Relaxation time of polypropylene glycol and polypropylene glycol dimethylether-like polymers in terms of fluid-phase temperature and pressure dependent hole fraction

2015 ◽  
Vol 68 ◽  
pp. 226-232 ◽  
Author(s):  
Ugur Yahsi ◽  
Bilgehan Coskun ◽  
Ayse Yumak ◽  
Karem Boubaker ◽  
Cumali Tav
Keyword(s):  
Relaxation Time ◽  
Fluid Phase ◽  
Polypropylene Glycol ◽  
Phase Temperature ◽  
Temperature And Pressure ◽  
Hole Fraction

Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1576-1586 ◽  
Author(s):  
Sara Pfister ◽  
Luca Sauser ◽  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen
Keyword(s):  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Core Region ◽  
Chlorin E6 ◽  
Polypropylene Glycol ◽  
Polymer Carriers ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Dynamic Methods ◽  
Derivatives Of

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

Investigation of the Rotary Lattice Mode in R2PtCl6 Compounds. II. From a Study of the 35Cl Nuclear Quadrupolar Spin–Lattice Relaxation

1971 ◽  
Vol 49 (19) ◽  
pp. 2389-2395 ◽  
Author(s):  
Robin L. Armstrong ◽  
Douglas F. Cooke
Keyword(s):  
Relaxation Time ◽  
Pressure Dependence ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Published Data ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
Lattice Mode ◽  
Temperature And Pressure

Measurements of the temperature and pressure variation of the 35Cl nuclear spin–lattice relaxation time in Rb2PtCl6 and Cs2PtCl6 are reported. The spin–lattice relaxation time is measured at atmospheric pressure for temperatures from 60 to 500 K and at four temperatures between 290 and 380 K for pressures to 5000 kg cm−2. Previously published data for K2PtCl6 are also included in the discussion. The Van Kranendonk theory of nuclear quadrupolar relaxation forms the basis of the analysis. The rotary lattice mode frequencies are deduced; they are of approximately the same magnitude and increase in the same sequence as the frequencies deduced from nuclear quadrupole resonance frequency measurements and from infrared and Raman data. An analysis of the pressure dependence of the spin–lattice relaxation time data yields order of magnitude pressure coefficients for the rotary mode frequencies. Finally, a thermodynamic analysis, which takes specific volume effects into account by incorporating both the temperature and pressure dependence of the data, is presented.

Temperature and pressure behavior of the structural relaxation time in glass formers

2002 ◽  
Vol 307-310 ◽  
pp. 264-269 ◽  
Author(s):  
R Casalini ◽  
S Capaccioli ◽  
M Lucchesi ◽  
M Paluch ◽  
S Corezzi ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Structural Relaxation ◽  
Pressure Behavior ◽  
Structural Relaxation Time ◽  
Temperature And Pressure

scholarly journals Slip Effects on MHD Convective Two-Phase Particulate Suspension Flow in a Convergent Channel

2018 ◽  
Vol 7 (4.10) ◽  
pp. 661
Author(s):  
S. Ramprasad ◽  
S. H.C.V.Subba Bhatta ◽  
B. Mallikarjuna
Keyword(s):  
Fluid Phase ◽  
Velocity Slip ◽  
Skin Friction Coefficient ◽  
Suspension Flow ◽  
Slip Parameter ◽  
Two Phase ◽  
Convergent Channel ◽  
Particulate Suspension ◽  
Slip Effects ◽  
Phase Temperature

In this article an attempt has been made to dscuss the velocity and temperature slip effects on MHD convective two phase particulate suspension flow in a convergent channel with viscous dissipation .The non dimensionalised governing equations are solved using Runge-Kutta shooting method.The results obtained are represented graphically for various emerging parameters.The skin friction coefficient and Nusselt number are obtained and validated with existing results.It is found that with an increase in velocity slip parameter the velocity of the fluid increases.The fluid phase temperature decreases with an increase in temperature slip parameter. 

