Seven different nonlinear height (h)-diameter (d) models were developed and compared for brutian pine (Pinus brutia Ten.), black pine (Pinus nigra Arnold), and Taurus cedar (Cedrus libani A.Rich.) in southern Turkey. Residual analysis was conducted to identify the error structure. A weighting factor of w i =1/d was found to be appropriate for achieving the equal error variance assumption. The performance of the models was compared and evaluated based on 6 statistical criteria and residual analysis. Results suggested that the Gompertz model was superior to the other models in terms of its predictive ability. These tree species were located throughout the Mediterranean region, covering a wide range of topographic and climatic conditions. It is well known that height-diameter relationships depend heavily on local environmental conditions. Differences in the height-diameter relationship among and between ecoregions were tested using the nonlinear extra sum of squares method. Test results suggested that height-diameter models significantly differed between ecoregions, indicating that ecoregion-based height-diameter models are needed for prediction purposes. The ecoregion-based height-diameter models developed in this study may provide more accurate information for developing forest growth and yield models.
In this study, a new, sensitive and selective high-performance liquid chromatographic method was developed for the determination of meropenem (MEM) in human serum. In the developed method, C18 column (3.9 × 150 mm, 5 μm) was selected as stationary phase at 30°C, and methanol: acetic acid solution mixture was used as mobile phase with gradient program. Chromatographic separation was carried out at a flow rate of 1 mL/min, and detection was performed at 300 nm with diode array detector. Doripenem was selected as an internal standard, and the analytes were extracted from serum using protein precipitation method with ortho-phosphoric acid: methanol. Detection wavelength was selected as 300 nm. The developed method was validated according to International Council for Harmonisation (ICH) guidelines. The calibration curve was linear over a concentration range of 4–240 μg/mL with correlation coefficient of 0.9985. The limit of detection and limit of quantification values were found as 0.057 and 0.192 μg/mL, respectively. The validated method was successfully applied for the determination of MEM in human serum samples collected from patient volunteers at different time intervals, and therapeutic drug monitoring of MEM has been investigated.
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