[en] TiO₂ (titania) has a good potential for photocatalytic activity in degrading the bacteria by attacking the membrane with OH radicals, inhibiting the synthesis of proteins and nucleic acids in bacteria, the OH radicals can be a strong oxidizing agent activated by light irradiation. We investigate the antibacterial activity of Titania anatase in reducing bacterial colonies. Titania powder was deposited on polypropylene by spray method. The formed film was then the heated on the hotplate at 70°C. Antibacterial test was performed using the plate counting method. Principally, the Plate Count Method calculates the number of colonies formed on each plate. Plate Count Method is carried out by dissolving test samples containing bacteria with physiological salt water. Before dissolving, one piece of each sample that has been irradiated under the light for 24 hours was taken. This experiment shows good result of bacteria degradation. Technical grade Titania from Bratachem showed the performance almost the same as nano or pure titania did. The Technical grade titania has potential for large scale application . (paper)

[en] Evanescent wave is the result of Attenuated Total Reflection (ATR), Surface Plasmon Resonance (SPR) occurs at a specific angle on condition ATR. When a beam is passed through a prism, the beam will experience a reflection on the part of the prism which is in contact with the sample. The result of this reflection to be captured by the detector, On the condition of SPR weaken the intensity of the reflected beam of laser light that occurs because the refracted exponentially away from the boundary of the medium. The LabVIEW-based program has been created that can be used as a tool for experimental SPR, using Motor SHOT 602 and Lock-In Amplifier (SR510). Programs that have been made already equipped with the condition automation starts of movement Motor 2 (Prism), Motor 1 (Detectors), Readings Voltage detectors by Lock-In Amplifier (SR510) and storage of results (time, a position of the motor 1 and 2, the voltage read Lock in Amplifier). Automation program is made by studying the way of the light at Surface Plasmon Resonance (SPR), to determine the relationship between the rotational angle of motor prism and the rotational angle of motor, it can be used for control the position of the sample on the prism and the detector in a program based on LabVIEW. (paper)

[en] An electrified nickel wire can produce heat. The heat is transferred to the environment around the wire radiation. However, the temperature produced by the wire will differ depending on the number of voltages supplied by the power source. Here, we do an experiment to measure the temperature of stand-up wire at each voltage of 4.5 V, 6.0 V, 7.5 V, 9.0 V, and 12 V. As a comparison, numerical measurements are done by JavaScript program. We show that the highest temperature of the wire approaches 314 K at 12 V. To equalize the temperature in both methods, the numerical scale factor of time and current in numerical measurements are changed according to the voltage. As a result, temperatures produced in both methods have minimal gap difference with error percentage below 0.5%. In conclusion, the experiment results were used to determine the scaling parameters to approach the ideal thermal response curve in actual values. (paper)

[en] Indonesia has great potential of the Solar energy, irradiated by the Sun throughout the years. Cotton textiles antibacterial has been prepared by coating Titania (TiO₂) with Polyethylene glycol (PEG) and Polyvinyl alcohol (PVA) as adhesives. The method of depositing cotton using a simple dip coating. Cotton dry for 15 minutes with a halogen lamp, after the deposition process. Then, we do the antibacterial activity test using Plate Count Method. As a result, the coated cotton textiles with Polyvinyl alcohol (PVA), Polyethylene glycol (PEG) has antibacterial properties. Characterization by the Attenuated Total Reflectance (ATR) obtained that Titania (TiO₂) surely adhere on the sample. From Attenuated Total Reflectance (ATR) characterization we conclude that Polyvinyl alcohol (PVA) and Polyethylene glycol (PEG) is not affecting the antibacterial ability of Titania (TiO₂). But the infusion of Polyvinyl alcohol (PVA) and Polyethylene glycol (PEG) on Cotton increases the stiffness value of Cotton. (paper)

