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All Journal Jurnal Energi Dan Manufaktur Microbiology Indonesia Makara Journal of Science
Rosari Saleh
FMIPA, Universitas Indonesia
Biochemistry, Genetics & Molecular Biology Energy Immunology & microbiology Industrial & Manufacturing Engineering Medicine & Pharmacology

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Karakterisasi Konduktivitas Termal Nanofluida Oksida Berbasis Fluida Dasar H2O Wayan Nata Septiadi; Nandy Putra; Rosari Saleh
Jurnal Energi Dan Manufaktur Vol 8 No 2 (2015): Oktober 2015
Publisher : Department of Mechanical Engineering, University of Udayana

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Abstrak:Sejak nanofluida mulai diperkenalkan untuk peningkatan konduktivitas termal, hal ini memberikan suatu harapan yang besar bagi bidang perpindahan kalor. Penelitian dan pengaplikasian nanofluida terus mengalami perkembangan dan peningkatan. Pendispersian partikel nano ke dalam fluida dasar sehingga membentuk suatu suspense nanofluida tentunya memiliki karakteristik konduktivitas termal yang berbeda beda antara penggunaan nano partikel satu dengan nano partikel lainnya. Penggunaan nano partikel oksida juga mulai banyak digunakan sebagai fluida kerja alternative baik sebagai fluida kerja alat penukar kalor maupun sebagai fluida kerja pada pipa kalor dan teknologi pendingin lainnya. Hal ini menjadi sangat penting untuk mengetahui karakteristik konduktivitas termal nanofluida oksida pada fraksi volume rendah dan fraksi volume tinggi. Penelitian dilakukan dengan mendispersikan partikel nano CuO, Al2O3 dan TiO2 yang masing masing berukuran 20 nm ke dalam fluida dasar air (H2O) dan dilakukan sonifikasi menggunakan ultrasonic prosessor selama 30 menit. Fraksi volume dibuat dalam fraksi volume rendah yakni 0.1% sampai dengan 0.9% dan fraksi volume tinggi 1% sampai dengan 10%. Pengujian konduktivitas termal nanofluida oksida pada fraksi volume rendah dan fraksi volume tinggi dilakukan dengan menggunakan metode KD2 yang diukur pada temperatur 25oC. Hasil pengujian menunjukkan karakterisasi konduktivitas termal nanofluida oksida yang dalam hal ini adalah CuO-Air, Al2O3-Air dan TiO2-Air masing-masing memberikan peningkatan konduktivitas termal yang signifikan pda fraksi volume rendah. Konduktivitas termal CuO-Air baik pada fraksi volume rendah maupun pada fraksi volume tinggi lebih tinggi dibandingkan dengan konduktivitas termal Al2O3-Air dan TiO2-Air. Kata kunci: Konduktivitas termal, nanofluida, oksida, fraksi volume.Abstract:Since nanofluids was introduced to increase the thermal conductivity, it gives great hope for the field of heat transfer. Research and application of nanofluids continues to experience growth and improvement. Dispersing nanoparticles into the base fluid to form a suspense nanofluids certainly has the different characteristics of a thermal conductivity. The use of nano-oxide particles are also widely used as a good alternative working fluid as the working fluid heat exchanger as well as the working fluid in the heat pipes and other cooling technologies. Its very important to know the characteristics of the thermal conductivity of nanofluids oxide at low and high volume fraction. The study was conducted by dispersing nanoscale particles of CuO, Al2O3 and TiO2 are each measuring 20 nm in a base fluid water (H2O) and doing sonification using ultrasonic processor for 30 minutes. Fraction volume created in volume fraction lower at 0.1% to 0.9% and a high volume fraction of 1% to 10%. Thermal conductivity of nanofluids testing oxides at low volume fraction and a high volume fraction KD2 done using a method that is measured at a temperature of 25oC. The test results show the characterization of thermal conductivity of nanofluids oxide in this case is CuO- Water, Al2O3-Water and TiO2-Water each provide a significant increase in thermal conductivity at low volume fraction. The thermal conductivity of CuO-water nanofluid higher at low and high volume fraction than the thermal conductivity of Al2O3-Water and TiO2-Water. Keywords: Thermal conductivity, nanofluids, oxide, volume fraction.
Effect of Backbone, Sequence, and Positional Disorders on Electrical Transport in Modified Poly(dA)–Poly(dT) DNA Wire Suhendro, Daniel Kurnia; Yudiarsah, Efta; Saleh, Rosari
Makara Journal of Science Vol. 23, No. 1
Publisher : UI Scholars Hub

