Pembentukan Kokristalantarakalsium Atorvastatin dengan Isonikotinamid dan Karakterisasinya

PEMBENTUKAN KOKRISTALANTARAKALSIUM ATORVASTATIN DENGAN ISONIKOTINAMID DAN KARAKTERISASINYA. Penelitian ini bertujuan untuk meningkatkan kelarutan dan laju pelarutan atorvastatin dengan menggunakan metode kokristalisasi. Proses kokristalisasi dilakukan dengan metode solvent evaporation, solvent-drop grinding pada atorvastatin dan koformer (isonikotinamid) masing-masing dengan perbandingan 1:1 (satu mol atorvastatin dengan satu mol isonikotinamid digerus selama 15 menit sambil ditambahkan beberapa tetes metanol. Penambahan methanol berfungsi untuk mempercepat pembentukan kokristal. Kokristal dikarakterisasi menggunakan difraktometer sinar-x,mikroskop polarisasi, Scanning Electron Microscope (SEM), spektrometer infra merah dan Differential Scanning Calorimeter (DSC). Difraktogram dari kokristal menunjukkan intensitas puncak yang lebih rendah dibandingkan atorvastatin standar yang menunjukan telah terbentuk habit kristal baru. Hasil spektrometer infra merah, menunjukkan tidak adanya interaksi kimiawi dan Perubahan struktur saat dimodifikasi menjadi kokristal. Thermogram DSC menunjukkan adanya Perubahan titik leleh berbeda yang menandai adanya bentuk kristalin baru. Demikian juga pengamatan di bawah mikroskop polarisasi dan SEM menunjukkan bentuk kristal yang relatif baru dibandingkan dengan atorvastatin murninya. Hasil uji kelarutan dan laju pelarutan kokristal atorvastatin-isonikotinamida menunjukkan peningkatan dibandingkan dengan kelarutan dan laju pelarutan atorvastatin sendiri

Well log interpretation of certain geothermal fields in the Imperial Valley, California

This study reviews the wireline log responses of some geothermal fields in the Imperial Valley, California. The fields under study include the Heber, the East Mesa, the Brawley, and the Westmoreland. The well logs used in the study did not include all the wireline surveys obtained by the operators. The selected well logs obtained under special arrangements with the operators were chosen to maintain the anonymity of specific well locations but are only representative of each area. Analysis of the well logs indicates that on an individual field basis, the well logs are excellent for correlation purposes. The presence of extremely saline fluids in some fields precludes the monitoring of Q/sub v/ (cation exchange capacity per unit volume) profile for detection of hydrothermally altered zones. The producing sections in all the fields are characterized by low porosity and high resistivity

Lithology and hydrothermal alteration determination from well logs for the Cerro Prieto Wells, Mexico

The purpose of this study is to examine the characteristics of geophysical well logs against the sand-shale series of the sedimentary column of the Cerro Prieto Geothermal Field, Mexico. The study shows that the changes in mineralogy of the rocks because of hydrothermal alteration are not easily detectable on the existing logs. However, if the behavior of clay minerals alone is monitored, the onset of the hydrothermally altered zones may be estimated from the well logs. The effective concentration of clay-exchange cations, Q/sub v/, is computed using the data available from conventional well logs. Zones indicating the disappearance of low-temperature clays are considered hydrothermally altered formations with moderate to high-permeability and temperature, and suitable for completion purposes