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  • Analytical Chemistry and Spectroscopy  (5)
  • Crop Moisture Index  (1)
  • Poisson's ratio.  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    International journal of biometeorology 42 (1998), S. 10-15 
    ISSN: 1432-1254
    Schlagwort(e): Key words Remote sensing ; Maize ; Regional production assessments ; Satellite ; Crop Moisture Index
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geographie , Physik
    Notizen: Abstract  Large-scale assessments of crop conditions prior to harvest are critical for providing early estimates of production. Satellite and weather information provide the opportunity for near real-time crop monitoring. The objective of this research was to develop an operational assessment system for crop production utilizing data from these sources. Maize (Zea mays) production was assessed in 42 Crop Reporting Districts (CRDs) across the United States Corn Belt, which produce 60% of all maize grown in the United States. Satellite, climatolocal, and agricultural data were collected for 8 years, 1985–1992, and aggregated into CRDs. A model predicting the normalized maize yields for each CRD was developed that included as independent variables a satellite data variable, the Vegetation Condition Index, and a climatological variable, the Crop Moisture Index. This model explained approximately three-quarters (R 2=0.73) of the variation observed in the normalized yields, and was examined both for its accuracy and its timeliness in providing production estimates. Predicted seasonal yields were summed to provide a maize production estimate for the entire Corn Belt study region. Production estimates deviated from the final USDA statistics, which become available several months after harvest, by less than 10% for all eight growing seasons. In addition, the production estimates were available approximately 2 months prior to the completion of the maize harvest. This system has the potential for providing timely in-formation to organizations monitoring regional or global agricultural production for humanitarian or economic benefits.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 6 (1992), S. 244-247 
    ISSN: 0269-3879
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: CGS 18102A is a novel hexahydrobenzopyranopyridine that has a mixed pharmacological profile of 5-HT-1A agonist and 5-HT-2 antagonist properties. Based upon these mechanisms, the compound is predicted to have anxiolytic efficacy with possible efficacy in depression. Preclinical studies in the rat have shown the drug to be well absorbed and extensively metabolized. Because of the anticipated low plasma levels in humans a gas chromatography/mass spectrometry (GC/MS) analytical method has been developed and validated to determine plasma concentrations of CGS 18102A in early clinical studies. The method utilizes CGS 18416A as the internal standard. Samples (1 mL) were extracted with pentane:ethyl acetate (75:25, v:v). Extracts were then concentrated and analysed directly by GC/MS. Separation was accomplished on a methylsilicone capillary column (30 m × 0.32 mm i.d.). GC/MS was carried out under positive ion ammonia CI conditions, with selected ion monitoring of the [M + H]+ ions (m/z = 262 and 248) for CGS 18102A and CGS 18416A, respectively. The method was successively applied to the analysis of clinical samples from an ascending multidose safety and tolerability study conducted in six normal healthy male volunteers.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 6 (1992), S. 236-240 
    ISSN: 0269-3879
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: An analytical method has been developed for the determination of a new antiepileptic drug, CGS 18416A, in human plasma. CGS 18416A is a new anticonvulsant representative of a novel class of water-soluble agents being developed for the treatment of epilepsy. Preclinical trials indicate sustained efficacy at relatively low oral doses, indicating a need for a sensitive assay. The method is based on capillary gas chromatography/mass spectrometry and utilizes stable isotope-labelled CGS 18416A as the internal standard. Samples (1 mL) are acidified, then washed with pentane/ethyl acetate, followed by liquid/liquid extraction at pH 11 with pentane/ethyl acetate. Extracts are then concentrated and analysed directly by gas chromatography/mass spectrometry. Separation is accomplished on a thick film methylsilicone capillary column. Mass spectrometry was carried out under positive ion ammonia Cl conditions with selected ion monitoring of the protonated molecular ions (m/z = 248 and 252) for CGS 18416A and the 13CD3-CGS 18416A, respectively. Specificity was demonstrated by the lack of interfering peaks at the retention time of CGS 18416A and the internal standard. Recovery and reproducibility assessments indicate good accuracy and precision over the validated concentration range of 0.2-51 ng/mL. The limit of quantification is 0.2 ng/mL and the method has sufficient sensitivity to support clinical trials. This is illustrated with an example of quantification in a normal volunteer following oral dosing.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 1005-1009 
