Sintesis Fasa ɣ-Co Pada Paduan Co26cr6mo0.18n Dengan Kombinasi Metode Homogenisasi 1200 Oc Dan Hot Rolling Serta Transformasi Struktur Kristalnya

Paduan Co-Cr-Mo merupakan material yang banyak digunakan sebagai bioimplan di bidang medis karena ketahanan korosi dan sifat mekaniknya. Secara struktur, paduan Co-Cr-Mo yang direkomendasikan untuk aplikasi medis berupa fasa ɣ-Co yang berstruktur FCC. Dalam pembuatannya seringkali fasa metastabil Co7Mo6 muncul. Munculnya fasa Co7Mo6 ini akan menurunkan komposisi dari fasa ɣ-Co. Studi ini bertujuan untuk mensintesis fasa ɣ-Co tanpa diikuti munculnya fasa Co7Mo6 menggunakan kombinasi homogenisasi 1200 oC dan hot rolling yang dilanjutkan dengan pendinginan. Paduan yang digunakan adalah ingot Co26Cr6Mo0.18N. Pendinginan dilakukan dengan tiga variasi yaitu menggunakan air dingin, air dan udara. Transformasi struktur kristal dari kubik primitif menjadi FCC terjadi saat pendinginan menggunakan air dan udara yang berarti fasa ɣ-Co berhasil terbentuk dengan pendinginan menggunakan air dan udara. Namun, pada hasil pendinginan dengan air, fasa Co7Mo6 masih terbentuk, sedangkan pada hasil pendinginan dengan udara tidak terbentuk lagi. Secara struktur, hasil pendinginan dengan udara menghasilkan fasa ɣ-Co yang paling stabil dibandingkan dengan pendinginan air dan air dingin. Kekurangan yang ada setelah pendinginan dengan udara adalah munculnya fasa ɛ-Co yang bersifat getas yang merupakan dislokasi parsial akibat proses hot rolling

Analisis Miskonsepsi Siswa Kelas XI SMA Pada Materi Larutan Penyangga Menggunakan Instrumen Tes Three Tier Multiple Choice

The research is aimed to analyze misconceptions of high school students of class XI on the buffer solution material using instruments Three Tier Multiple Choice Tests. Another purpose of this study was to determine the percentage of student misconceptions and location misconceptions on chemical material especially on the subject of buffer solution. The research method is descriptive, data collection by giving a 13 item multiple choice questions with closed reason and CRI index and then the results of each items students answer were analyzed. The results of this study are misconceptions in chemistry learning especially in a buffer solution dispersed in of all concepts. The most common misconceptions on the working principle of the buffer solution by 51% and the lowest on the properties of the buffer solution by 31%. Suggestions put forward is the need to hold further research to uncover misconceptions where they come from and how to overcome these misconceptions

Ekstraksi Emas Dari Limbah Papan Sirkuit Telepon Genggam Menggunakan Teknik Membran Cair Emulsi