[en] Tortuosity is an important physical property in porous materials since it describes path length of fluid through the materials, which means how much the loss of kinetic energy. The simplest definition of tortuosity T is λ/L with λ is length of the path and L is the distance between two ends of the path. System is discretized using grid to limit number of possible paths, which could be infinity for continuous system. Porosity of the system is also constrained. Variable T is chosen as macrostates in statistical physics point of view, while all possible paths within this T are the microstates. It is found that some macrostates (more appropriately is its maximum value) have larger thermodynamics probability than the others. It should be a relation between this probability and reported tortuosity. (paper)

[en] There are many models and calculation techniques to obtain visible image of fission yield process. In particular, fission yield can be calculated by using two calculations approach, namely macroscopic approach and microscopic approach. This work proposes another calculation approach in which the nucleus is treated as a toy model. Hence, the fission process does not represent real fission process in nature completely. The toy model is formed by Gaussian distribution of random number that randomizes distance like the distance between particle and central point. The scission process is started by smashing compound nucleus central point into two parts that are left central and right central points. These three points have different Gaussian distribution parameters such as mean (μ_CN, μ_L, μ_R), and standard deviation (σ_CN, σ_L, σ_R). By overlaying of three distributions, the number of particles (N_L, N_R) that are trapped by central points can be obtained. This process is iterated until (N_L, N_R) become constant numbers. Smashing process is repeated by changing σ_L and σ_R, randomly

[en] The aim of this work is to characterize the modes of motion of pseudo-two dimensional granular materials in a vertical rotating drum. The granular materials are 4 mm diameter marbles, which are put in a flat drum with 16 cm diameter and 5 mm thickness. Rotation axis of the drum is always perpendicular to the direction of gravity. Granular materials in a vertical rotating drum usually have six modes of motion i.e. slipping, slumping, rolling, cascading, cataracting, and centrifuging. Those modes depend on number of granular particles, rotation speed, and types of materials of granular particles. Characterization of modes of motion in this work has been conducted by varying number of particles, rotation speed, and types of materials. Rotation speed is varied from 15 rpm to 125 rpm, while number of granular material is varied from 50 to 600. Each steel and plastic granular materials has five modes of motion with centrifuging mode is absence in observation of steel materials and slipping mode is absence in observation of plastic materials, both for the same parameter ranges used in the experiments. Parameters room of number of particles against rotation speed for both types of materials are presented. (paper)

[en] Molecular dynamics in 2-D accompanied by granular model provides an opportunity to investigate binding between nuclei particles and its properties that arises during collision in a fusion reaction. A fully classical approach is used to observe the influence of initial angle of nucleus orientation to the product yielded by the reaction. As an example, a simplest fusion reaction between ₁H² and ₁H³ is observed. Several products of the fusion reaction have been obtained, even the unreported ones, including temporary ₂He⁴ nucleus.

[en] Dynamics of pseudo-two dimensional granular material consisted of two layers cylinder piles positioned on top of a horizontally vibrated plate is reported in this work. It is aimed to observe structural change of the cylinder pile vibrated in certain frequency and amplitude. Dimensionless acceleration Γ= 4π₂f₂A/g (with g is gravitational acceleration), which is generally used in granular materials to observe transition between states, e.g. stable, rotating without slipping, rolling and slipping in Γ-f plane, does not work well for this system. For this system additional states for the piles can also be observed, e.g. stable and flowing states. Observations parameters are frequency f (measured in Hz) and amplitude A (measured in cm). These parameters are used to construct the A-f plane instead of Γ-f one. (paper)

[en] Several two-dimension spherical particles are under influence of gravitational forces of each other and as they are colliding repulsion forces in form of linear spring-dashpot prevent them from collapsed into a single point. Gravitational constant larger than G is used for better and faster stabilization in forming cluster of the particles, accompanied with values of k_N ≈ 10⁴ N/m and yn ≈ 0.5 N·s/m As initial conditions the particles are placed randomly with separation distances among each other. Molecular dynamics method implementing Euler algorithm is used to simulate the developing of particles cluster, which is intending to mimic the process of an asteroid forming. Time step of Δ t = 10² s is chosen and results are reported every some period from 1 s to 1000 s, where after each period all particles velocity are forced to be zero. It is observed that not only physical parameters influencing the compaction of the asteroid but also simulation parameters. (paper)