Search

Summary: Fast Fourier transform (FTT) and nonlinear regression analysis are established analysis methods in the context of reflectometric layer thickness determination on thin transparent films. Where applicable, FFT is a very fast method for determining film thickness, but with limitations in resolution. The far more complex nonlinear regression analysis provides more accurate results. But it also has its problems which are discussed here. [ABSTRACT FROM AUTHOR]

Abstract: The determination of the thickness of thin transparent films with reflectometry is a well‐established cost‐effective robust method that can be used even in inline measurements. The method is based on measurements of the reflectance of the film and a numerical evaluation of the reflectance either by fast Fourier transform or nonlinear regression. In both cases the significance of the result depends upon several parameters in the used algorithms. We demonstrate how reliable the obtained thickness values are. [ABSTRACT FROM AUTHOR]

Die diskrete Fouriertransformation in Form der Schnellen Fouriertransformation (Fast Fourier Transform FFT) basiert auf zwei unabhängigen Variablen ν und t. Bei der Schichtdickenmessung ist diese Unabhängigkeit nicht mehr gegeben, weil der Brechungsindex n des Schichtmaterials eine Funktion von ν ist, n = n(ν), wodurch die Variable t auch eine Funktion von ν wird, t = t(ν). Dieses Problem verstärkt insbesondere den Leakage-Effekt der diskreten Fouriertransformation und führt zu Fehlern in der Dickenbestimmung von bis zu 5 % bei hochbrechenden Materialien wie Silizium. Eine einfache, aber effiziente Korrektur der Formel zur Schichtdickenberechnung in der FFT führt zur Reduktion des Fehlers auf unter 2 % bei hochbrechenden Materialien und unter 1 % bei allen anderen Materialien. [ABSTRACT FROM AUTHOR]

For determination of film thickness with a reflectometer, the incident light is usually perpendicular to the film. Often, however, measuring heads are used that keep the aperture of the optical fiber constant or even microscopes are used to increase the lateral resolution in film thickness determination. Analogous to a fixed angle of incidence α the thickness determination is influenced in both cases. In contrast to a fixed angle now all angles between 0° and the aperture angle αapt are present for a measuring head or a microscope objective. We demonstrate here, how the aperture of the measuring head affects the thickness determination and give a quantitative estimation of the influence by assigning an effective angle of incidence αeff to a measuring head with aperture angle αapt. [ABSTRACT FROM AUTHOR]

Examines agglomeration of nano-MgAl[sub2]O[sub4] spinel from microemulsion (ME) and chemical vapor deposition (CVD) technique. Discussion of the CVD process; Influence of CVD the target temperature on the tendency towards agglomeration during CVD synthesis; Obtainment of ME materials in the form of amorphous non-agglomerated particles.

Objectives: To explore and characterize the disposition and dynamics of micromotions in the wall of the intact resting teradotoxinized urinary bladder of the rabbit before and after the administration of adrenergic and cholinergic pharmaceutical agents. Methods: Spatiotemporal maps and related intravesical pressure were used to analyse propagating patches of contractions (PPCs) and their component individual myogenic contractions [propagating individual contractions (PICs)] in the wall of the tetradotoxinized urinary bladder. Results: The bladder wall exhibited two contractile states that were of similar frequencies to those of the two types of electrophysiological discharge described in previous studies; the first, in which cyclic PPCs predominated, the second in which small irregular PICs predominated. The addition of carbachol increased the size, frequency, speed and distance of propagation of PPCs, whereas the addition of isoprenaline temporarily halted the incorporation of PICs into PPCs, and reduced patch size and total area undergoing contraction. The RhoA kinase (ROCK) inhibitor Y‐27632 reduced both largest patch index and mean patch size. Both carbenoxolone and ROCK inhibition decreased the duration of PPCs. Carbenoxolone also prolonged duration and accelerated PPC propagation velocity. The authors postulate that these differences arise from differing effects of these agents on myocytes and interstitial cells within the stress environment of the bladder, influencing the development, coordination and propagation of PPCs. Conclusions: The timings and structure of spontaneous micromotions in the wall of the isolated bladder change when it is treated with sympathetic/parasympathetic agonists and with myogenically active agents. Correspondingly, disorders of bladder wall contraction may result from disorders of either neurogenic or myogenic signalling and may be amenable to treatment with combinations of agents that influence both. [ABSTRACT FROM AUTHOR]