Physics

This study aims to propose a risk analysis framework using the FMEA method and system dynamics approach. FMEA is used as a first stage to identify critical equipment/ system based on the highest RPN, then uses the value of the O (Occurrence) as an input to simulate the extent of the effectiveness of the costs incurred and to see the possibility of a decrease in critical system failure occurrences from time to time. The simulation carried out using a system dynamic approach by constructing a structural model of non-linear variables (cause-effect relationships) and considering the system boundary associated with risk management. With this modeling framework, it is expected that the various mitigation actions expected can be simulated with this modeling framework, and policy instruments related to risk management on the identified critical equipment can be evaluated to reduce the failure occurrences. In this paper, the proposed approach will apply to analyze various scenarios of risk m...

The use of aluminum trihydroxide (ATH) fillers as non-halogen flame retardants for polymethylmethacrylates (PMMA) creates a conflict between the mechanical properties and heat resistance of the composites. Therefore, to ensure that the PMMA mechanical properties remain satisfactory, improvements in both the filler–polymer interactions and the ability to control the size and size distribution, morphology and dispersion of the fillers are required. Thus, in the present study, bead milling was used to control both the size distribution and dispersion of ATH fillers in MMA, which had an initial average size of 0.75 μm. The dispersion was obtained by alteration of the surface characteristics of ATH fillers using a silane-based dispersing agent, (3-acryloxypropyl) trimethoxysilane (APTMS). Bead milling successfully comminuted the ATH particles and prevented the formation of ATH agglomerates. The smallest average size of the ATH particles after bead milling was 300 nm. Highly dispersed ATH filler particles were observed in the TEM images of the PMMA/ATH composites. The filler–polymer interaction, i.e. the interaction parameter (B), was calculated. The effects of volume fraction, particle size distribution, and surface modification of the fillers on the results of dynamic mechanical analysis (DMA) are discussed. The thermal stability of the PMMA/ATH composites was also investigated using thermal gravimetric analysis (TGA).This paper describes the dispersion of submicron aluminum trihydroxide (ATH) in MMA via the bead milling method. A silane-based dispersing agent was successfully applied to change the surface state of ATH fillers and promote dispersion stability. As-prepared PMMA/ATH composite loaded with 10 wt.% fillers enhanced the storage modulus and the thermal stability properties of the PMMA/ATH composites.

We report the synthesis and characterization of ZnO nanoparticles prepared via pulse combustion-spray pyrolysis (PC-SP) at a high rate. Instead of using an ultrasonic nebulizer as the atomizer during PC-SP synthesis, a two-fluid nozzle was used to enhance the production rate. A high production rate was achieved by the use of a two-fluid nozzle, which efficiently generated droplets in large quantities, and by controlling the rate of precursor flow. ZnO nanoparticles were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectroscopy. The prepared ZnO nanoparticles were spherical and highly crystalline with an average size of 15.6 nm. In addition, high UV-light absorption and visible-light transparency properties were successfully obtained for a dispersion of ZnO nanoparticles in glycerol. The high UV-blocking capacity of the ZnO particle dispersion makes the dispersion potentially useful in cosmetic applications.

This paper presents the surface functionalization with silane coupling agents for dispersing and stabilizing hexagonal boron nitride (hBN) nanoparticle suspension in a water phase. Fine milling using 30 μm bead technology was utilized for the reduction of particle size, while dispersing agents with silane coupling agents were used for surface modification to enhance dispersion stability. A monodispersed hBN nanoparticle was obtained by controlling the processing parameters and by optimizing the dispersant dosage. The hBN nanoparticle suspension showed a high degree of dispersion stability with a zeta potential below −40 mV when (3-acryl-oxypropyl) trimethoxysilane (APMS) was used as the dispersing agent. Under optimal operation conditions for bead milling, the final average size of the particle distribution for the hBN suspension was 46 nm and 38 nm for 0.5 wt.% and 5 wt.% hBN, respectively. In addition, the surface characteristics, morphology, crystal structure and chemical composition of the hBN particles before and after bead milling were investigated to know the effect of bead milling. Finally, the surface functionalization mechanism that enhanced the stability of hBN nanoparticle dispersion by electrosteric stabilization was also proposed.► A fine bead mill technology was used for dispersing hBN nanoparticles. ► A monodispersed hBN nanoparticles suspension in a water phase was obtained. ► The (3-acryl-oxypropyl) trimethoxysilane (APMS) used as a dispersant. ► The surface functionalization with APMS attained suspension stability. ► The mechanism of surface functionalization with APMS was proposed.

