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Abstrak :
[ABSTRAK
Multifungsi untuk terapi kanker tulang dan regenerasi jaringan tulang mulai dipelajari dengan menggunakan scaffold komposit biopolimer dan magnetik. Penelitian ini bertujuan menyintesis dan mengarakterisasi scaffold karbonat apatit/kitosan/alginat/partikel magnetik kalsium alumina ferrit serta menganalisis viabilitas selnya. Pertama disintesis karbonat apatit kemudian dicampurkan dengan kitosan, alginat dan kalsium alumina ferrit kemudian di freeze drying untuk mendapatkan scaffold. Hasil menunjukkan terbentuknya struktur komposit. Kalsium alumina ferrit berbentuk irregular dan berukuran 0,5-2 μm. Magnetisasi partikel kalsium alumina ferrit dan scaffold magnetik ditunjukkan dengan magnetisasi saturasi, medan koersivitas dan magnetisasi remanen. Scaffold tersebut teramati tidak mempengaruhi viabilitas sel HaCaT.

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ABSTRACT
Multifunction for bone cancer therapy and bone tissue regeneration has been studied using biopolymers and magnetic composite scaffolds. The aim of stud was to synthesize and characterize the carbonate apatite/chitosan/alginate/calcium aluminate ferrite composite scaffold as well as to analyze the cell viability. Firstly, carbonate apatite was synthesized and then was mixed with chitosan, alginate and calcium aluminate ferrite. Then the resulted gel was freeze dried to obtain the scaffold. Results indicated the formation of a composite structure. Calcium aluminate ferrite particle were irregular in shape and 0.5-2 μm in size. Magnetizations of the calcium aluminate ferrite particle and the magnetic scaffolds were demonstrated in the saturation magnetization, coercivity field and remanent magnetization. The produced scaffold was observed did not affect the viability of HaCaT cells., Multifunction for bone cancer therapy and bone tissue regeneration has been studied using biopolymers and magnetic composite scaffolds. The aim of stud was to synthesize and characterize the carbonate apatite/chitosan/alginate/calcium aluminate ferrite composite scaffold as well as to analyze the cell viability. Firstly, carbonate apatite was synthesized and then was mixed with chitosan, alginate and calcium aluminate ferrite. Then the resulted gel was freeze dried to obtain the scaffold. Results indicated the formation of a composite structure. Calcium aluminate ferrite particle were irregular in shape and 0.5-2 μm in size. Magnetizations of the calcium aluminate ferrite particle and the magnetic scaffolds were demonstrated in the saturation magnetization, coercivity field and remanent magnetization. The produced scaffold was observed did not affect the viability of HaCaT cells.]

Abstrak :
ABSTRAK
Deposit logam las SMAW 308L dengan variasi ferrit, nitrogen dan fluk basicity dievaluasi untuk meneliti pengaruhnya terhadap kekuatan mekanik dan perilaku korosi. Sifat mekanik diteliti melalui kekuatan tarik pada suhu kamar, charpy impak V-notch dan lateral expansion (LA) di suhu kriogenik -196oC. Polarisasi siklik potensiodinamik dilakukan pada lingkungan NaCl 3.5%w.t untuk mengamati potensial pitting dan hysteresis loop. Peningkatan ferrit dari 2-10FN, secara umum meningkatkan kekuatan logam lasan sebesar 0.5-4.9%. Pengurangan ferrit dari 4FN menjadi 2FN, meningkatkan secara signifikan charpy impak sebesar 21% dan LA sebesar 69%. Lasan dengan kandungan nitrogen yang lebih rendah memiliki charpy impak 10% lebih tinggi dan LA 37% lebih tinggi. Fluk tipe basa memiliki charpy impak 16% lebih besar dan LA 51% lebih besar. Positif hysteresis loop menunjukkan bahwa logam 308L rawan terhadap korosi pitting pada lingkungan NaCl 3,5%wt. Keberadaan ferrit mengurangi ketahanan terhadap korosi sumuran yang ditandai oleh penurunan nilai Epit. Nitrogen yang lebih rendah mengakibatkan Epit menjadi lebih aktif sementara itu Fluk tipe basa memiliki Epit yang lebih noble. Ketangguhan kriogenik dan ketahanan korosi pada logam las 308L dikontrol oleh kandungan ferrit yang rendah, kandungan nitrogen yang rendah dan fluk yang lebih basa. Sementara itu kekuatan mekanik dikontrol oleh kandungan ferrit yang tinggi

