scholarly journals Tailoring the Random Lasing Properties by Controlled Phase Separation Process in PMMA:PVK Dye-Doped Polymeric Blends

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3182
Author(s):  
Konrad Cyprych ◽  
Lech Sznitko
Keyword(s):  
Phase Separation ◽  
Relative Concentration ◽  
Emission Spectra ◽  
Spectral Shift ◽  
Phase System ◽  
Random Lasing ◽  
Double Phase ◽  
Wide Range ◽  
Threshold Conditions ◽  
Simple Phase

This article describes the random lasing (RL) phenomenon obtained in a dye-doped, polymeric double-phase system composed of PMMA and PVK polymers. It shows how relative concentrations between mentioned macromolecules can influence lasing parameters of the resulting blends, including obtained emission spectra and threshold conditions. We describe the influence of lasers’ composition on their morphologies and link them with particular RL properties. Our studies reveal that the disorder caused by phase separation can support the RL phenomenon both in the waveguiding and quasi-waveguiding regimes. Changing the relative concentration of polymers enables one to switch between both regimes, which significantly influences threshold conditions, spectral shift, number of lasing modes, and ability to support extended and/or localized modes. Finally, we show that a simple phase separation technique can be used to fabricate efficient materials for RL. Moreover, it enables the tailoring of lasing properties of materials in a relatively wide range at the stage of the laser material fabrication process in a simple way. Therefore, this technique can be seen as a fast, cheap, and easy to perform way of random lasers fabrication.

scholarly journals Tunable thermo-reversible bicontinuous nanoparticle gel driven by the binary solvent segregation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuyin Xi ◽  
Ronald S. Lankone ◽  
Li-Piin Sung ◽  
Yun Liu
Keyword(s):  
Phase Separation ◽  
Domain Size ◽  
Binary Solvent ◽  
Colloidal Systems ◽  
Colloidal Assembly ◽  
Structures And Properties ◽  
Wide Range ◽  
Equilibrium Process ◽  
Equilibrium Structures ◽  
Non Equilibrium

AbstractBicontinuous porous structures through colloidal assembly realized by non-equilibrium process is crucial to various applications, including water treatment, catalysis and energy storage. However, as non-equilibrium structures are process-dependent, it is very challenging to simultaneously achieve reversibility, reproducibility, scalability, and tunability over material structures and properties. Here, a novel solvent segregation driven gel (SeedGel) is proposed and demonstrated to arrest bicontinuous structures with excellent thermal structural reversibility and reproducibility, tunable domain size, adjustable gel transition temperature, and amazing optical properties. It is achieved by trapping nanoparticles into one of the solvent domains upon the phase separation of the binary solvent. Due to the universality of the solvent driven particle phase separation, SeedGel is thus potentially a generic method for a wide range of colloidal systems.

scholarly journals Melt-Spun Photoluminescent Polymer Optical Fibers for Color-Tunable Textile Illumination

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1740
Author(s):  
Konrad Jakubowski ◽  
Manfred Heuberger ◽  
Rudolf Hufenus
Keyword(s):  
Energy Transfer ◽  
Optical Fibers ◽  
Color Space ◽  
Emission Spectra ◽  
Wide Range ◽  
Color Tunable ◽  
Melt Spun ◽  
Polymer Optical Fibers ◽  
Collective Emission ◽  
Down Conversion

The increasing interest in luminescent waveguides, applied as light concentrators, sensing elements, or decorative illuminating systems, is fostering efforts to further expand their functionality. Yarns and textiles based on a combination of distinct melt-spun polymer optical fibers (POFs), doped with individual luminescent dyes, can be beneficial for such applications since they enable easy tuning of the color of emitted light. Based on the energy transfer occurring between differently dyed filaments within a yarn or textile, the collective emission properties of such assemblies are adjustable over a wide range. The presented study demonstrates this effect using multicolor, meltspun, and photoluminescent POFs to measure their superimposed photoluminescent emission spectra. By varying the concentration of luminophores in yarn and fabric composition, the overall color of the resulting photoluminescent textiles can be tailored by the recapturing of light escaping from individual POFs. The ensuing color space is a mean to address the needs of specific applications, such as decorative elements and textile illumination by UV down-conversion.

