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Abstrak :
ABSTRACT
One of the attempts performed to improve advanced materials is the application of superconducting wires as base materials for medical application. Magnesium Diboride MgB2 is one of the most promising superconducting wires that can be used to replace superconducting wires Nb. MgB2 superconductor has relatively high critical temperature, however, the main problem in manufacturing MgB2 superconducting wires is the formation of crack at the surface. This crack formation should be avoided, because crack will weaken the superconductivity of a material. There are several ways to avoid the formation of crack, which include the usage of Fe tube. The critical temperature of pure MgB2 is higher than Nb group superconductor, and this critical temperature of MgB2 still can be enhanced by several methods such like doping. Recently, it was found that doping of SiC can make the critical temperature of MgB2 superconductor enhanced. In this research, Powder in Tube PIT were used. These powders were then poured into the Fe tubes with heat treatment under an argon environment. These samples were then characterized by using X Ray Diffraction XRD , Scanning Electron Microscopy SEM and resistivity testing under TC. The results show that nano SiC can be a very high potential doping agent for MgB2 superconducting wires, however, further sample preparation should be considered in manufacturing MgB2 wires. This is true since the unexpected phases such like MgO and Mg2Si exist in the phase. Applying heat treatment to MgB2 can causes instability in MgB2, and thus having all sample prepared under vacuum is recommended. There is also a chance for the boron inside the MgB2 can also doped inside the SiC, especially for nano SiC which have high surface area. Hence, liquid phase sintering would likely to be recommended, due to dissolving of boron into molten magnesium.

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ABSTRACT
Salah satu upaya yang dapat dilakukan untuk mengembangan material maju adalah penggunaan kawat superkonduktor sebagai material dasar untuk banyak aplikasi di dunia kedokteran. Magnesium diborida MgB2 adalah salah satu kawat superkonduktor yang memiliki potensi besar untuk dipakai sebagai pengganti kawat superkonduktor tipe Nb. Superkonduktor MgB2 memiliki temperatur kritis yang relative tinggi high temperature superconductor, HTS . Masalah yang timbul dalam proses pembuatan kawat superkonduktor MgB2 adalah terbentuknya retak pada permukaan. Pembentukan retak permukaan ini harus dicegah karena akanmenggangu nilai superkonduktifitasnya. Beberapa upaya telah dilakukan untuk mencegah terbentuknya retak permukaan, antara lain penggunaan Fe tube. Meskipun temperatur kritis dari MgB2 sudah lebih tinggi dari superkonduktor tipe Nb, namun ternyata temperatur kritis dari MgB2 masih dapat ditingkatkan, diantara lain menggunakan dopan. Dalam penelitian ini, dopan nano-SiC digunakan untuk meningkatkan temperatur kritis dari MgB2. Dalam penelitian ini, metoda in-situ Powder in Tube PIT digunakan untuk membuat kawat superkonduktor. Proses ini dilanjutkan dengan proses perlakuan panas pada lingkungan gas Argon. Setelah kawat superkonduktor dibuat, akan dilakukan analisis karakterisasinya dengan memakai XRD, SEM dan pengukuran resistivity untuk mengetahui sifat superkonduktivitas kawat tersebut. Untuk hasilnya, ditemukan beberapa senyawa yang tidak diinginkan seperti MgO, Mg2Si dan Si whiskers. Ini disebabkan karena berbagai faktor seperti kurangnya panas ataupun keadaan lingkungan tidak vakum.

