Determination of Oxygen Dissolution Rate from Silica to Silicon Melt at Solid (Silica Glass)/Melt/Gas Triple Junction

2002 ◽  
Vol 5 (8) ◽  
pp. G72 ◽  
Author(s):  
Susumu Sakai ◽  
Yasunori Okano ◽  
Xinming Huang ◽  
Keigo Hoshikawa
Keyword(s):  
Dissolution Rate ◽  
Triple Junction ◽  
Silica Glass ◽  
Oxygen Dissolution ◽  
Silicon Melt

scholarly journals EXAFS Determination of Clay Minerals in Martian Meteorite Allan Hills 84001 and Its Implication for the Noachian Aqueous Environment

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 176
Author(s):  
Ryoichi Nakada ◽  
Gaku Tanabe ◽  
Iori Kajitani ◽  
Tomohiro Usui ◽  
Masashi Shidare ◽  
...  
Keyword(s):  
Silica Glass ◽  
Large Body ◽  
Aqueous Environment ◽  
Martian Surface ◽  
Exafs Analysis ◽  
Martian Meteorite ◽  
Fe Species ◽  
Allan Hills 84001 ◽  
X Ray Absorption

The aqueous environment of ancient Mars is of significant interest because of evidence suggesting the presence of a large body of liquid water on the surface at ~4 Ga, which differs significantly from the modern dry and oxic Martian environment. In this study, we examined the Fe-bearing minerals in the 4 Ga Martian meteorite, Alan Hills (ALH) 84001, to reveal the ancient aqueous environment present during the formation of this meteorite. Extended X-ray absorption fine structure (EXAFS) analysis was conducted to determine the Fe species in ALH carbonate and silica glass with a high spatial resolution (~1–2 μm). The μ-EXAFS analysis of ALH carbonate showed that the Fe species in the carbonate were dominated by a magnesite-siderite solid solution. Our analysis suggests the presence of smectite group clay in the carbonate, which is consistent with the results of previous thermochemical modeling. We also found serpentine in the silica glass, indicating the decrease of water after the formation of carbonate, at least locally. The possible allochthonous origin of the hematite in the carbonate suggests a patchy redox environment on the ancient Martian surface.

On the determination of true dissolution rate parameters from rotating disc experiments

1983 ◽  
Vol 15 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Martin Nicklasson ◽  
Arne Brodin ◽  
Lars-Olof Sundelöf
Keyword(s):  
Dissolution Rate ◽  
Rotating Disc

Validation of RP-HPLC Method for Determination of Omeprazole in Dissolution Media and Application to Study in-vitro Release from Solid-SNEDDS

2021 ◽  
Vol 17 ◽  
Author(s):  
Suhair S. Al-Nimry ◽  
Khouloud A. Alkhamis ◽  
Bashar M. Altaani
Keyword(s):  
Dissolution Rate ◽  
Phosphate Buffer ◽  
Water Solubility ◽  
In Vitro Release ◽  
Hplc Method ◽  
In Vitro Dissolution ◽  
Limit Of Quantification ◽  
Rp Hplc

Background: Omeprazole has poor water solubility, is unstable in acidic solutions, and undergoes first pass metabolism which results in lowering its bioavailability. A solid Self-Nano Emulsifying Drug Delivery System (SNEDDS) was previously prepared to enhance its dissolution. Objective: Development and validation of a RP-HPLC method with UV detection for the determination of omeprazole in 0.1N HCl and in 0.01 M phosphate buffer (pH 7.4). Methods: Validation was according to the ICH Q2 (R1) guidelines in terms of linearity, accuracy and precision, lower limit of quantification, sensitivity, specificity, and robustness. The developed and validated method was used to study the in-vitro dissolution of the drug from the solid-SNEDDS, commercial products and of the unprocessed drug. The dissolution was studied in 500 ml of 0.1N HCl during the first 2 hours, and 900 mL of 0.01 M phosphate buffer (pH 7.4) during the last hour (37 ± 0.5 oC and 100 rpm). Results: The method was linear in the range 1-50 μg/ml, accurate and precise as indicated by the ANOVA test. It was specific to the drug and the pharmaceutical excipients did not affect the determination of its concentration. The method was robust to small changes in pH, composition, and flow rate of the mobile phase. The dissolution rate of omeprazole from the Solid-SNEDDS was faster than that from two commercial dosage forms and than the dissolution rate of the unprocessed drug. Conclusion: The method met the acceptance criteria and was applied successfully in studying the rate of dissolution of the drug.

Sign in / Sign up

Export Citation Format

Share Document