Penelitian ini bertujuan untuk menentukan persen ekstraksi emas dari limbah papan sirkuit telepon genggam dengan teknik membran cair emulsi menggunakan MIBK sebagai carrier. Reaksinya terjadi secara simultan di permukaan membran, antara senyawa yang akan dipisahkan pada fasa umpan dengan senyawa pembawa pada fasa organik. Logam emas hasil reaksi akan terdifusi ke fasa membran yang pada akhirnya hasil ekstraksi terkumpul dan terkonsentrasi di fasa penerima. Sebelum diaplikasikan ke limbah telepon , terlebih dahulu dipelajari beberapa parameter yang berpengaruh terhadap perolehan persen ekstraksi. Pada penelitian ini kondisi optimum untuk parameter pembuatan fasa emulsi yaitu 1:1, pengaruh kecepatan pembuatan emulsi pada yaitu 1000 rpm.Pengaruh konsentrasi carrier terhadap persen ekstraksi emas dengan konsentrasi MIBK sebesar 3%, pengaruh kecepatan kontak terhadap persen ekstraksi emas adalah pada 1000 rpm. Penerapan kondisi optimum pada limbah papan sirkuit telepon genggam memberikan persen ekstraksi Au sebesar 83.24%. Kata Kunci: limbah papan sirkuit telepon genggam, MIBK, teknik membran cair emulsi. Abstrack This research aim is to determine extraction percentage of gold from cellular phone circuit board waste using emulsion liquid membrane technique with Methyl Isobutyl Ketone (MIBK) as carrier. The reaction occur simultaneously on the membrane surface, between compound going to be separate in feed phase with carrier compound in organic phase. Gold from reaction will diffuse into membrane phase which finally will be collected and concentrated in receiving phase. Before it applied to phone waste, there are several parameters studied which influence the extraction percentage result. In this research the optimum condition for building emulsion phase parameter is 1:1, effect on building emulsion rate is 1000 rpm. Carrier concentration effect to extraction percentage of gold is at 3% MIBK and contact rate effect is at 1000 rpm. Optimum condition application to cellular phone circuit board waste give Au extraction percentage of 83.24%

SINTESIS FASA ɣ-Co PADA PADUAN Co26Cr6Mo0.18N DENGAN KOMBINASI METODE HOMOGENISASI 1200 oC DAN HOT ROLLING SERTA TRANSFORMASI STRUKTUR KRISTALNYA

Co-Cr-Mo alloy is a material that widely used for bioimplant in the medical field due to its corrosion resistance and mechanical properties. Structurally, recommended Co-Cr-Mo alloys for medical applications are ɣ-Co phase which has an FCC structure. But, Co7Mo6 metastable phase often occurs after its synthesis. The formation of Co7Mo6 phase will decrease the composition of ɣ-Co phase. This study aimed to synthesize ɣ-Co phase without following the appearance of Co7Mo6 phase using a combination of 1200 oC homogenization and hot rolling followed by cooling treatment. The alloy used was Co26Cr6Mo0.18N ingot. Cooling treatments were done using the variation of cold water, water and air. The transformation of the crystal structure from the primitive cubic to the FCC occurs during water and air cooling treatments which means that ɣ-Co phase is successfully formed by those cooling treatments. However, Co7Mo6 phase is still formed on the water cooling treatment while none of  Co7Mo6occurred on the air cooling treatment. Structurally, air cooling treatment produces most stable ɣ-Co phase than the others. However, brittle ɛ-Co phase as a partial dislocation is formed after air cooling treatment due to imperfection of hot rolling treatment

Primer concentration and Pre-denaturation Time Effect on cyt-K Bacillus cereus Detection using Real-Time PCR Method

Foodborne disease is a global threat that can affect all sections of society, both in developed or developing countries. Bacillus cereus is a Gram-positive bacteria that can cause food poisoning disease in humans. [2] Real-Time PCR detection method is one of the molecular marker methods that has been widely recognized as a fast, reliable, sensitive and specific detection tool for detecting pathogenic bacteria. In previous studies, the optimum condition and formulas applied for cyt-K 2 primer pairs have been obtained using Real-Time PCR. The purpose of this study is to find out the best conditions work of the primer pair cyt-K Bacillus cereus on detecting bacteria target using variations of pre-denaturation time and primer concentration with Real-Time PCR method. The annealing temperature used for PCR is at 60°C with sample concentration 50 ng/µL of B. cereus. Real-time PCR detection of variations in pre-denaturation time and primer concentration obtained the best conditions for primer pair cyt-K work at minute 4 with a primer concentration of 10 pmol and successfully amplifying the target by producing a Ct value of B. cereus at 13.04. Based on the results of the study, the primer pair cyt-K were reproducible in detecting the target gene and in the further step, this research can be continued to developed a prototype detection kit for foodborne pathogen bacteria using Real-Time PCR method