Monitoring the curing processes of epoxy oligomers with partially substituted polyethoxymetallosiloxanes by IR spectroscopy and thermomechanical analysis

ABSTRACT A new computational technique for the thermomechanical analysis of tires in stationary rolling contact is suggested. Different from the existing approaches, the proposed method uses the constitutive description of tire rubber components, such as large deformations, viscous hysteresis, dynamic stiffening, internal heating, and temperature dependency. A thermoviscoelastic constitutive model, which incorporates all the mentioned effects and their numerical aspects, is presented. An isentropic operator-split algorithm, which ensures numerical stability, was chosen for solving the coupled mechanical and energy balance equations. For the stationary rolling-contact analysis, the constitutive model presented and the operator-split algorithm are embedded into the Arbitrary Lagrangian Eulerian (ALE)–relative kinematic framework. The flow of material particles and their inelastic history within the spatially fixed mesh is described by using the recently developed numerical technique based on the Time Discontinuous Galerkin (TDG) method. For the efficient numerical solutions, a three-phase, staggered scheme is introduced. First, the nonlinear, mechanical subproblem is solved using inelastic constitutive equations. Next, deformations are transferred to the subsequent thermal phase for the solution of the heat equations concerning the internal dissipation as a source term. In the third step, the history of each material particle, i.e., each internal variable, is transported through the fixed mesh corresponding to the convective velocities. Finally, some numerical tests with an inelastic rubber wheel and a car tire model are presented.

Download Full-text

A Comparative Study for Natural Degradation of Three Local Anesthetic Drugs for Human use by 1H NMR Relaxometry and FT-IR Spectroscopy

Studia Universitatis Babeș-Bolyai Physica ◽

10.24193/subbphys.2018.06 ◽

2018 ◽

Vol 63 (1-2) ◽

pp. 61-73

Author(s):

L. R. Drăgan ◽

◽

R. Crainic ◽

R. Fechete ◽

◽

...

Keyword(s):

Ir Spectroscopy ◽

Comparative Study ◽

Local Anesthetic ◽

Anesthetic Drugs ◽

Nmr Relaxometry ◽

Ft Ir ◽

Natural Degradation ◽

Human Use ◽

1H Nmr Relaxometry ◽

Ft Ir Spectroscopy

Download Full-text

First Nano-Infrared Spectroscopy and Imaging Measurements of Single Phospholipid Bilayers

10.26434/chemrxiv.5459617.v2 ◽

2018 ◽

Author(s):

Adrian Cernescu ◽

Michał Szuwarzyński ◽

Urszula Kwolek ◽

Karol Wolski ◽

Paweł Wydro ◽

...

Keyword(s):

Infrared Spectroscopy ◽

Ir Spectroscopy ◽

Absorption Band ◽

Spectral Region ◽

Near Field ◽

Phospholipid Bilayers ◽

Model Systems ◽

Absorption Bands ◽

Protein Complement ◽

20 Nm

<div><div>Scattering-mode Scanning Near-Field Optical Microscopy (sSNOM) allows one to obtain absorption spectra in the mid-IR region for samples as small as 20 nm in size. This configuration has made it possible to measure FTIR spectra of the protein complement of membranes. (Amenabar 2013) We now show that mid-IR sSNOM has the sensitivity required to measure spectra of phospholipids in individual bilayers in the spectral range 800 cm<sup>-1</sup>–1400 cm<sup>-1</sup>. We have observed the main absorption bands of the dipalmitoylphosphatidylcholine headgroups in this spectral region above noise level. We have also mapped the phosphate absorption band at 1070 cm<sup>-1</sup> simultaneously with the AFM topography. We have shown that we could achieve sufficient contrast to discriminate between single and multiple phospholipid bilayers and other structures, such as liposomes. This work opens the way to further research that uses nano-IR spectroscopy to describe the biochemistry of cell membranes and model systems.</div></div><div></div>

Download Full-text