Time filter

Source Type

Surakarta, Indonesia

Muhammadiyah University of Surakarta is one of 164 Universities of Muhammadiyah and one of the 1890 Private Higher Educational institutions in Indonesia. Charity business education is determined to create a campus that promotes "Scientific and Islamic Discourse" to foster an Islamic culture that will instill in its students, knowledge and skills based on Islamic values. Wikipedia.

Widayatno T.,Muhammadiyah University of Surakarta
AIP Conference Proceedings | Year: 2015

Electrodeposition of nickel onto copper in a system of low Ni2+ concentration and at a narrow interelectrode gap has been carried out. This electrochemical system was required for maskless pattern transfer through electroplating (Enface technique). Kinetics of Electrochemical reaction of Nickel is relatively slow, where such electrochemical system has never been used in this technology. Study on the kinetics of the electrochemical reaction of nickel in such system is essential due to the fact that the quality of an electrodeposited nickel is affected by kinetics. Analytical and graphical methods were utilised to determine kinetic parameters. The kinetic model was approximated by Butler-Volmer and j-η equation. Kinetic parameters such as exchange current density (j0) and charge transfer coefficient (α) were also graphically determined using the plot of η vs. log|j| known as Tafel plot. The polarisation data for an unstirred 0.19 M nickel sulfamate solution at 0.5?mV/s scan rate and RDE system was used. The results indicate that both methods are fairly accurate. For the analytical, the Tafel slope, the exchange current density, and charge transfer coefficient were found to be 149?mV/dec, 1.60 × 10-4 mA/cm2, and 0.39 respectively, whilst for the graphical method were 159?mV/dec, 3.16 × 10-4 mA/cm2, and 0.37. The kinetics parameters in this current study were also compared to those in literature. Significant differences were observed which might be due to the effect of composition and concentration of the electrolytes, operating temperature, and pH leading to the different reaction mechanism. However, the results obtained in this work are in the range of acceptable values. These kinetic parameters will then be used in further study of nickel deposition by modelling and simulation. © 2015 AIP Publishing LLC. Source

Sutrisna E.M.,Muhammadiyah University of Surakarta
Asian Journal of Pharmaceutical and Clinical Research | Year: 2015

Rifampicin is one of the first-line anti-tuberculosis drugs. Rifampicin is metabolized by cytochrome P450 (CYP) 3A4. Polymorphisms of the CYP3A4 gene will affect gene expression. This leads to impaired of formation of the enzyme. The purpose of this review is to explore the effect of self-induction of Rifampicin. The results of this review showed that Rifampicin was metabolized by the CYP3A4 enzyme. Rifampicin has self-induction properties since Rifampicin also induces CYP3A4 enzyme. Rifampicin treatment repeated for 14 days leads to a shortening elimination half-life. Self-induction of CYP3A4 by Rifampicin maximum is reached after 21 days of use. Bioavailability of Rifampicin decreased from 93% to 68% after 3 weeks of treatment single dose orally. After 7 days administration of Rifampicin will increase clearance but decrease the area under the curve and Cmin. The effect of autoinduction of Rifampicin is estimated occurs after the first 6 days of administration. In individual with the variant type of CYP3A4 namely CYP3A4*1G/*1G, the effect of self-induction of Rifampicin is minimal. © 2015, Asian Journal of Pharmaceutical and Clinical Research. All rights reserved. Source

Sarjito S.,Muhammadiyah University of Surakarta
Applied Mechanics and Materials | Year: 2013

Downdraft evaporative cooling systems can be used for the thermal management of inside spaces in hot dry environments. There may be scope for improvement of such systems. The work described here is a study aimed at validating the Computational Fluids Dynamics (CFD) method using experimental data available from a prototype multi-stage system which existed at Ben-Gurion University. A detailed model of the prototype device has been developed. Initial CFD work has focused on establishing the relationship between ambient wind speed and the downdraft flow rate and comparing the result with the existing experimental data. Initial results are consistent and encouraging. Detailed flow features not evident from the experiments are revealed. Further CFD work to model the prototype performance with water spray evaporation is described briefly. © (2013) Trans Tech Publications, Switzerland. Source

Ulinuha A.,Muhammadiyah University of Surakarta
ARPN Journal of Engineering and Applied Sciences | Year: 2016

Distribution system is a part of electrical system that suffering from a number of problems, such as load variation, voltage fluctuation, and harmonic distortion. Harmonic distortion is one of the concerns recently taking more attention since it may cause losses amplification, rms voltage increment, and, the most dangerous effect is, equipment destruction if resonance frequency occurs. The extensive use of devices generating harmonic frequencies is the main reason of the problem. The nonlinear v-i characteristic of the devices may result in distortion of system voltage that should be prevented not to spread and further deteriorate the system. For this purpose, harmonic filter is commonly installed in the system. Distribution system normally includes a number of shunt capacitors for voltage improvement and losses minimization. However, the capacitors may also amplify the distortion. In this paper, the location and size of harmonic filters is determined using Genetic Algorithm. The aims are to improve the voltage and minimize the losses while mitigating the distortion. The implementation on the IEEE 18-bus system indicates simultaneous system enhancements including voltage improvement, losses reduction, and harmonic mitigation with minimum system modification and cost requirement. © 2006-2016 Asian Research Publishing Network (ARPN). Source

Widayatno T.,Muhammadiyah University of Surakarta
ARPN Journal of Engineering and Applied Sciences | Year: 2016

Thickness and morphology of electrodeposited coating is crucial in every application of protective finish to ensure high quality and performance is achieved. How a deposited metal is distributed across the cathode surface is greatly affected by current density distribution. To calculate current density distribution prior to the design of electrochemical system is essential in order to optimize the uniformity. The effect of cell geometry and kinetics on current density distribution in nickel electrodeposition from low electrolyte concentration and narrow interelectrode gap has been investigated. This electrochemical system was required for nickel pattern transfer using Enface technology. The modelling and simulation was carried out by solving Laplace's equation in the potential model theory considering appropriate boundary conditions using the Boundary Element Method. The simulation was accomplished by using software of Elsy (ELSYCA NV). The results show that the current density distribution using 2D and axy-symmetrical system was identical for all electrode sizes. However, current density at the electrode edge in the axy-symmetrical model was higher by around 19 % which might be due to the extra space around the electrode. Thus, 2D configuration was sufficient to represent the actual reactor geometry for the experimentation. In a parallel plane electrode configuration, the current density significantly increases at the edge of the cathode. The current density was uniform in the range of 0.08< x/L (normalized length) < 0.92 which was over 80% of the surface area. Therefore, the patterns should be located at the middle of the anode for ensuring a uniform thickness of deposited nickel pattern was achieved. © 2006-2016 Asian Research Publishing Network (ARPN). Source

Discover hidden collaborations