Fourier Interferometry as Applied to Microspectrofluorometry and Fluorescence Imaging of Living Cells

Excitation-emission fluorescence spectroscopy and imaging are applied to studies of cellular metabolism and at the convergence of cellular differentiation, detoxification, transformation, and senescence. Metabolic activity, intracellular redox levels, and compartmentation are probed by coenzyme [NAD(P)H] transients and monochlorobimane for glutathione dehydrogenase. Gene expression or its failure in lysosomal disorders is identified with fluorogenic probes. The "multiorganelle detoxification complex" is visualized and investigated with cytotoxic agents. A kind of photoactivated "accelerated cellular senescence" is recognized by accumulation of Schiff bases. Conventional and novel mitochondrial probes are used to localize these organelles in Saccharomyces cerevisiae as a model for future studies in mammalian cells and to detect in these very cells the organelle interactions resulting from the action of mitochondria-toxic drugs. The potential of these studies for biotechnology and instrumentation relying on fibers and integrated optics is considerably enhanced by Fourier interferometry.     

Studies on polyesterification reactions: Calculation of the rates of reverse reactions

Reactions between dicarboxylic acids and diols in the melt and leading to an equilibrium yield quantitative results which may be applied to the kinetics of some partial reactions of polyesterification. The relationship of the rate constants of the forward and the reverse reaction as well as of the equilibrium constant furnish valid results both in the absence of catalyst and in the presence of acid or basic catalysts. The values obtained for the energy of activation of the forward and the reverse reaction and of the overall reaction (13 ± 1 kcal/mole) also are in good agreement.     

Quasisteady aero-acoustic response of orifices.

The low frequency response of orifices (slit, circular diaphragm, and perforated plate) in the presence of mean flow is well predicted by a quasisteady theory. A refinement is brought to the theory by considering a Mach number dependent vena contracta coefficient. The measurements of the vena contracta coefficient of a slit agree well with the simple analytical expression existing in the case of the Borda tube orifice. The measured scattering matrix coefficients do not depend strongly on the geometry of the element. If the frequency is increased the moduli remain relatively unaffected while the arguments exhibit a complex behavior which depends on the geometry. From these considerations an anechoic termination efficient at high mass flow is designed.     

Effects of combined photodynamic therapy and ionizing radiation on human glioma spheroids

The effects of combined photodynamic therapy (PDT) and ionizing radiation are studied in a human glioma spheroid model. The degree of interaction between the two modalities depends in a complex manner on factors such as PDT irradiation fluence, fluence rate and dose of ionizing radiation. It is shown that gamma radiation and PDT interact in a synergistic manner only if both light fluence and gamma radiation dose exceed approximately 25 J cm(-2) and 8 Gy, respectively. Synergistic interactions are observed only for the lower fluence rate (25 mW cm(-2)) investigated. The degree of interaction appears to be independent of both sequence and the PDT or ionizing radiation time intervals investigated (1 and 24 h). Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assays show that low-fluence rate PDT is very efficient at inducing apoptotic cell death, whereas neither high-fluence rate PDT nor ionizing radiation produces significant apoptosis. Although the mechanisms remain to be elucidated, the data imply that the observed synergism is likely not due to gamma-induced cell cycle arrest or to PDT-induced inhibition of DNA repair.     

Untersuchungen zur Resorption und Metabolisierung oral applizierter 15N-markierter Nukleinsäuren

Es wurden Untersuchungen zur Resorption und Metabolisierung ¹⁵N-markierter Hefe-RNS an Ratten durchgeführt. Die Bilanz der ¹⁵N-Ausscheidung in Urin und Kot ergab eine nahezu vollständige Resorption und eine äuβerst niedrige Inkorporation des Nukleinsäurestickstoffs. Da für die Bewertung des Proteinstoffwechsels neben der Gesamt-¹⁵ N-Ausscheidungsmenge im Urin die ¹⁵N-Menge der Harnstoff-bzw. Ammonium-Fraktion herangezogen wird, wurde die prozentuale Verteilung der Nukleinsäuremetabolite auf die Metabolitfraktionen im Urin untersucht. Aufgrund der dabei gewonnenen Erkenntnisse können die bei Proteinstoffwechseluntersuchungen unter Verwendung ¹⁵N-markierter Hefen bzw. nukleinsäurehaltigen Hefeproteinen erhaltenen Daten korrigiert werden.     

Fourier Interferometry as Applied to Microspectrofluorometry and Fluorescence Imaging of Living Cells

Excitation-emission fluorescence spectroscopy and imaging are applied to studies of cellular metabolism and at the convergence of cellular differentiation, detoxification, transformation, and senescence. Metabolic activity, intracellular redox levels, and compartmentation are probed by coenzyme [NAD(P)H] transients and monochlorobimane for glutathione dehydrogenase. Gene expression or its failure in lysosomal disorders is identified with fluorogenic probes. The "multiorganelle detoxification complex" is visualized and investigated with cytotoxic agents. A kind of photoactivated "accelerated cellular senescence" is recognized by accumulation of Schiff bases. Conventional and novel mitochondrial probes are used to localize these organelles in Saccharomyces cerevisiae as a model for future studies in mammalian cells and to detect in these very cells the organelle interactions resulting from the action of mitochondria-toxic drugs. The potential of these studies for biotechnology and instrumentation relying on fibers and integrated optics is considerably enhanced by Fourier interferometry.     

A Mössbauer Study of Austenitic Steel Originating from the Steam Generator of a VVER-440 Type Nuclear Reactor,Paks, Hungary

Real specimens after more than ten years of operation in the steam generator of a VVER-440 type nuclear reactor, Paks, Hungary have been studied. Conversion electron Mössbauer spectroscopy was used for phase analysis of the primary side surfaces of austenitic stainless steel pipes. From the measurements, we concluded that the surface layer of the pipes consisted of a thin (<100 nm) and highly iron depleted oxidic film of nickel and chromium rich compounds. The ratio of the metallic constituents was found to be substantially different from that of the bulk steel to a depth of about 1–1.5 microns as revealed by independent SEM-EDAX studies. These findings may most likely be attributed to the irradiation enhanced diffusion and selective dissolution of iron.The bulk steel was investigated by transmission Mössbauer spectroscopy and X-ray diffraction. The samples originated from different sections of the collector head of the steam generator representing different contact times with steam and liquid water. Besides the paramagnetic peak of austenite, the Mössbauer spectra contained a magnetic sextet of ferrite in various amounts. This difference in phase composition may be attributed to the combination of irradiation effect and different thermal stress.     

Acoustic forcing to simulate the plunging motion of an airfoil

An alternative to performing dynamic plunging measurements on an airfoil is presented, which is suitable for high reduced frequencies. Instead of physically displacing the airfoil, the flow is modulated by loudspeakers. The loudspeakers are tuned to the first transversal eigenfrequency of the wind tunnel, which results in a 2D acoustic field. The paper first describes the experimental investigation of the acoustic field without a main flow. Then results of acoustic field measurements are compared to a commercially available boundary-element method. The results of local pressure measurements on the airfoil are compared to predictions of a numerical solution of the Euler equations for in inviscid compressible flow. This solution includes the acoustic field. A strong point of the method is that the excitation amplitude can be varied easily.