Light scattering from a waveguide structure with a sinusoidally corrugated boundary modulated by a weak roughness

Results are reported of the analysis of light scattering from a waveguide structure with a periodically and randomly distorted boundary. The method is based on the assumption of single scattering. The field inside the waveguide is analyzed within the framework of the geometrical optics approach. Results of a computer simulation are presented.     

‘Chirped’ grating coupler: a holographic approach

Based on a holographic approach an analysis of the chirped grating coupler is performed. Relations for the location of a focal line of a coupled out cylindrical wave for general construction parameters are obtained. Results of the analysis have been verified experimentally.     

Infrared absorption of glassy silicon dioxide

The infrared reflectivity of glassy silicon dioxide has been measured in the region of 2–35 m at room temperature. The reflectivity curve has been analyzed by means of Kramers-Kronig analysis and the optical constants have been determined. In addition to the three known peaks at 9 m, 12·5 and 22·5 m, the absorption curve exhibits further peaks at 17·5 and 11 m. A correlation with the transmissivity measurements has shown that in this region even the transmissivity curve exhibits a decrease. An attempt has been made at an interpretation of the spectrum according to Matossi's model of vibrations of the free tetrahedron SiO₄.The authors thanks Dr. A. Vako for enabling us to perform the measurement with the adapter for absolute reflectance and Dr. V. iek for his permission to use the computer programme and for stimulating discussions.     

A Series of Green Oxovanadium(IV) Precatalysts with O,N and S Donor Ligands in a Sustainable Olefins Oligomerization Process

Designing catalyst systems based on transition metal ions and activators using the principles of green chemistry is a fundamental research goal of scientists due to the reduction of poisonous solvents, metal salts and organic ligands released into the environment. Urgent measures to reduce climate change are in line with the goals of sustainable development and the new restrictive laws ordained by the European Union. In this report, we attempted to use known oxovanadium(IV) green complex compounds with O, N and S donor ligands, i.e., [VO(TDA)phen] • 1.5 H₂O (TDA = thiodiacetate), (phen = 1,10-phenanthroline), oxovanadium(IV) microclusters with 2-phenylpyridine (oxovanadium(IV) cage), [VOO(dipic)(2-phepyH)] • H₂O (dipic = pyridine-2,6-dicarboxylate anion), (2-phepyH = 2-phenylpyridine), [VO(dipic)(dmbipy)] • 2H₂O (dmbipy = 4,4′-dimethoxy-2,2′-dipyridyl) and [VO(ODA)(bipy)] • 2 H₂O (ODA = oxydiacetate), (bipy = 2,2′-bipyridine), as precatalysts in oligomerization reactions of 3-buten-2-ol, 2-propen-1-ol, 2-chloro-2-propen-1-ol and 2,3-dibromo-2-propen-1-ol. The precatalysts, in most cases, turned out to be highly active because the catalytic activity exceeded 1000 g mmol⁻¹·h⁻¹. In addition, the oligomers were characterized by Fourier-transform infrared spectroscopy (FTIR), matrix-assisted laser desorption/ionization (MALDI-TOF-MS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques.     

Holographic recording in photochromic CaF2 and its application to holographic interferometry

The holographic recording and read-out characteristics of the photochromic La-doped CaF₂ at 6328 Å are presented and some results of its application as a recording material in holograpic interferometry are given.     

Off-axis collimation of diode laser beams by means of single-element holographic diffractive optics

Principles of single-element holographic diffractive optics for collimation of diode laser beams with a large divergence, an elliptic cross-section, and astigmatism are presented. Holographic off-axis transformation enables collimation of the beam in two variants: one with a perpendicular input beam and an oblique output beam, and the other with the beams arranged vice-versa. Diffraction due to an elliptic aperture is analyzed. Inspection of experimental samples demonstrates an agreement with theory in the case of diffraction limited focal pattern and shows increase of astigmatism with the departure from diffraction only limitation.     

Graphische Bestimmung der optischen Konstanten aus Zwei DurchlÄssigkeiten

Ohne Zusammenfassung

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The initiation of necking in rectangular elastic/plastic specimens under uniaxial and biaxial tension

Necking in a rectangular parallelepiped of incompressible elastic/plastic material under uniaxia tension is studied as a bifurcation problem. Approximate upper-bound bifurcation stresses are found which show that bifurcation can occur immediately after the load on the specimen reaches a maximum if the length of the specimen is sufficiently great compared to the width and thickness. A simple formula applicable to sufficiently thin specimens is obtained for the approximate bifurcation stress. Sufficient conditions for uniqueness are found for elastic/plastic solids subjected to a general homogeneous stress-field. The particular case of the rectangular specimen under equal biaxial tension is investigated further, and the magnitude of the bifurcation stress is found to be very sensitive to the particular boundary conditions imposed.     

Technology of DTPA and immunoglobulins conjugation and their attachment to <Superscript>90</Superscript>Y and <Superscript>177</Superscript>Lu radionuclides

The aim of the study of labeling of ligand–antibody conjugates was to find optimal conditions of preparing of these conjugates and appropriate radioactivity of selected nuclide for applications in nuclear medicine. Conjugation of the γ-immunoglobulin G (human or bovine IgG, polyclonal antibodies) and bifunctional chelating agent, diethylenetriaminepentaacetic acid dianhydride (cDTPAA), was carried out. Various values of the cDTPAA/antibody ratio, the weight concentration of polyclonal or monoclonal antibodies (MEM-97) and buffers were used. Further, the labeling conditions of the DTPA–IgG conjugate by radionuclides ⁹⁰Y and ¹⁷⁷Lu were optimized, and the labeling yield and the conjugation ratio of prepared radionuclide–DTPA–IgG conjugates was determined. Optimal incubation time of the immunoglobulin conjugation was obtained at 30 min from mixing of individual components. The labeling yield of radionuclide–DTPA–antibody conjugate higher than 95% was achieved. Higher values of conjugation ratio of radionuclide–DTPA–antibody conjugate were achieved in 0.1 mol L⁻¹ carbonate buffer, pH 8.5, and the 0.1 mol L⁻¹ carbonate buffer is suitable for studied conjugation systems. This study showed that the labeling yield as well as the conjugation ratio of tested systems depend on the amount of antibody substance, bifunctional chelating agent/antibody molar ratio and pH value of the buffer used.     

Graphische Bestimmung der optischen Konstanten aus der Durchlässigkeit und dem Reflexionsvermögen einer planparallelen Probe

Ohne Zusammenfassung

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