Optical investigation of Sm(III)-β-diketonate complexes with different neutral ligands

Abstract Diffusing wave spectroscopy (DWS) in the backscattering geometry was employed to observe the evolution of the intensity correlation function during the acidification of skimmed milk by gluconic-δ-lactone (GDL). At the stage when the formation of casein particle gel is largely complete the correlation function at shorter decay times reveals the local structural arrest of the casein micelles, whereas at longer delay times it illustrates the hindered slow motion of casein micelle aggregates. We use the principles of the approach suggested by Mason, Gang and Weitz, linking the optically measured mean square displacement, <Δr2(t)>, of the microscopic particles in a dense colloid to its viscoelastic properties, to provide an estimate of the frequency dependent viscoelastic modulus of the acidified milk gel (AMG). We compare the viscoelastic moduli measured by the conventional mechanical rheometry with the optically measured ones. The results of the two different experimental methods are found to be in reasonable agreement.

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Optical Investigation of a Partial Fuel Stratification Strategy to Stabilize Overall Lean Operation of a DISI Engine Fueled with Gasoline and E30

Energies ◽

10.3390/en14020396 ◽

2021 ◽

Vol 14 (2) ◽

pp. 396

Author(s):

Cinzia Tornatore ◽

Magnus Sjöberg

Keyword(s):

Volume Fraction ◽

Direct Injection ◽

Combustion Process ◽

Pilot Injection ◽

Optical Investigation ◽

Flame Kernel ◽

Lean Combustion ◽

Fuel Stratification ◽

Spark Plug ◽

Initial Flame

This paper offers new insights into a partial fuel stratification (PFS) combustion strategy that has proven to be effective at stabilizing overall lean combustion in direct injection spark ignition engines. To this aim, high spatial and temporal resolution optical diagnostics were applied in an optically accessible engine working in PFS mode for two fuels and two different durations of pilot injection at the time of spark: 210 µs and 330 µs for E30 (gasoline blended with ethanol by 30% volume fraction) and gasoline, respectively. In both conditions, early injections during the intake stroke were used to generate a well-mixed lean background. The results were compared to rich, stoichiometric and lean well-mixed combustion with different spark timings. In the PFS combustion process, it was possible to detect a non-spherical and highly wrinkled blue flame, coupled with yellow diffusive flames due to the combustion of rich zones near the spark plug. The initial flame spread for both PFS cases was faster compared to any of the well-mixed cases (lean, stoichiometric and rich), suggesting that the flame propagation for PFS is enhanced by both enrichment and enhanced local turbulence caused by the pilot injection. Different spray evolutions for the two pilot injection durations were found to strongly influence the flame kernel inception and propagation. PFS with pilot durations of 210 µs and 330 µs showed some differences in terms of shapes of the flame front and in terms of extension of diffusive flames. Yet, both cases were highly repeatable.

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Optical investigation on tri-layers MoS2 thin film

10.1063/5.0017681 ◽

2020 ◽

Author(s):

Chandrabhan Dohare ◽

Premlata Yadav ◽

S. Ghosh

Keyword(s):

Thin Film ◽

Optical Investigation

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Tb3+-doped fluorescent glass for biology

Science Advances ◽

10.1126/sciadv.abd2529 ◽

2021 ◽

Vol 7 (2) ◽

pp. eabd2529

Author(s):

Kazuki Okamoto ◽

Teppei Ebina ◽

Naoki Fujii ◽

Kuniaki Konishi ◽

Yu Sato ◽

...

Keyword(s):

Single Cell ◽

Fluorescent Protein ◽

Biological Research ◽

Optical Investigation ◽

Patch Clamp Recording ◽

Rare Earth Ion ◽

Cell Transcriptome ◽

Green Fluorescent ◽

Doped Glass

Optical investigation and manipulation constitute the core of biological experiments. Here, we introduce a new borosilicate glass material that contains the rare-earth ion terbium(III) (Tb3+), which emits green fluorescence upon blue light excitation, similar to green fluorescent protein (GFP), and thus is widely compatible with conventional biological research environments. Micropipettes made of Tb3+-doped glass allowed us to target GFP-labeled cells for single-cell electroporation, single-cell transcriptome analysis (Patch-seq), and patch-clamp recording under real-time fluorescence microscopic control. The glass also exhibited potent third harmonic generation upon infrared laser excitation and was usable for online optical targeting of fluorescently labeled neurons in the in vivo neocortex. Thus, Tb3+-doped glass simplifies many procedures in biological experiments.

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In-Line Rheo-Optical Investigation of the Dispersion of Organoclay in a Polymer Matrix during Twin-Screw Compounding

Polymers ◽

10.3390/polym13132128 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2128

Author(s):

Paulo F. Teixeira ◽

José A. Covas ◽

Loïc Hilliou

Keyword(s):

Local Heating ◽

Polymer Nanocomposite ◽

Structural Rearrangement ◽

Particle Dispersion ◽

Optical Investigation ◽

Twin Screw Extrusion ◽

Clay Particles ◽

Clay Dispersion ◽

Screw Extrusion ◽

Twin Screw

The dispersion mechanisms in a clay-based polymer nanocomposite (CPNC) during twin-screw extrusion are studied by in-situ rheo-optical techniques, which relate the CPNC morphology with its viscosity. This methodology avoids the problems associated with post extrusion structural rearrangement. The polydimethylsiloxane (PDMS) matrix, which can be processed at ambient and low temperatures, is used to bypass any issues associated with thermal degradation. Local heating in the first part of the extruder allows testing of the usefulness of low matrix viscosity to enhance polymer intercalation before applying larger stresses for clay dispersion. The comparison of clay particle sizes measured in line with models for the kinetics of particle dispersion indicates that larger screw speeds promote the break-up of clay particles, whereas smaller screw speeds favor the erosion of the clay tactoids. Thus, different levels of clay dispersion are generated, which do not simply relate to a progressively better PDMS intercalation and higher clay exfoliation as screw speed is increased. Reducing the PDMS viscosity in the first mixing zone of the screw facilitates dispersion at lower screw speeds, but a complex interplay between stresses and residence times at larger screw speeds is observed. More importantly, the results underline that the use of larger stresses is inefficient per se in dispersing clay if sufficient time is not given for PDMS to intercalate the clay galleries and thus facilitate tactoid disruption or erosion.

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