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  • 1
    Electronic Resource
    Electronic Resource
    High-resolution x-ray and transmission electron microscopic analysis of a GaInAsSb/AlGaAsSb multiple quantum well laser structure (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 7664-7670 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-resolution x-ray diffractometry (HRXRD) and transmission electron microscopy (TEM) are employed to characterize a quaternary IIIxIII1−xVyV1−y AlGaAsSb/GaInAsSb multiple quantum well (MQW) heterostructure. A method for uniquely determining the chemical composition of the strained quaternary quantum well, information previously thought to be unattainable using HRXRD, is thoroughly described. The misconception that HRXRD can separately find the well and barrier thickness of a MQW from the pendellosung fringe spacing is corrected and, thus, the need for TEM is motivated. Computer simulations show that the key in finding the well composition is the intensity of the higher order satellite peaks in the diffraction pattern. For the AlGaAsSb/InGaAsSb MQWs analyzed in this work, the variation in the intensity of the third-order satellite peak is identified as a sensitive measure of the quantum well composition. Using HRXRD on an MQW semiconductor laser device layer, the ability to resolve this higher order peak and interpret the information contained in it is demonstrated for the first time. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370569
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  • 2
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    The Role of the U.N. in the Financing of Under-developed Economies (1963)
    Philadelphia : Periodicals Archive Online (PAO)
    Social studies. 54:2 (1963:Feb.) 59 
    Details
    ISSN: 0037-7996
    Topics: History
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:3111-1963-054-02-000005
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  • 3
    Electronic Resource
    Electronic Resource
    A model for the determination of carbamazepine clearance in children on mono- and polytherapy (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 359-362 
    Details
    ISSN: 1432-1041
    Keywords: Key words Carbamazepine ; Population pharmacokinetics ; Children ; NONMEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To derive a model describing carbamazepine (CBZ) clearance in children, in terms of individual patient characteristics. Methods: One hundred and eighteen steady-state serum carbamazepine concentration measurements were gathered during normal routine care of 72 compliant out-patients (2.3–16.3 years old). Levels were obtained from patients receiving monotherapy (55%), concomitant valproate (26%), or concomitant inducers (phenytoin, phenobarbitone; 19%). A one-compartment model was used to fit the data with the computer programme Nonlinear Mixed Effects Model (NONMEM). Results: Weight, age and concomitant medication were all important determinants of clearance. The final model for clearance (l · h−1) was: CL = [0.7(WT)0.4] · M, where WT is patient weight (kg) and M is a scaling factor for concomitant medication, with a value of 1 for patients on CBZ monotherapy or concomitant valproate and 1.4 for those receiving concomitant inducers. For the purposes of this analysis, bioavailability (f) was assumed to be complete, i.e., f is thus included in the term CL. Conclusions: CBZ clearance decreased with increasing age. As age and weight were correlated, either variable was a satisfactory predictor. The influence of both the inducers and valproate on CBZ clearance was as expected. This model, which describes clearance in terms of patient-specific details, can be used when predicting the maintenance dose required to achieve a target mean steady-state CBZ concentration in children.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050475
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of phenobarbitone population clearance values for South African children (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 381-383 
    Details
    ISSN: 1432-1041
    Keywords: Phenobarbitone ; children ; population pharmacokinetics ; NONMEM ; concomitant medication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Non-linear Mixed Effects Modelling (NONMEM) was used to estimate phenobarbitone population clearance values for South African children, using 52 serum levels gathered from 32 patients during their routine care. NONMEM was also used to evaluate the influence of fixed effects such as weight, age and concomitant medication. The final model describing phenobarbitone clearance was CL=[Exp(0.0288 Wt−2.53)] M, where CL=clearance (l·h−1), Exp=the base of the natural logarithm, Wt=patient weight (kg) and M=a scaling factor for concomitant medication with a value of 1 for patients on phenobarbitone monotherapy, 0.62 for those receiving concomitant valproate and 0.87 for those patients receiving concomitant carbamazepine or phenytoin. Mean (95% confidence interval) phenobarbitone clearance values were 7.6 ml·h−1·kg−1 (6.2, 9.0 ml·h−1·kg−1) for the monotherapy group, 5.0 ml·h−1·kg−1 (4.0, 6.0 ml·h−1·kg−1) in the presence of concomitant valproate and 6.8 ml·h−1·kg−1 (5.6, 8.0 ml·h−1·kg−1) in the presence of concomitant carbamazepine or phenytoin. These values are similar to those previously reported from both traditional and NONMEM pharmacokinetic studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194954
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  • 5
    Electronic Resource
    Electronic Resource
    Ions or photons — an assessment of the relationship between emission and mass spectrometry with the ICP (1986)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 324 (1986), S. 561-570 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A survey is given of the physical differences between the operation of the ICP used in AES and MS and the consequent differences in behaviour of the instrumentation resulting from the choice of atomic emission or mass spectrometry are discussed. Analytical performance is described in terms of detection limits, spectroscopic and non-spectroscopic interferences and matrix effects, and illustrated with some early comparative analytical studies recently completed. The conclusion is drawn that while yet a comparatively immature technique alongside ICP-AES, ICP-MS shows great promise as a multielement ultratrace analytical technique once it is widely understood and practiced. It is seen as a technique that complements and extends the older ICP spectrometries of AES and AFS rather than one which, except in a few cases, supercedes them.
    Notes: Zusammenfassung Eine Übersicht wird gegeben über die physikalischen Unterschiede beim Betrieb eines ICP in der Atom-Emissions-Spektrometrie (AES) und der Massenspektrometrie (MS). Sich daraus ergebende instrumentelle Konsequenzen werden diskutiert. Die analytischen Eigenschaften der jeweiligen Methoden werden bewertet anhand von Gütekriterien wie Nachweisgrenzen, spektroskopische und andere Störungen sowie Matrixeffekten. Hierzu dienen vorläufige, erst unlängst durchgeführte analytische Vergleichsuntersuchungen. Ihre Ergebnisse zeigen, daß die neue ICP-MS im Vergleich zu der älteren und inzwischen weitgehend ausgereiften ICP-AES durchaus große Aussichten hat als eine Multielementmethode für die extreme Spurenanalyse. Dazu müssen ihre Stärken voll erkannt und ausgenutzt werden. Von einigen Fällen abgesehen sollte sie die ICP-AES nicht ersetzen, sondern sinnvoll erweitern und ergänzen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00470412
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