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The effect of medium and thermal fluctuations on charge transport in two types of modified poly(dA)–poly(dT) DNA was studied by calculating the transmission probability and current–voltage (I–V) characteristics of a model DNA wire sandwiched between two metal electrodes. Modification was performed by randomly replacing several A–T base pairs with C–G or G–C base pairs along the DNA chain. The medium–DNA interaction was modeled as the backbone onsite energy disorder in the DNA tight-binding Hamiltonian. The helicity of the molecule was considered by incorporating twist-angle-dependent intrastrand hopping amplitude in the model. Thermal fluctuation was modeled by varying the twist angles of each base in the DNA wire. Twist-angle disorder was influenced by temperature and frequency. The I–V results obtained by modeling the backbone disorder effect showed that the current decreased and the threshold voltage generally increased as disorder strength increased to a critical value. The current increased and the threshold voltage decreased as the disorder strength exceeded this critical value. However, certain values of the backbone disorder reduced the threshold voltage before the critical value was reached because the transmission bands shifted toward the Fermi energy. The results of thermal fluctuation modeling indicated that increasing thermal fluctuation (increasing temperature and decreasing frequency) degraded the electrical properties of the DNA modified with C–G base pairs but enhanced those of the DNA modified by G–C base pairs. This trend, however, did not always hold for all frequency values for the latter DNA type.
Characterization of Thermoplasma Species Cultured from Sampling on Tangkuban Perahu, Indonesia AMARILA MALIK; IMAN SANTOSO; ANDI YEHUDA; SERUNI K.U. FREISLEBEN; SEPTELIA INAWATI WANANDI; HARALD HUBER; ZESSINDA LUTHFA; ROSARI SALEH; HANS-JOACHIM FREISLEBEN
Microbiology Indonesia Vol. 8 No. 1 (2014): March 2014
Publisher : Indonesian Society for microbiology

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (143.895 KB) | DOI: 10.5454/mi.8.1.3

Abstract

Archaea is an organisme with unique feature because of its ability to inhabit an extremophyle conditions. Our expeditions to Tangkuban Perahu, West Java aimed to obtain archaealstrains from the solfatara fields located in Domas crater. From the samples, we intended to culture Thermoplasma species growing around 55 °C below pH 2, which until now have not yet been fully characterized. We collected five samples from mud holes with temperatures from 52 °C to 57 °C and pH below 2. In serial cultures of up to 8 transfers in Freundt’s medium we grew tetraetherlipid synthesizing Thermoplasma species as documented by phase contrast microscope. Total membrane lipid extracts were analysed by thin layer chromatography; the pattern matched total lipid extracts from Thermoplasma acidophilum DSM 1728 membranes. For confirmation, 16S rDNA identification performing PCR and sequencing were carried-out. Analysis using BLAST showed T. acidophilum identities as the highest similarity of 99%, followed by T. volcanium, also with99% similarity (ANKF776908 and ANKF776909). This is the first report of culturing cell-wall-less thermoacidophilicarchaea,in particular Thermoplasma species in Indonesian laboratories.
STUDI KARAKTERISASI OPTIS LAPISAN TIPIS a-SiC:H HASIL DEPOSISI METODE GLOWDISCHARGE Saleh, Rosari; Munisa, Lusitra; Marianty, Dewi
Makara Journal of Science Vol. 7, No. 3
Publisher : UI Scholars Hub

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Optical Properties of a-SiC:H Films Deposited by Glowdischarge Methods. The optical properties of amorphous silicon carbon films deposited by glowdischarge method have been studied using ultra violet-visible (uv-vis) spectroscopy. The refractive index was calculated by Swanepoel’s formula using transmission data then followed by numerical simulation. The films density tends to decrease with increasing carbon content. The widening of the optical gap by increasing carbon content indicates the enhancement of film’s transparence. Both real and imaginary parts of the dielectric constant show variation in magnitude as the carbon content increase
PENGARUH ANIL TERMAL TERHADAP BESARAN OPTIS LAPISAN TIPIS a-SiC:H HASIL METODE DC SPUTTERING II. TARGET GRAFIT Saleh, Rosari; Munisa, Lusitra; Marianty, Dewi
Makara Journal of Science Vol. 7, No. 1
Publisher : UI Scholars Hub

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The Effect of Thermal Annealing on the Optical Properties of a-SiC:H Films Produced by DC Sputtering Methods: I. Graphite Target Case. A study of the annealing effect on optical properties and disorder of hydrogenated amorphous silicon carbon (a-SiC:H) films was undertaken. The films were prepared by sputtering technique using graphite target and silicon wafer in argon and hydrogen gas mixture, and then characterized by uv-vis (ultra violet-visible) spectroscopy before and after annealing. Index of refraction n and absorption coefficient α of films have been determined from measurements of transmittance. The optical gap show small variation with annealing temperature, increasing with increasing annealing temperature up to 500 °C. An increase of annealing temperature leads to reduced film density and the amorphous network disorder. The experimental results are discussed in terms of deposition condition and compared to other experimental results.
PENGARUH ANIL TERMAL TERHADAP BESARAN OPTIS LAPISAN TIPIS a-SiC:H HASIL METODE DC SPUTTERING I. TARGET SILIKON Saleh, Rosari; Munisa, Lusitra; Marianty, Dewi
Makara Journal of Science Vol. 7, No. 1
Publisher : UI Scholars Hub