scholarly journals Intracellular Ionic Strength Sensing Using NanoLuc

2021 ◽  
Vol 22 (2) ◽  
pp. 677
Author(s):  
Tausif Altamash ◽  
Wesam Ahmed ◽  
Saad Rasool ◽  
Kabir H. Biswas
Keyword(s):  
Thermal Stability ◽  
Phase Separation ◽  
Drug Discovery ◽  
Ionic Strength ◽  
Cellular Signaling ◽  
Live Cells ◽  
Protein Activity ◽  
Cellular Survival ◽  
Cellular Processes ◽  
Wide Range

Intracellular ionic strength regulates myriad cellular processes that are fundamental to cellular survival and proliferation, including protein activity, aggregation, phase separation, and cell volume. It could be altered by changes in the activity of cellular signaling pathways, such as those that impact the activity of membrane-localized ion channels or by alterations in the microenvironmental osmolarity. Therefore, there is a demand for the development of sensitive tools for real-time monitoring of intracellular ionic strength. Here, we developed a bioluminescence-based intracellular ionic strength sensing strategy using the Nano Luciferase (NanoLuc) protein that has gained tremendous utility due to its high, long-lived bioluminescence output and thermal stability. Biochemical experiments using a recombinantly purified protein showed that NanoLuc bioluminescence is dependent on the ionic strength of the reaction buffer for a wide range of ionic strength conditions. Importantly, the decrease in the NanoLuc activity observed at higher ionic strengths could be reversed by decreasing the ionic strength of the reaction, thus making it suitable for sensing intracellular ionic strength alterations. Finally, we used an mNeonGreen–NanoLuc fusion protein to successfully monitor ionic strength alterations in a ratiometric manner through independent fluorescence and bioluminescence measurements in cell lysates and live cells. We envisage that the biosensing strategy developed here for detecting alterations in intracellular ionic strength will be applicable in a wide range of experiments, including high throughput cellular signaling, ion channel functional genomics, and drug discovery.

Activity coefficients, densities, dipole moments, and surface tensions of the system triethylamine–methylethylketone–water

1981 ◽  
Vol 59 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Alan N. Campbell
Keyword(s):  
Surface Layer ◽  
Dipole Moments ◽  
Phase System ◽  
Constant Composition ◽  
Two Phase ◽  
Three Phase ◽  
Wide Range ◽  
Isothermal System ◽  
Total Composition ◽  
Two Phases

The properties named in the title have been determined by standard methods. Viscosity, molar volume, and orientation polarisation all indicate abnormalities of the nature of association between the components.The most interesting result is that of surface tension which indicates that, in the case of the binary system triethylamine–water, a surface layer of constant composition is formed over a wide range of total composition. When, by a rise in temperature of two or three degrees, this layer becomes unstable, it splits into two phases of different composition. The surface layer may then be instantaneously reformed and so on. A mechanism for the generation of a two-phase system is thus established. The data for the three-phase, isothermal, system are not so convincing, for reasons that are suggested.

scholarly journals Gelation Impairs Phase Separation and Small Molecule Migration in Polymer Mixtures

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1576
Author(s):  
Biswaroop Mukherjee ◽  
Buddhapriya Chakrabarti
Keyword(s):  
Phase Separation ◽  
Rational Design ◽  
Surface Segregation ◽  
Multiscale Methods ◽  
Coarse Grained ◽  
Polymer Gel ◽  
Polymer Mixtures ◽  
Separation Processes ◽  
Surface Migration ◽  
Wide Range

Surface segregation of the low molecular weight component of a polymeric mixture is a ubiquitous phenomenon that leads to degradation of industrial formulations. We report a simultaneous phase separation and surface migration phenomena in oligomer–polymer ( O P ) and oligomer–gel ( O G ) systems following a temperature quench that induces demixing of components. We compute equilibrium and time varying migrant (oligomer) density profiles and wetting layer thickness in these systems using coarse grained molecular dynamics (CGMD) and mesoscale hydrodynamics (MH) simulations. Such multiscale methods quantitatively describe the phenomena over a wide range of length and time scales. We show that surface migration in gel–oligomer systems is significantly reduced on account of network elasticity. Furthermore, the phase separation processes are significantly slowed in gels leading to the modification of the well known Lifshitz–Slyozov–Wagner (LSW) law ℓ ( τ ) ∼ τ 1 / 3 . Our work allows for rational design of polymer/gel–oligomer mixtures with predictable surface segregation characteristics that can be compared against experiments.

