Chomsin S. Widodo

A study of application of two probes at frequency 0.1 to 10 kHz in electrical impedance measurement system for various fats

Measurement of electric impedance by using two probe methods applied to various types of fat. This study is a development of previous research that performed fat impedance measurements at very low frequencies using LCR meter. In the analysis of the liquid medium, the two probe models may indicate a change in electrical properties of the material when the material contains a different liquid medium. The content of fatty acid saturated and unsaturated in fat will determine the electrical properties of the material. In this study, we will describe two probe-based electrical impedance measurements rather than mixtures of various dietary fats by applying a current of 1 μA at a frequency of 0.1 kHz to 10 kHz. Food fats used research such as lard, beef fat, chicken fat and vegetable oil. The results showed that, in general, the electrical impedance of fat decreased with the increasing of measurement frequency. The electrical impedance of chicken fat is smaller than the lard, while beef-fat, and vegetable oils are bigger than it. The impedance meter worked well at frequencies up to 2 kHz. The presence of a mixture of the lard will change the value of electrical impedance in different fats.

Timing management for acquisitions of AC voltage and current signals using an AVR microcontroller based system

Acquisitions of alternating voltage and current signals are widely implemented whether for monitoring or control applications. Precise timings during the acquisitions of the signals are needed to attain appropriate consecutive sampling of the signals. This paper presents a technique to manage the acquisition timings so that the sampled AC voltage and current signals can be further processed such as determining the power and their harmonic contents. The voltage and current signals were consecutively acquired through the use of a voltage transformer and a current transducer. In the developed technique, the timing management is supported by the implementation of some peripherals inside an AVR microcontroller and interrupt mechanisms. The software for the microcontroller was developed to control the implemented hardware and perform calculations to get important parameters such as RMS voltage and current, power, and harmonic contents. Some experimentations were carried out by acquiring the signals with 256 samples and sending the results to a computer to be analyzed. The results showed that the technique could successfully manage the timings for acquiring the ac signals precisely. The use of the interrupt mechanisms could also avoid timing disturbances which could be caused by tasks which were not related to the acquisition processes and executed by the microcontroller.

Electrical Impedance Value Analysis on Formalinized Tilapia Fish Meat

Electrical impedance can be used as a non-destructive method to determine the bio-electrical characteristics on biological materials. Analysis of the electrical impedance value by using an electrode needle method has been applied to the tilapia flesh which aims to determine the bio-electrical characteristics on tilapia flesh, and determine the effect of formalin on it. The measurements were carried out to compare the characteristics of bio-electrical characteristics of the fresh tilapia flesh, the tilapia flesh soaked in formalin, and the one that was lay without any preservation treatment at a 10 Hz - 200 kHz frequency. The result shows that the impedance value characteristics of the fresh tilapia flesh decreased as long as the increase of frequency. Both the preserved and the rotten tilapia flesh have the decreased impedance value. The concentration of formalin immersion is directly proportional with the value of electrical impedance.

Pengaruh Radiasi Gamma dan Ekstrak Temulawak (Curcuma xanthorrhiza) terhadap Kadar SGPT Hepar Mencit (Mus musculus)

Gamma radiation can causes cells damage, because the interaction between radiations with cells can produce free radical. The compound that can neutralize and catch free radical is called antioxidant. The objectives of this research were to analyze influence of gamma radiation and Curcuma xanthorrhiza extract to the SGPT level to the mice’s liver. This research uses eighty mices and they were divided into three group, negative control (K-), radiation non extract (R-) and extract plus radiation (R+). The doses of treatment of Curcuma xanthorrhiza extract are 1,4 gr/kg body weight; 2,0 gr/kg body weight; 2,6 gr/kg body weight; 3,2 gr/kg body weight and 3,8 gr/kg body weight, while the exposure of gamma radiation are given during 10 minutes, 20 minutes, 30 minutes, 40 minutes and 50 minutes. The measuring of SGPT level in mice’s serum is done by using blood analyzer. The results showed that free radical can damages liver cells and breaks cell wall, so SGPT level in blood to be high. In a row of increasing of Curcuma xanthorrhiza extract dose, then SGPT level to be low.