Abstrak :
Ice slurry terdiri dari campuran air bersuhu rendah dan additiv yang diubah menjadi ice slurry atau cairan es-air dengan pendinginan yang disertai proses pengadukan oleh auger. Sistem ice slury mempunyai potensi mencapai keuntungan secara lingkungan dan ekonomis. Kapasitas pendinginan (cooling capacity) dan ice slury dapat mencapai 4 sampai 6 kali dibanding chilled water, tergantung fraksi esnya. Berbagai refrigerant primer yang tersedia saat ini dapat dipakai untuk memproduksi ice slury. Ice slury dapat dipakai sebagai metoda pendinginan alternatif Kecilnya ukuran partikel menghasilkan area luasan heat transfer yang lebih besar dengan perbandingan berat yang sama dibandingkan jumlah es yang lain. Karakteristik dari formasi kristal Ice Slury memungkinkan pengguna untuk memompa cs, yang memudahkan penggunaan dan kontak penuh dengan produk akan meningkatkan efisiensi pendinginan. Aplikasinya mencakup bidang industri. komersial, kedokteran dan aplikasi khusus lainnya. Tulisan ini menjelaskan tentang proses pemncangan peralatan pemhuat ice slurry yang selanjutnya akan disebut ice slurry generator berdarkan sistem refrigerasi yang menggunakan 2 evaporator yang dihubungkan dengan salah satu evaopator sebgai sarana pembuatan ice slurry dan lainnya sebagai tempat penyimpanannya. Dimesi peralatan dan perlengkapannya dibuat berdasarksn beban pendinginan dan desain temperatur yang ditentukan sebelumnya. Berdasarkan parcobaan dari alat yang dibuat, maka dengan menjalankan peralatan sampai mencapai temperatur rancangan lalu lalu diamati ice slurry yang dihasilkan. Diketahui bahwa kristalisasi es yang dihasilkan mempunyai... ......Slurry ice composed of a low temperature water-additive mixture which transformed into ice slurry by cooling accompanied by continous auger stirring. Ice slurry system has the potential to achieve economical and environmental benefit il's cooling capacity up to 4 to 6 times compared to chilled water, depending on its ice fraction. Various refrigerants available today allowed to be employed to produce ice slurry. Ice slurry can be addressed as alternative cooling method. The relatively small size of Ice slurry resulting in large heat transfer area which is considerably greater with the same weight proportion, compared to other ices. Ice slurry crystal formation characteristic made it possible for pumping operation, which significantly increase its application easiness and the full contact with product will enhance the cooling efficiency. Ice slurry application ranging from industry, commercial to medicine and several other special applications. This paper describe the design process of ice slurry generator based on 2 connected evaporator system with one evaporator as ice slurry production and the other served as collector and storage. Ice slurry generator dimension and its apparatus devised based on the pre determined cooling load and temperature design. Based on experiment conducted on the manufactured device, by operating it to achieved the designed temperature. and Observation on the ice slurry produced, it is reported that the ice crystal produced having coarse texture and will be easily broken by hand crushing, while the other will be suspended as hard grainy texture and harder to be broken. The ice slurry diameter less than I mm. Also, it is found out that in ice slurry collector chamber the ice slurry remain not melting up to 2 hour thanks to system's...

Abstrak :
This report is focused on the linear region of I-V characteristics of nanoscale highly-doped p-i-n diodes fabricated within ultrathin silicon-on-insulator (SOI) structures with an intrinsic layer length of 200 nm and 700 nm under a forward bias at a temperature range from 50 K to 250 K. The doping concentrations of Boron and Phosphorus in SOI p-i-n diodes are high, 1×1020 cm-3 and 2×1020 cm-3, respectively. The linearity of I-V characteristics of the p-i-n diodes under a certain forward bias voltage range and temperature range from 50 K to 250 K indicate these devices are suitable for low temperature sensing purposes. We conclude that highly-doped p-i-n diodes produce a higher current as the temperature decreases under a certain bias voltage range. Nanoscale diodes with longer and wider intrinsic layers generate higher currents under a certain range of bias voltage and low temperature measurements.

Abstrak :
Helium Cryogenics, 2nd edition brings these advances in helium cryogenics together in an updated form. As in the original edition, the author's approach is to survey the field of cryogenics with emphasis on helium fluids. This approach is more specialized and fundamental than that contained in other cryogenics books, which treat the associated range of cryogenic fluids. As a result, the level of treatment is more advanced and assumes a certain knowledge of fundamental engineering and physics principles, including some quantum mechanics. The goal throughout the work is to bridge the gap between the physics and engineering aspects of helium fluids to provide a source for engineers and scientists to enhance their usefulness in low-temperature systems.