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Simple Determination (simple + determination)
Selected AbstractsSimple Determination of Segment Numbers for Complex Polymer-Solvent SystemsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2007S. Machefer Abstract A theoretical analysis was made to show that segment numbers for complex polymers can be determined by interpreting pVT data in terms of an appropriate segment-based equation of state (EOS). Typically, experiments at high pressures have to be performed to obtain these data. In this study, pVT-derived properties, such as compressibility and speed of sound, together with isobaric specific volume measurements were used as an alternative data source. Experiments were carried out for polyol/water mixtures of different compositions. Taking account of the polymorphism of water, segment numbers were obtained by a numerical regression analysis. Mixture viscosities were calculated using an approved segment-based mixing rule and were in good agreement with experimental data over the temperature range of interest, indicating the validity of the determined segment numbers. [source] Simple determination of the herbicide napropamide in water and soil samples by room temperature phosphorescencePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2005Alfonso Salinas-Castillo Abstract A new, simple, rapid and selective phosphorimetric method for determining napropamide is proposed which demonstrates the applicability of heavy-atom-induced room-temperature phosphorescence for analyzing pesticides in real samples. The phosphorescence signals are a consequence of intermolecular protection and are found exclusively with analytes in the presence of heavy atom salts. Sodium sulfite was used as an oxygen scavenger to minimize room-temperature phosphorescence quenching. The determination was performed in 1 M potassium iodide and 6 mM sodium sulfite at 20 °C. The phosphorescence intensity was measured at 520 nm with excitation at 290 nm. Phosphorescence was easily developed, with a linear relation to concentration between 3.2 and 600.0 ng ml,1 and a detection limit of 3.2 ng ml,1. The method has been successfully applied to the analysis of napropamide in water and soil samples and an exhaustive interference study was also carried out to display the selectivity of the proposed method. Copyright © 2005 Society of Chemical Industry [source] Simple determination of huperzine A in human plasma by liquid chromatographic,tandem mass spectrometric methodBIOMEDICAL CHROMATOGRAPHY, Issue 1 2007Yun-Xia Li Abstract Huperzine A is a potent, reversible acetylcholinesterase inhibitor. In the present work, a rapid and sensitive LC,MS,MS method for the determination of huperzine A in human plasma using codeine phosphate as internal standard has been developed and validated. The analyte and internal standard were extracted from plasma using ethyl acetate, chromatographed on a C18 column (5 µm, 150 × 4.6 mm i.d.) with a mobile phase consisting of 1% formic acid,methanol (40:60, v/v), and detected using a tandem mass spectrometer with a TurboIonSpray ionization interface. The run time was only 2 min. Good linearity was achieved in the range 0.126 -25.2 ng/mL and the limit of detection in plasma was 0.064 ng/mL. The average recovery for huperzine A was 83.4% from plasma. The analytical sensitivity and accuracy of this assay is adequate for characterization of huperzine A in human plasma. Copyright © 2006 John Wiley & Sons, Ltd. [source] Simple determination of pirfenidone in rat plasma via high-performance liquid chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 12 2006Yongsheng Wang Abstract A simple, rapid and reliable high-performance liquid chromatographic method was developed and validated for the determination of pirfenidone and its major metabolites in rat plasma. Plasma proteins were precipitated with perchloric acid (10%, v/v) and the supernatant after centrifugation was determined using high-performance liquid chromatography. The analysis was carried out on a Lichrospher C18 column (250 × 4.6 mm i.d., 5 µm). The mobile phase consisted of acetonitrile,water containing 0.2% acetic acid (23:77, v/v) at a flow-rate of 1 mL/min. The eluant was detected at 310 nm. The calibration curves were linear over a concentration range from 0.15 to 76.67 µg/mL. The accuracy (relative error) of the assay ranged from -2.6 to 7.9% and the precision (coefficient of variation) was less than 4.5%. The established method has been successfully applied to a pharmacokinetic study of pirfenidone following a single oral dose to rats. Copyright © 2006 John Wiley & Sons, Ltd. [source] Bioluminescence imaging allows measuring CD8 T cell function in the liver,HEPATOLOGY, Issue 4 2010Dirk Stabenow In vivo evaluation of CD8 T cell effector (cytotoxic T lymphocyte [CTL]) function in peripheral organs such as the liver is currently not possible but would greatly improve our understanding of local immune regulation, because simple determination of antigen-specific CTL numbers does not predict the outcome of immune responses. In particular, measurement of alanine aminotransferase serum levels is not sensitive enough to detect T cell immunity against low numbers of target hepatocytes. We developed a procedure that detects virus-specific effector function of CTLs in the liver after simultaneous adenoviral transfer of reporter and immune target genes into hepatocytes, followed by bioluminescence imaging of reporter genes. Bioluminescence imaging enabled detection of as few as 10,000 infected hepatocytes in vivo, and even more importantly, quantification of antiviral effector function of as few as 50,000 CTLs. Conclusion: Our results provide evidence that low numbers of antigen-specific CTLs are sufficient to control viral gene expression and eliminate viral infection from hepatocytes. The experimental system established here is a highly sensitive method to simultaneously detect viral infection of hepatocytes and to quantify antiviral CTL function in the liver in vivo and will help in characterizing principles of hepatic immune regulation. (HEPATOLOGY 2010;51:1430,1437) [source] Noninvasive serum markers in the diagnosis of structural liver damage in chronic hepatitis C virus infectionLIVER INTERNATIONAL, Issue 9 2006Edison R. Parise Abstract: Aim: Several noninvasive markers are being used to assess the structural liver damage in patients with chronic hepatitis C (CHC). We evaluated the capacity of serum hyaluronic acid (HA), aspartate aminotransferase (AST)/ALT ratio, the AST to platelet ratio index (APRI) and ,-glutamyltransferase (GGT) levels to predict the intensity of hepatic fibrosis in patients with CHC. Patients and methods: In a total of 206 hepatitis C virus RNA-positive biopsied patients, AST, ALT, GGT levels, platelet count and serum HA concentration were determined. The APRI was calculated as the ratio of AST to platelets. Results: HA levels were best correlated with disease stage (r=,0.694; P<0.001). In the diagnosis of significant fibrosis (F2,F4), HA levels [AUC=0.879, 95% CI (0.832,0.927)] and APRI [AUC=0.824 (0.772,0.903)] were the markers with the best diagnostic accuracy. These parameters also best identified the presence of cirrhosis (F4), with an AUC of 0.908 (0.868,0.949) for HA and of 0.837 (0.772,0.903) for APRI. Conclusion: Serum HA was the parameter that alone presented the best diagnostic accuracy in the assessment of hepatic fibrosis in CHC. The APRI showed a better diagnostic sensitivity than GGT levels or the AST/ALT ratio. Its simple determination and low cost make this index a valid alternative for the noninvasive staging of CHC. [source] | |||||||||||||