Transmission Electron Microscopy (TEM) Observations of Phase-Separations of Gamma-Prime Precipitates in Ni-Al-Fe and Ni-Si-Fe Ternary Alloys

2007 ◽  
Vol 26-28 ◽  
pp. 1311-1314 ◽  
Author(s):  
M. Senga ◽  
H. Kumagai ◽  
Tomokazu Moritani ◽  
Minoru Doi
Keyword(s):  
Phase Separation ◽  
Volume Fraction ◽  
Heating Temperature ◽  
Ternary Alloys ◽  
Phase System ◽  
Precipitate Phase ◽  
Two Phase ◽  
Gamma Prime ◽  
Transmission Electron ◽  
The Difference

In Ni-13.0at%Si-3.1at%Fe alloy, when γ/γ’ two-phase microstructure formed at 1123 K is isothermally heated at 923 K which is lower than the temperature where the initial γ/γ’ microstructure forms, the phase-separation of γ/γ’ precipitate phase occurs and γ particles newly appear in each cuboidal γ’ precipitate. While in Ni-10.2at%Al-10.8at%Fe alloy, when γ/γ’ two-phase microstructure formed at 1023 K is isothermally heated at 1123 K which is higher than the temperature where the initial γ/γ’ microstructure forms, the phase-separation of γ’ precipitate phase takes place and γ particles newly appear in each cuboidal γ’ precipitate. Such appearance of new γ particles in γ’ precipitates can be explained by the difference in the volume fraction of γ phase that should exist in the γ/γ’ two-phase system depending on the heating temperature.

Recent Progress in the Studies of Gas-Liquid Two-Phase Flows at Microgravity Conditions

2003 ◽  
Author(s):  
Tomoji Takamasa ◽  
Takashi Hibiki
Keyword(s):  
Recent Progress ◽  
Interfacial Area ◽  
Phase System ◽  
Two Phase Flows ◽  
Two Phase ◽  
Interfacial Area Transport ◽  
Drift Flux ◽  
Wide Range ◽  
Microgravity Conditions ◽  
Heat Loads

In a thermal system of spacecraft, two-phase flow system now is an excellent alternative to the conventional single-phase system in transporting large amount of thermal energy at a uniform temperature regardless of variations in the heat loads. In addition, two-phase flows exist in a wide range of applications and enabling technologies in space. This report outlines recent progress in the studies of gas-liquid two-phase flows at microgravity conditions, especially for which regarding to interfacial area transport and drift flux.

A Model for Deposition of Metal Vapors From Multiple Targets on a Cylindrical Substrate

2009 ◽  
Author(s):  
Lakshmi Singh ◽  
Anil K. Kulkarni ◽  
Jogender Singh
Keyword(s):  
Physical Vapor Deposition ◽  
Ceramic Composite ◽  
Relative Concentration ◽  
Functionally Graded ◽  
Multiple Targets ◽  
Functionally Graded Composite ◽  
Metal Vapors ◽  
Wide Range ◽  
Materials Used ◽  
Process Prediction

The paper addresses a challenging problem of developing technology for heat exchanger tubes embedded in ceramic composite matrix. Functionally graded composite tubes, made using physical vapor deposition (PVD) process, are required to have diffusion barrier layers, withstand high temperature, and be impermeable to hydrogen. The work addresses mathematical modeling of the deposition of metallic vapors from multiple targets on a cylindrical substrate to simulate the PVD process in manufacturing such tubes. Materials used for the deposition are Molybdenum and Niobium because they have shown good formability, strength, toughness and ductility over a wide range of temperatures. Commercially available software FLUENT was used to model the process. Prediction of condensation of vapors from metal ingots occurs in varying proportion along the circumference of the tube, resulting in submicron layers of different materials of varying thicknesses being ingrained into each other. Results are presented for patterns of materials showing continuously changing relative concentration of deposited metals over a stationary and rotating cylindrical substrate.

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