In this paper, a new method is proposed for the decolorization of a yellow-hued suspension of rutile TiO2 nanoparticles in an organic solvent (diethylene glycol dimethylether). The presence of color has always been undesirable in a suspension of nanoparticles filler used for industrial needs, particularly for optical applications.A colorless suspension was achieved by irradiating well-dispersed TiO2 nanoparticles in an organic solvent with UV-light (λ = 254 nm) for 5 h. TiO2 nanoparticles of 1 and 5 wt.% were dispersed using a beads mill method. Trimethoxytrifluor(propyl) silane was used as a dispersant to achieve stability. The effect of the UV-light irradiation on the TiO2 nanosuspension was investigated by means of a Fourier transform nuclear magnetic resonance analyzer (FT-NMR). The dispersant was partially desorbed due to the interaction of UV light and the TiO2/dispersant complex. Thus, an enhanced transparency and the absence of color were obtained for well-dispersed TiO2 nanoparticles in an organic solvent.

ABSTRACT In this article, I shall describe my experience of developing instructional tools of course on Statistical Physics as well as the implementation of Instructional Technology. I shall discuss the approach I took, the difficulties I faced, and the experiences I drawn from this education experiment during teaching and learning process.

Telah berhasil dirancang bangung ray tracer pengujian cahaya LED yang mampu mengakuisisi data dan memvisualisasikan pola sebaran cahaya di permukaan LED. Alat tersebur dapat mengakuisisi data dengan resolusi 0, 5o di sekitar permukaan LED dengan rentang sudut 0-180o. Rancang bangun alat tersebut terdiri atas perangkat detektor, modul akuisisi data, motor penggerak sensor dan komputasi. Detektor yang digunakan adalah sensor LDR.

Jurang kesenjangan sering terjadi antara pengausaan pemrograman dan pengetahuan tentang piranti elektronik yan gdihubungkan ke komputer. Hal ini mengakibatkan terjadinya kesulitan dalam menggunakan teknik pemrograman yang digunakan untuk membaca suatu regirter yan gditugaskan spesifik untuk membaca piranti elektronik tertentu yang dihubungkan ke personal computer (PC), dalam hal ini akan diacu menggunakan IBM-PC.

Currently, the hatchery of shrimp in aquaculture faces many obstacles. Our research objective was to design and development of expert system to control the physical variable of the environment and feeding distribution. We have been successfully developing an expert system implemented on aquaculture of shrimp hatchery.

Abstract Penelitian dan pengembangan bahan luminisensi untuk aplikasi lampu hemat energi (SSL) telah dilakukan di Laboratorium Sistem Instrumentasi dan Pemrosesan Material Fungsional, Jurusan Fisika, Fakultas MIPA, Universitas Padjadjaran. Pengembangan tersebut meliputi pengembangan peralatan sintesis dan karakterisasi bahan, pengembangan metode pemrosesan bahan luminisensi, pengembangan bahan luminisensi, pengembangan model fisis dan pengembangan aplikasi bahan luminisensi.

Dalam tulisan ini dilaporkan studi efek jenis pelarut terhadap sifat optik, morfologi permukaan dan koefisien waveguide loss? gw dari pandu gelombang planar polimer MEH-PPV. Pandu gelombang planar dibuat dengan teknik spin-coating dari larutan polimer dengan pelarut toluen, kloroform dan THF.

This paper describes an innovative integrated micro flow cytometer that presents a new arrangement for the excitation/detection system. The sample liquid, containing the fluorescent marked particles/cells under analysis, is hydrodynamically squeezed into a narrow stream by two sheath flows so that the particles/cells flow individually through a detection region. The detection of the particles/cells emitted fluorescence is carried out by using a collection fiber placed orthogonally to the flow. The device is based on silicon hollow core antiresonant reflecting optical waveguides (ARROWs). ARROW geometry allows one to use the same channel to guide both the sample stream and the fluorescence excitation light, leading to a simplification of the optical configuration and to an increase of the signal-to-noise ratio. The integrated micro flow cytometer has been characterized by using biological samples marked with standard fluorochromes. The experimental investigation confirms the success of the proposed microdevice in the detection of cells.

α-Mangostin, a xanthone derivative from the pericarp of Garcinia mangostana L., has numerous bioactivities and pharmacological properties. However, α-mangostin has low aqueous solubility and poor target selectivity in the human body. Recently, nanoparticle drug delivery systems have become an excellent technique to improve the physicochemical properties and effectiveness of drugs. Therefore, many efforts have been made to overcome the limitations of α-mangostin through nanoparticle formulations. Our review aimed to summarise and discuss the nanoparticle drug delivery systems for α-mangostin from published papers recorded in Scopus, PubMed and Google Scholar. We examined various types of nanoparticles for α-mangostin to enhance water solubility, provide controlled release and create targeted delivery systems. These forms include polymeric nanoparticles, nanomicelles, liposomes, solid lipid nanoparticles, nanofibers and nanoemulsions. Notably, nanomicelle modification increased α-mangostin solubility increased more than 10,000 fold. Additionally, polymeric nanoparticles provided targeted delivery and significantly enhanced the biodistribution of α-mangostin into specific organs. In conclusion, the nanoparticle drug delivery system could be a promising technique to increase the solubility, selectivity and efficacy of α-mangostin as a new drug candidate in clinical therapy.