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The Effect of Thermal Annealing on the Optical Properties of a-SiC:H Films Produced by DC Sputtering Methods: I. Silicon Target Case. The effects of thermal annealing treatment on the optical properties of amorphous silicon carbon films deposited by silicon target in an argon, methane and hydrogen gas mixture have been studied using ultra violet-visible (uv-vis) spectroscopy. Both n and α, and consequently the real and imaginary parts of the dielectric constant, show a considerable variation with subsequent annealing up to annealing temperature 500 °C, with the most rapid changes occurring for temperature 300 °C. The films tend denser as the annealing temperature increased up to 500 °C. The optical gap improved slightly upon annealing, where as the disorder of the amorphous network reduced. The annealing treatment produces reorganization of the amorphous network since thermal annealing results in dissociation of hydrogenated bonds (Si-H and C-H).
PENGARUH PENINGKATAN FLOW RATE GAS METAN TERHADAP SIFAT OPTIS LAPISAN TIPIS AMORF SILIKON KARBON (a-SiC:H) HASIL DEPOSISI METODE DC SPUTTERING Munisa, Lusitra; Saleh, Rosari
Makara Journal of Science Vol. 6, No. 1
Publisher : UI Scholars Hub

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Methane Flow Rate Effects On The Optical Properties of Amorphous Silicon Carbon (a-SiC:H) Films Deposited By DC Sputtering Methods. We have investigated the refractive index (n) and the optical absorption coeffi cient (α) from refl ection and transmission measurements on hydrogenated amorphous silicon carbon (a-SiC:H) fi lms. The a-SiC:H fi lms were prepared by dc sputtering method using silicon target in argon and methane gas mixtures. The refractive index (n) decreases as the methane fl ow rate increase. The optical absorption coeffi cient (α) shifts to higher energy with increasing methane fl ow rate. At higher methane fl ow rate, the fi lms tend to be more disorder and have wider optical gap. The relation of the optical properties and the disorder amorphous network with the compositional properties will be discussed.
PENENTUAN KONSTANTA OPTIS DI DAERAH ABSORPSI FUNDAMENTAL MENGGUNAKAN FORMULASI FOROUHI DAN BLOOMER UNTUK LAPISAN TIPIS AMORF SILIKON KARBON (a-SiC:H) Saleh, Rosari; Munisa, Lusitra; Marianty, Dewi
Makara Journal of Science Vol. 6, No. 2
Publisher : UI Scholars Hub

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An expression of the imaginary and real parts of the complex refractive index derived by Forouhi and Bloomer have been applied to obtain wider energy range of optical constants for amorphous silicon carbon (a-SiC:H) films deposited by dc sputtering method using silicon and graphite targets. Excellent agreement was obtained between the formula and experimentally measured values of both n(E) and k(E). The optical constants obey Kramers-Kronig dispersion relation and show a maximum at high-energy range. The dependence of five parameters to carbon concentration and the variation of optical constants with composition for both targets will be discussed.
STUDI DISORDER LAPISAN TIPIS AMORF SILIKON KARBON (a-SiC:H) HASIL DEPOSISI METODE DC SPUTTERING Munisa, Lusitra; Saleh, Rosari
Makara Journal of Science Vol. 6, No. 2
Publisher : UI Scholars Hub

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Disorder Study of Amorphous Silicon Carbon (a-SiC:H) Films Deposited by DC Sputtering Method. Disorder amorphous network of amorphous silicon carbon (a-SiC:H) films has been investigated for films prepared by dc sputtering method. The films were deposited using silicon target in argon and methane gas mixtures. The optical absorption coefficients have been performed by UV-VIS (ultra violet-visible) reflectance and transmittance spectroscopy. Disorder parameter has been obtained from the optical absorption coefficient α (E) using Tauc plot. Increasing methane flow rate has an effect on increasing Tauc gap and decreasing disorder parameter. The amorphous network of the films tends to be more disorder with increasing methane flow rate. The relation of disorder amorphous network with structural and compositional properties will be discussed.
Co-Authors Amarila Malik ANDI YEHUDA Daniel Kurnia Suhendro Dewi Marianty Efta Yudiarsah, Efta HANS-JOACHIM FREISLEBEN HARALD HUBER IMAN SANTOSO Lusitra Munisa Marianty, Dewi Munisa, Lusitra Nandy Putra SEPTELIA INAWATI WANANDI SERUNI K.U. FREISLEBEN Suhendro, Daniel Kurnia Wayan Nata Septiadi ZESSINDA LUTHFA