Analisa Penambahan Aluminium (Al) terhadap Sifat Hidrogenasi Paduan Mg2-xAlxNi Hasil Sintesa Mechanical Milling dan Heat Treatment

Hydrogen storage merupakan salah satu kunci dalam pengembangan sumber energi hidrogen (H2) komersil. Magnesium diketahui memiliki kapasitas penyimpanan hidrogen yang relative cukup tinggi 7,6%. Dalam penelitian ini, dilakukan sintesa Mg2-xAlxNi dari serbuk Mg, Al, dan Ni dengan mechanical milling dengan variasi Al (x = 0;0,1;0,25;0,5) dengan kecepatan 400 rpm dan BPR 10:1 selama 10 jam dalam lingkungan argon. Kemudian di heat treatment pada temperatur 385oC selama 10 menit. Kemudian dilakukan proses hidrogenasi pada temperatur 250oC dengan lingkungan hidrogen (H2) bertekanan 5 bar. Pada proses mechanical milling dan heat treatment belum mampu menghasilkan paduan intermetalik Mg2Ni, namun seiring dengan penambahan aluminium pada proses heat treatment berhasil mereduksi Mg(OH)2. Pada proses hidriding berhasil membentuk fasa hidrida metal MgH2, yang menyatakan bahwa hidrogen berhasil diserap oleh paduan. Dilanjutkan dengan proses annealing pada temperatur 600oC pada lingkungan nitrogen (N2), dan pada proses ini berhasil membentuk paduan intermetalik Mg2Ni, MgNi2 dan Mg3AlNi2, namun pada proses hidriding belum bisa membentuk fasa hidrida metal kecuali pada komposisi x=0,1 dan x=0,

Pengaruh Senam Poco-poco Terhadap Kadar Kolesterol High Density Lipoprotein Darah

: High Density Lipoprotein (HDL) is denser than other types of cholesterol. Blood HDL cholesterol protects the inner wall (endothelium) of blood vessels. Exercise such as Poco-poco dance can increase the HDL cholesterol level. This study aimed to obtainthe the effect of Poco-poco dance on blood HDL cholesterol level. This was an experimental study with one group pre and post test design. Subjects were 25 Pharmacy female students, Faculty of Mathematics and Sciences, Sam Ratulangi University. Subjects were selected by purposive sampling method. Data were analyzed by using paired T test. The results showed that the average of blood HDL cholesterol level of subjects before training was 57,76 mg/dL and increased to 58,44 mg/dL after 4 weeks of training. The statistical analysis showed a p value >0.05. Conclusion: There was no statistically significant increase in HDL cholesterol level after 4 weeks of Poco-poco dance

Penentuan Nilai Sun Protective Factor (SPF) Secara in Vitro Krim Tabir Surya Ekstrak Etanol Kulit Alpukat

Peel of avocado (Persea americana Mill) contain efficacious compounds as an antioxydant.This studyhave purpose to determinethe value of Sun Protective Factor (SPF) of sunscreenfrom avocado's peel extract (Persea americana Mill) with aconcentration of5%, 7.5% and10%. In the determination of in vitro SPF valuesusing a spectrophotometer produce SPFvalues obtainedat a concentration of 5% is 3.99, 7.5% is 5.88,10% is 6.81. This study provesthat the use of this creamis notefficaciousas a sunscreen because the value result of SPF notexceed the minimal limit of good sunscreen SPF, that is 15