The productivity of vegetable crops is constrained by insect pests. The search for alternative insect pest control is becoming increasingly important and is including the use of plant-derived pesticides. Plant-derived pesticides are reported as effective in controlling various insect pests through natural mechanisms, with biodegradable organic materials, diverse bioactivity, and low toxicity to non-target organisms. An antifeedant approach for insect control in crop management has been comprehensively studied by many researchers, though it has only been restricted to plant-based compounds and to the laboratory level at least. Nano-delivery formulations of biopesticides offer a wide variety of benefits, including increased effectiveness and efficiency (well-dispersion, wettability, and target delivery) with the improved properties of the antifeedant. This review paper evaluates the role of the nano-delivery system in antifeedant obtained from various plant extracts. The evaluation in...

Reduction of tar concentration in biomass gasification with secondary plasma tar cracking unit remains a challenge to meet the requirement for clean syngas energy applications. Typically, the post-treatment of syngas to reduce the tar from an updraft fixed-bed reactor is using secondary plasma tar cracking unit. In this study, an additional trapping train was introduced as a mechanism to harvest byproducts of the tar decomposition process (byproduct carbon functionalized material or BCFM). The measurement in gravimetric and particle size distribution, supported by photoluminescent (PL) and Fourier transform infrared spectroscopy (FT–IR) of BCFM, were conducted to reveal the BCFM characteristic. The gravimetric analysis showed that the application of the secondary plasma tar cracking unit highly reduced the tar concentration. Similarly, the average particle size also decreased significantly. The peak emission spectra of the suspended BCFM particle under the plasma cracking treatment ...

Graphite oxide is widely use in renewable energy application such as solar cells, fuel-cells, battery electrodes, catalyst support, etc. This paper reports the preparation of graphite oxide from Indonesian natural graphite by sodium cholate intercalation. The enrichment process of as received graphite with carbon content of 60% was carried out by using acid leaching (HF) method. The enrichment process successfully obtained graphite with carbon content 95.61% with contaminant minerals observed by EDS were magnesium and aluminum. Purified graphite was then intercalated by sodium cholate at various concentration and sonication time. The XRD results shows that preparation with concentration of sodium cholate 2 Wt.% and sonication 10 hours formed a peak characteristic of graphite oxide at 2θ=15 0. In addition, the successful oxidation process designated by the C/O ratio of 15.75 observed from EDS and supported by the present of functional C-H and CO obtained from the FTIR observation. It is concluded that the graphite oxide successfully prepared by intercalation using sodium cholate and sonication.

Zircon sand is one of Indonesian natural resource that is potential to be used as composite filler. Natural zircon sand can be found in several places in Indonesia, i.e. Riau Islands, Bangka-Belitung, and the Borneo. Zircon sand contains zirconia compound; while ZrO2 is the oxide crystal of zirconia compound. The mechanical and esthetical supremacy of zirconia is the reason why the usage of zirconia as nanocomposite filler mixed with alumina and silica increases. Spray pyrolysis method was used to synthesized natural zircon sand of Indonesia with temperature variety of 400°C, 500°C and 600°C. Spray pyrolysis decomposed zircon sand into powder in nano-sized. Microstructure analysis conducted were SEM, EDS, and XRD. SEM analysis showed that the morphology of particle was spherical, uniform, and regular with size of 100-500nm. EDS and XRD showed best results at the temperature of 400°C. Analysis result of EDS indicated that the largest atomic percentage was owned by sodium with ratio o...

Helicoverpa armigera (Hubner) is one of a serious pest of horticulture in Indonesia. Helicoverpa armigera Nuclear Polyhedrovirus (HaNPV) has attracted interest for many researchers as a pest control for larvae of this species. Currently, we investigating the agrochemical formulations of HaNPV by introducing nanotechnology. Thus it is required an acceptable efficiency of insect stock cultures equipped with advance instruments to resolve the difficulties on insect stock seasons dependency. In addition, it is important to improve the insect survival with the aid of artificial natural environment and gain high insect production. This paper reports the rearing cabinet used as preparation of stock culture includes airconditioning system, lighting, i.e. day and night control, and the main principles on recent technical and procedural advances apparatus of the system. The rearing system was moveable, designed and build by allowing airconditioned cabinet for rearing insects, air motion and distribution as well as temperature and humidity being precisely controlled. The air was heated, humidified, and dehumidified respectively using a heater and ultrasonic nebulizer as actuators. Temperature and humidity can be controlled at any desired levels from room temperature (20°C) to 40 ± 1°C and from 0 to 80% RH with an accuracy of ± 3% R.H. It is concluded that the recent design has acceptable performance based on the defined requirement for insect rearing and storage.