>value</em> 5,560 - 8,244; dan b-<em>value</em> (0,73 – 0,82 ± 0.13). Daerah yang memiliki <em>b-value</em> rendah (0,73 ± 0.13) berada di sekitar wilayah selatandai Jawa Timur. Wilayah ini diindikasikan sebagai daerah dengan pelepasan momen seismik yang tinggi dan memiliki akumulasi tingkat <em>stress</em> batuan yang tinggi. Mengetahui dan memahami hubungan antara parameter seismistas dan struktur tektonik dapat membantu kita untuk menentukan tingkat resiko bencana gempa bumi di wilayah Jawa Timur.</p>

Paroxysmal Atrial fibrillation (PAF) is a heart problem relating to irregular and rapid beating of the heart atria. It has risk of stroke and is independently associated with risk of mortality. Early information of PAF episode is important for a patient to have appropriate treatment to reduce atrial fibrillation complications. This article presents a new strategy to detect PAF with base of statistical electrocardiographic features and a support vector machine (SVM). R-peak series of electrocardiogram were segmented and were extracted to find the statistics of RR intervals. Different approaches in relation with the segmentation were investigated. Two-class SVM with radial basis function (RBF) and the statistics of RR intervals were examined for PAF detection. Using clinical data of patients with PAF, the proposed strategy showed excellent performance of 99.17% in terms of accuracy. The experimental result indicated that the appropriate statistics of RR intervals and SVM-RBF with its suitable parameters can perform well for PAF detection.

Thermoplastic and thermoset polymer composites reinforced with kenaf fiber or CaCO<sub>3</sub> have been extensively investigated. However, the study on the combination of kenaf fiber and CaCO<sub>3</sub> reinforced epoxy resin is rare. This research discussed the effect of CaCO<sub>3</sub> particle size and the ratio of kenaf to CaCO<sub>3</sub> content on the impact strength of alkali-treated kenaf/ CaCO<sub>3</sub>/epoxy resin hybrid composites. Thirty % of the hybrid kenaf fibers and CaCO<sub>3</sub> particles reinforced epoxy resin composites were fabricated by hand lay-up technique followed by cold press. Impact test of the composite specimens was conducted using a Charpy Impact test according to ASTM D 6110. The morphology of impact fracture surface was examined by scanning electron microscopy (SEM). The results showed that the impact strength of the hybrid composite increased with the decrease of CaCO<sub>3</sub> particle size, and increasing the ratio of kenaf to CaCO<sub>3</sub>. Interfacial bonding between the reinforcement (kenaf and CaCO<sub>3</sub>) and epoxy resin matrix, the uniform dispersion of kenaf and CaCO<sub>3</sub> within the epoxy resin matrix are two crucial factors influencing the impact strength of the composite.

<p>Air menempati suatu wadah rongga di dalam tanah yang disebut dengan akuifer. Salah satu akuifer yang masih jarang digunakan adalah akuifer tertekan. Akuifer ini terletak lebih dalam, sehingga keberadaan perlu dideteksi lebih dahulu. Untuk mendeteksi keberadaan akuifer menggunakan metode geolistrik resistivitas. Alat yang digunakan adalah resistivitimeter OYO Model 2119C McOHM-EL, dengan konfigurasi Schlumberger dengan bentangan AB/2 samapai 350 meter. Pengambilan data dilakukan di Kecamatan Plupuh Kabupaten Sragen sebanyak 5 titik sounding. Pengolahan dilakukan dengan menggunakan software IP2win.</p>Hasilnya menunjukkan bahwa lapisan akuifer di 5 titik sounding berupa lapisan pasir lempungan, pasir dan lapisan pasir kerikilan. Lapisan akuifer tertekan terdeteksi di: TS1 pada kedalaman 39,9 meter- 110 meter dengan litologi pasir kerikilan, TS2 pada kedalaman 40,25 meter – 66,58 meter dan 80,24 -139,7 meter dengan litologi pasir, TS3 pada kedalaman 47,25 meter – 101 meter dengan litologi pasir lempungan,TS4 pada kedalaman 40,72 meter – 103 meter dengan litologi pasir lempungan dan TS5 pada kedalaman 31,41 meter – 97 meter dengan litologi pasir lempungan.

<p>The geophysics test using electrical resistivity method has been conducted in the area of UNS Campus to indicate the lithological of subsurface. This method is categorized as a Non-Destructive Test (NDT) due to the data acquisition is done at the ground level and no destruction during the test, which is more advantageous than destructive method such as drilling and SPT test. This study was performed with Schlumberger configuration in three location by electrical resistivity sounding. The acquisition data uses Resistivity meter OYO 2119 McOHM-EL with the track length is 100 m, while the data processing use IPI2Win to get a logarithmic graph between distance and resistivity and Origin to obtain graphic of resistivity and SPT. The result of this study indicates that electrical resistivity has a good correlation with SPT data. The electrical resistivity graph shows a linear increase along with increment of the depth, which is similar to the SPT graph. The slope difference at the first location is 2.44±1,197, the second location is 2.028±0.822, and the third location is 0.622±0.735.</p>