Studi Kasus Lingusql: Aplikasi Transaksi Perdagangan Saham

Proses pengembangan perangkat lunak yang ideal selalu mensyaratkan pengujian yang menyeluruh untuk memperoleh hasil perangkat lunak yang memiliki tingkat kebenaran tertentu. Namun pada prakteknya pengujian secara menyeluruh sangat jarang dilakukan karena membutuhkan sumber daya waktu dan biaya yang banyak. LinguSQL adalah sebuah tool pengembangan eksperimen yang mengintegrasikan proses pengujian secara whitebox dan blackbox ke dalam aktifitas pembuatan kodenya. Paper ini memaparkan penerapan LinguSQL dalam pengembangan studi kasus sebuah aplikasi transaksi perdagangan saham. Penerapan LinguSQL pada studi kasus yang cukup kompleks diharapkan akan menampilkan keuntungan konsep pengujian secara menyeluruh serta, dalam konteks implementasi tool, menunjukkan bagian-bagian yang masih perlu dikembangkan lebih lanjut. The ideal process software development always requires thorough testing to obtain the software that has a certain degree of truth. However, in practice very rarely thorough testing done because it requires so much resources of time and cost. LinguSQL is an experimental tool that integrates the development process is whitebox and blackbox testing in manufacturing activity code. This paper describes the implementastion of LinguSQL in the development of a stock trading application case study. Implementation of LinguSQL on a complex case study will show the expected benefit of testing the concept a thorough and in the context of the implementation tool, showing the parts that still need to be developed further

Predicting the response of a submillimeter bolometer to cosmic rays

Bolometers designed to detect. submillimeter radiation also respond to cosmic, gamma, and x rays. Because detectors cannot be fully shielded from such energy sources, it is necessary to understand the effect of a photon or cosmic-ray particle being absorbed. The resulting signal (known as a glitch) can then be removed from raw data. We present measurements using an Americium-241 gamma radiation source to irradiate a prototype bolometer for the High Frequency Instrument in the Planck Surveyor satellite. Our measurements showed no variation in response depending on where the radiation was absorbed, demonstrating that the bolometer absorber and thermistor thermalize quickly. The bolometer has previously been fully characterized both electrically and optically. We find that using optically measured time constants underestimates the time taken for the detector to recover from a radiation absorption event. However, a full thermal model for the bolometer, with parameters taken from electrical and optical measurements, provides accurate time constants. Slight deviations from the model were seen at high energies; these can be accounted for by use of an extended model

Implications of a High Angular Resolution Image of the Sunyaev-Zel'dovich Effect in RXJ1347-1145

The most X-ray luminous cluster known, RXJ1347-1145 (z=0.45), has been the object of extensive study across the electromagnetic spectrum. We have imaged the Sunyaev-Zel'dovich Effect (SZE) at 90 GHz (3.3 mm) in RXJ1347-1145 at 10" resolution with the 64-pixel MUSTANG bolometer array on the Green Bank Telescope (GBT), confirming a previously reported strong, localized enhancement of the SZE 20" to the South-East of the center of X-ray emission. This enhancement of the SZE has been interpreted as shock-heated (> 20 keV) gas caused by an ongoing major (low mass-ratio) merger event. Our data support this interpretation. We also detect a pronounced asymmetry in the projected cluster pressure profile, with the pressure just east of the cluster core ~1.6 times higher than just to the west. This is the highest resolution image of the SZE made to date.Comment: 9 pages, 7 figures; accepted for publication in The Astrophysical Journa

Observations of M87 and Hydra A at 90 GHz

This paper presents new observations of the AGNs M87 and Hydra A at 90 GHz made with the MUSTANG bolometer array on the Green Bank Telescope at 8.5" resolution. A spectral analysis is performed combining this new data and archival VLA data on these objects at longer wavelengths. This analysis can detect variations in spectral index and curvature expected from energy losses in the radiating particles. M87 shows only weak evidence for steepening of the spectrum along the jet suggesting either re-acceleration of the relativistic particles in the jet or insufficient losses to affect the spectrum at 90 GHz. The jets in Hydra A show strong steepening as they move from the nucleus suggesting unbalanced losses of the higher energy relativistic particles. The difference between these two sources may be accounted for by the different lengths over which the jets are observable, 2 kpc for M87 and 45 kpc for Hydra A.Comment: 11 pages, submitted to Ap