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A capillary gas chromatography/mass spectrometry (GC/MS) method for the quantitative analysis of arecoline in plasma has been developed for concentrations in the range 1-50 ng ml-1. Hexadeuterated arecoline was utilized as the internal standard. The removal of drug from plasma was accomplished by a two-step liquid/liquid extraction procedure involving a wash step followed by extraction with 5% triethyl amine in ethyl acetate. The GC/MS determinations were carried out with temperature-programmed capillary GC and ammonia chemical ionization mass spectrometry. The [M + H]+ ions of both analyte and internal standard were monitored at m/z 156 and 162, respectively. The method is linear and has sufficient sensitivity, precision, accuracy and selectivity for analysis of drug levels in human plasma.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of elasticity 50 (1998), S. 87-89 
    ISSN: 1573-2681
    Schlagwort(e): elasticity ; moduli ; anisotropic material ; orthorhombic symmetry ; Poisson's ratio.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract An example of an orthorhombic material is constructed such that even though the strain-energy density is positive definite, Poisson's ratio may take an arbitrarily large positive value for one pair of orthogonal directions and take an arbitrarily small negative value for another pair of orthogonal directions.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An analytical method has been developed and validated for the quantitative determination of the N-methyl-D-aspartate (NMDA) antagonist cis-4-phosphonomethyl-2-piperidine carboxylic acid (CGS 19755) in human plasma. It is a member of a new class of compounds with the potential to be neuroprotective and attenuate neuronal damage resulting from brain trauma caused by stroke and head trauma. The method is based on gas chromatography/mass spectrometry and uses stable-isotope labeled CGS 19755 as the internal standard. Samples (1 ml) were first acidified (pH 2), then extracted using a solid-phase aminopropyl ion exchange column. The drug was eluted with NH4OH and evaporated until dry. Extracts were derivatized with a mixture of pentafluoropropionic anhydride and pentafluoropropanol, and analyzed by gas chromatography/mass spectrometry. Separation was accomplished on a DB-225 capillary column (15 m × 0.32 mm) with a 0.25 μ film thickness. Mass spectrometry was carried out under negative ion ammonia chemical ionization conditions with selected ion monitoring at m/z 760 and 764 for derivatized CGS 19755 and the internal standard, respectively. Specificity was shown by the lack of interfering peaks at the retention time of CGS 19755 and internal standard. Recovery and reproducibility assessments show good accuracy, precision and linearity over the validated concentration range of 2-5000 ng ml-1.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An analytical method has been developed for the simultaneous determination of a novel orally active angiotensin-converting enzyme inhibitor (CGS 16617) and a stable isotope-labeled analog. Both compounds are isolated from human plasma using an ion-exchange column, derivatized with pentafluoropropionic anhydride and pentafluoropropanol, and analyzed by gas chromatography/mass spectrometry. After splitless injection on a methyl-silicon column, the compound is detected using negative ion chemical ionization with nitrous oxide as a reagent gas. CGS 16617 labeled with four deuteriums and two 13C is used as an internal standard. The accuracy and precision of the method, expressed as the overall mean ± SD recovery obtained from two sets of 36 quality-control samples used during a clinical study (concentration range 0.2-100 ng ml-1 plasma), was 96.1 ± 16.2% for unlabeled drug and 97.6 ± 14.4% for the D4-labeled drug (concentration range 0.2-100 ng ml-1 plasma). The limit of quantification using 1 ml plasma is 0.2 ng ml-1 for both labeled and unlabeled drug.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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