Measurement and correlation of solubilities for trifluoromethylbenzoic acid isomers in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスThe solubilities of 2-, 3- and 4-trifluoromethylbenzoic acids in supercritical carbon dioxide were measured at 308.2, 313.2 and 323.2 K by a flow-type apparatus. The pressure range of the measurement was from 9 to 23 MPa. The enhancements of solubility by fluorination were markedly observed for 2- and 3-trifluoromethylbenzoic acids. The solubilities of 4-trifluoromethylbenzoic acids are almost the same as those of 4-methylbenzoic acid. The experimental data were correlated by the Peng-Robinson equation of state. The correlated results show good agreement with the experimental data by adjusting binary interaction parameters. The results can represent the tendency of solubility enhancement. The interaction parameter between carbon dioxide and 3-trifluoromethylbenzoic acid is smaller than that between carbon dioxide and 2-trifluoromethylbenzoic acid or methylbenzoic acid isomers. While the estimated sublimation pressure for 4-trifluoromethylbenzoic acid is smaller than those for the other compounds, the solubilities of 4-trifluoromethylbenzoic acids are almost the same as those of 4-methylbenzoic acid. The interaction parameter between carbon dioxide and 4-trifluoromethylbenzoic acid show the negative values. This fact indicates that the interaction between carbon dioxide and 4-trifluoromethylbenzoic acid is stronger than those between carbon dioxide and the other compounds. © 2004 Elsevier B.V. All rights reserved

Endogenous reference RNAs for microRNA quantitation in formalin-fixed, paraffin-embedded lymph node tissue

Lymph node metastasis is one of the most important factors for tumor dissemination. Quantifying microRNA (miRNA) expression using real-time PCR in formalin-fixed, paraffin-embedded (FFPE) lymph node can provide valuable information regarding the biological research for cancer metastasis. However, a universal endogenous reference gene has not been identified in FFPE lymph node. This study aimed to identify suitable endogenous reference genes for miRNA expression analysis in FFPE lymph node. FFPE lymph nodes were obtained from 41 metastatic cancer and from 16 non-cancerous tissues. We selected 10 miRNAs as endogenous reference gene candidates using the global mean method. The stability of candidate genes was assessed by the following four statistical tools: BestKeeper, geNorm, NormFinder, and the comparative ΔCt method. miR-103a was the most stable gene among candidate genes. However, the use of a single miR-103a was not recommended because its stability value exceeded the reference value. Thus, we combined stable genes and investigated the stability and the effect of gene normalization. The combination of miR-24, miR-103a, and let-7a was identified as one of the most stable sets of endogenous reference genes for normalization in FFPE lymph node. This study may provide a basis for miRNA expression analysis in FFPE lymph node tissue