Tropical Peatland Hydrology Simulated With a Global Land Surface Model.

Tropical peatlands are among the most carbon-dense ecosystems on Earth, and their water storage dynamics strongly control these carbon stocks. The hydrological functioning of tropical peatlands differs from that of northern peatlands, which has not yet been accounted for in global land surface models (LSMs). Here, we integrated tropical peat-specific hydrology modules into a global LSM for the first time, by utilizing the peatland-specific model structure adaptation (PEATCLSM) of the NASA Catchment Land Surface Model (CLSM). We developed literature-based parameter sets for natural (PEATCLSMTrop,Nat) and drained (PEATCLSMTrop,Drain) tropical peatlands. Simulations with PEATCLSMTrop,Nat were compared against those with the default CLSM version and the northern version of PEATCLSM (PEATCLSMNorth,Nat) with tropical vegetation input. All simulations were forced with global meteorological reanalysis input data for the major tropical peatland regions in Central and South America, the Congo Basin, and Southeast Asia. The evaluation against a unique and extensive data set of in situ water level and eddy covariance-derived evapotranspiration showed an overall improvement in bias and correlation compared to the default CLSM version. Over Southeast Asia, an additional simulation with PEATCLSMTrop,Drain was run to address the large fraction of drained tropical peatlands in this region. PEATCLSMTrop,Drain outperformed CLSM, PEATCLSMNorth,Nat, and PEATCLSMTrop,Nat over drained sites. Despite the overall improvements of PEATCLSMTrop,Nat over CLSM, there are strong differences in performance between the three study regions. We attribute these performance differences to regional differences in accuracy of meteorological forcing data, and differences in peatland hydrologic response that are not yet captured by our model.

Colorimetric determination of procainamide in injectable preparations.

A simple, rapid colorimetric method is described which determines procainamide in commercially available, injectable solutions. It is based on complexing the drug with cupric ion and then measuring the absorption at 380 nm. The reaction is fast and the metal-drug ratio in the complex is 1:1. The pH optimum for maximum reaction is 4.0-4.5 which is maintained by an acetate buffer. Linear standard curves were obtained from 1.52 to 6.06 mg/mL. Analysis of 29 commercial samples resulted in an average of 97.3% of the label claim.

A GLC and GC/MS study of the reaction between benzylpenicillin and BF3-methanol.

A study of the reaction of BF3-methanol with benzylpenicillin showed that penicillin could be converted to a form suitable for gas-liquid chromatography. This study indicated possible use of the reaction in an analytical method for penicillin, by determining the methyl phenylacetate product. A reaction rate and yield study was conducted using gas-liquid chromatography employing an internal standard for improved measurement accuracy. The reaction gave a relatively constant yield of 70 +/- 2% and was complete in less than 1 minute. Investigations of the identity of side products were conducted using GC/MS, UV, and IR. A variety of products, including penicillenates, penillates, penilloates, and acrylic acid esters, were indicated at very mild reaction conditions.

Monitoring of benzylpenicillin decomposition in gastric contents by capillary zone electrophoresis.

A method has been developed to follow the decay of the antibiotic penicillin, specifically penicillin G or benzylpenicillin, in the gastric contents of laboratory rats. Purification by centrifugation and DEAE cellulose treatment of the stomach contents (diluted with pH 9 phosphate-borate buffer) was sufficient to allow the quantification of penicillin by capillary zone electrophoresis. An internal standard was used to minimize the injection error. The loss of activity was greater in fasted animals, as expected from the lower pH of their gastric contents, than in fed rats. The in vivo kinetics of the decomposition of the antibiotic was compared to that obtained in water and in hydrochloric acid solutions.

Design and optimization of a capillary electrophoretic mobility shift assay involving trp repressor-DNA complexes.

An investigation of DNA-protein interactions by capillary electrophoresis (CE) with laser fluorometric detection is performed that combines the rapid and minimal sample consumption methods of CE with the selective separation influence of mobility shift assays. An inspection of the well characterized interaction between the trp repressor of Escherichia coli and the trp operator (DNA) is the basis of the assay. The use of fluorescently tagged operator not only lends itself to laser-induced fluorescence detection but also precludes the use of radiolabeled detection. It is demonstrated that composition and pH of the running buffer are critical for maximized efficiency and resolution of operator from the repressor-operator complex. Quantitative studies showed reaction of repressor with operator resulted in the diminishing of free operator signal and the simultaneous creation of the repressor-operator peak that is well resolved from the free operator. Also examined was the ability to perform qualitative studies involving non-specific interactions between the operator and a complex protein sample. It is shown that the specificity of operator for repressor can be used to selectively separate the repressor from a complex sample that includes non-specific proteins.