Relaxation Behavior in Polystyrene Near and Above the Glass Transiton Studied by Ultrasonic Technique

1995 ◽  
Vol 407 ◽  
Author(s):  
A. Sahnoune ◽  
L. Piché
Keyword(s):  
Relaxation Time ◽  
Pressure Dependence ◽  
Relaxation Behavior ◽  
Ultrasonic Technique ◽  
The Real ◽  
Kauzmann Temperature ◽  
Temperature And Pressure ◽  
Fragility Parameter ◽  
Fragile Glass ◽  
Good Agreement

ABSTRACTWe report measurements of the temperature and pressure dependence of ultrasonic modulus in polystyrene between 340 and 550 K and applied pressures up to 775 bar. The real and imaginary parts of the modulus are analyzed within the Havriliak-Negami model and very good agreement is found over the entire temperature and pressure ranges. Using the Vogel-Tammann-Fulcher equation for the relaxation time, the Kauzmann temperature TK and the fragility parameter D of polystyrene were determined. The value of D indicates that polystyrene is a fragile-glass former.

Comparative study on electromagnetohydrodynamic single-wall carbon nanotube–water dusty nanofluid in the presence of radiation and Ohmic heating

2021 ◽  
pp. 095440892098573
Author(s):  
L Wahidunnisa ◽  
S Suneetha ◽  
SRR Reddy ◽  
P Bala Anki Reddy
Keyword(s):  
Electric Field ◽  
Phase Velocity ◽  
Thermal Radiation ◽  
Stagnation Point ◽  
Ohmic Heating ◽  
Fluid Phase ◽  
Stagnation Point Flow ◽  
Field Parameter ◽  
Dust Particles ◽  
Phase Temperature

The main intention of this article is to explore the significance of electronmagnetohydrodynamic (EMHD) dusty nanofluid on the stagnation point flow in the presence of radiation and Ohmic heating. Water is considered as base fluid with single-wall carbon nanotubes along with suspended dust particles. The numerical solutions for both dusty phase and fluid phase differential systems are obtained by using Runge Kutta 4th order with shooting method. Influence of embedded parameters such as Biot number, electric field, viscous dissipation, magnetic field, thermal radiation, Joule heating and stagnation point flow are presented graphically. Dust particles play a significant role in food pharmaceutical industries particularly for efficient cultivation of microorganisms and also these type of studies may be applicable in atmospheric fields, wastewater treatment, metal objects covered with plastic materials and solids drying. The higher values of electric field parameter ( E) increases the fluid phase velocity and dusty phase velocity. An increase in the thermal radiation parameter releases thermal energy into the flow, so this energy helps to increase the fluid phase temperature and dusty phase temperature. The fluid phase temperature and dusty phase temperature declines with increasing the electric field parameter for dusty fluid and dusty nanofluid cases.

Numerical Simulation and Experimental Investigation of Compression Processes of Two-Stage, very High Pressure Reciprocating Gas Compressors

1994 ◽  
Vol 208 (5) ◽  
pp. 287-298
Author(s):  
W H Hsieh ◽  
T T Wu
Keyword(s):  
High Pressure ◽  
Theoretical Model ◽  
Transient Flow ◽  
Numerical Code ◽  
Two Stage ◽  
Dead End ◽  
Compressor Performance ◽  
Phase Temperature ◽  
Temperature And Pressure ◽  
Very High

To help the design of more reliable and efficient two-stage, very high pressure reciprocating gas compressors, a theoretical model and a numerical code for simulating compression processes in the compressors were developed and validated. The theoretical model considers time-dependent conservation equations of species, mass and energy, the equation of state, kinematic relationships and various convective heat-transfer correlations The theoretical model was solved numerically. Experimentally, a 207 MPa (30 000 lb/in2) very high pressure gas compressor was instrumented for measurements of various transient flow properties. The experimental data were analysed to achieve a better understanding of the compression processes of the compressor as well as for model validation. A parametric study was conducted with the theoretical model and numerical code to investigate the effect of various compressor parameters on the compressor performance. Among the parameters studied, it was found that the dead-end volume had the strongest effect on the performance of the compressor. A reduced dead-end volume would increase the volumetric efficiency and the maximum gas-phase temperature and pressure in the first-stage cylinder.

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