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ABSTRACT
SMA (Shielded Metal Arc) welds metal 308L with variation in ferrite, nitrogen and flux basicity were evaluated in order to study its influence to mechanical and corrosion behavior. Mechanical behaviors were investigated by using tensile strength at room temperature, charpy impact V-notch and lateral expansion(LA) at cryogenic temperature -196oC. Cyclic polarization potensiodynamic was performed at 3.5% NaCl to observe pitting potential and hysteresis loop. Increment ferrite from 2-10 FN, in general increased 0.5- 4.9% welds strength. Reduction from 4FN to 2 FN had significantly increased charpy impact and LA to 21% and 69% respectively. Weld with lower nitrogen content had 10% higher charpy impact and 37% higher LA. Basic flux significantly increased charpy impact to 16% and LA to 51%. Positive hysteresis loop showed that 308L welds were prone to pitting corrosion at 3.5%w.t chloride solution. Present of ferrite reduced pitting corrosion resistance which indicated by Epit reduction. Lower nitrogen showed more active Epit. Weld with higher flux basicity resulted noble Epit. Cryogenic toughness and corrosion resistance at SMA 308L weld metal are controlled by low ferrite content, low nitrogen content and more basic flux. Meanwhile weld metal strength are controlled by high ferrite content.

Abstrak :
Pengelasan sebagai salah satu metode fabrikasi pada industri minyak dan gas tidak selalu menghasilkan kualitas hasil lasan yang baik. Adanya cacat pada hasil lasan menyebabkan hasil lasan reject sehingga material perlu untuk diperbaharui. Alternatif lain yang dapat dilakukan adalah melakukan perbaikan pengelasan dengan cara mengekskavasi hasil lasan yang terdapat cacat. Akan tetapi proses ini berpengaruh terhadap sifat mekanik dan struktur mikro akibat adanya masukan panas. Dengan API 5L Grade B sebagai material uji, penelitian menggunakan metode pengelasan manual (SMAW) dan dilakukan pengujian pada tiga sampel pipa hasil lasan yaitu sebelum pengelasan (BR), repair 1 (R1), dan repair 2 (R2), dan dibandingkan sifat mekanik dan struktur mikronya. Hasil pengujian struktur mikro pada menunjukan terjadinya perbesaran ukuran butir dengan bertambahnya proses perbaikan. Terbentuknya fasa acicular ferrite pada weld metal dan HAZ meningkatkan sifat mekanik pada sampel R1. Berdasarkan hasil pengujian tarik didapatkan bahwa proses perbaikan sebanyak dua kali masih memenuhi standar pengujian tarik, dengan nilai kekuatan tarik maksimum tertinggi dihasilkan oleh R1 sebesar 531 MPa dan mengalami penurunan pada R2 menjadi 518 MPa. Hasil pengujian kekerasan menunjukan bahwa semakin banyak proses perbaikan maka nilai kekerasan akan semakin menurun akibat masukan panas yang semakin tinggi, tetapi distribusi kekerasan lebih merata. Perbaikan pengelasan menyebabkan terjadi penurunan ketangguhan pada R2 akibat menurunnya kadar acicular ferrite dan perbesaran butir. ......Welding, one of the fabrication methods in the oil and gas industry, does not always produce good quality welds. The existence of defects causes the weld to get rejected, and the need for material renewal. Welding repair, which is to excavate the welds containing defects, can be done as alternative. However, existence of heat input used in welding repair process may alter the mechanical properties and microstructure of the material. Using API 5L Grade B as base material, research which used the SMAW welding method, and testing was done on three samples of welded pipes, named before repair (BR), repair 1 (R1), and repair 2 (R2), and compared their mechanical properties and microstructure. The microstructure tests showed an increase in the grain size along with an increase in the number of repairs. The formation of the acicular ferrite phase on the weld metal and HAZ increased the mechanical properties of the R1 sample. The tensile test results showed that the double repair process still meet the tensile test standards, with the highest tensile strength value was made by R1 of 531 MPa and decreasing at R2 to 518 MPa. The hardness tests show that increasing the number of repair processes decreases hardness properties due to the higher heat input, but with more even hardness distribution. All in all, welding repair causes a decrease in the toughness of the weld metal due to a decrease in acicular ferrite content and grain growth.