Two-dimensional transient thermo-hydro-mechanical fundamental solutions of multiphase porous media in frequency and time domains

In this paper, the closed form two-dimensional fundamental solutions for a non-isothermal unsaturated deformable porous medium have been derived for a symmetric polar domain in both Laplace transform and time domains. The governing differential equations of the non-isothermal unsaturated soil consist of equilibrium, moisture, air and heat transfer equations including the suction effect, temperature effect and dissolved air in water. The derived fundamental solution has been verified mathematically by comparison with the previously presented corresponding fundamental solutions in three limiting cases including the steady-state thermo-hydro-mechanical, steady-state hydro-mechanical and elastostatic fundamental solutions. Also these 2D kernel functions are tested in comparison with a finite element method (FEM).     

Equilibrium shapes of flat knots

We study the equilibrium shapes of prime and composite knots confined to two dimensions. Using scaling arguments we show that, due to self-avoiding effects, the topological details of prime knots are localized on a small portion of the larger ring polymer. Within this region, the original knot configuration can assume a hierarchy of contracted shapes, the dominating one given by just one small loop. This hierarchy is investigated in detail for the flat trefoil knot, and corroborated by Monte Carlo simulations.     

Casimir forces, surface fluctuations, and thinning of superfluid film

Recent experiments on the wetting of 4He have shown that the film becomes thinner at the lambda transition and in the superfluid phase. The difference in thickness above and below the transition has been attributed to a Casimir interaction which is a consequence of a broken continuous symmetry in the bulk superfluid. However, the observed thinning of the film is larger than can be accounted by this Casimir force. We show that surface fluctuations give rise to an additional force, similar in form but larger in magnitude, which may explain the observations.     

Apex exponents for polymer-probe interactions

We consider self-avoiding polymers attached to the tip of an impenetrable probe. The scaling exponents gamma(1) and gamma(2), characterizing the number of configurations for the attachment of the polymer by one end, or at its midpoint, vary continuously with the tip's angle. These apex exponents are calculated analytically by epsilon expansion, and numerically by simulations in three dimensions. We find that when the polymer can move through the attachment point, it typically slides to one end; the apex exponents quantify the entropic barrier to threading the eye of the probe.     

Influence of temperature and light intensity on the photocuring process and kinetics parameters of a pigmented UV curable system

The photopolymerization of pigmented coatings is a great challenge and hardly investigated in the literature. Therefore, in this work, the effect of photopolymerization temperature and light intensity on the curing behavior of a TiO₂-pigmented UV curable epoxy acrylate system was investigated by using photo-differential scanning calorimetry (photo-DSC) analysis. The rate of conversion and ultimate conversion at four different temperatures (i.e., 25, 45, 65, and 85 °C) and four light intensities (i.e. 2, 20, 40 and 80 mW cm^?2) for unpigmented and pigmented formulations were measured. The effect of photo-polymerization temperature and light intensity on the kinetics constants was also evaluated. It was observed that the rate of conversion and final conversion values were affected by the temperature and UV-light intensity. It was seen that the rate of conversion and ultimate conversion had their maximum values at 65 °C for unpigmented formulations. However, in pigmented formulations, these two parameters improved by increasing the temperature even up to 85 °C. Increasing the temperature caused an increase in the amount of propagation and termination rate constants in both pigmented and unpigmented formulations although the changes in the pigmented formulation were more pronounced. It was observed that the rate of polymerization and ultimate conversion for unpigmented formulations increased by increasing the light intensity up to 20 mW cm^?2 and then decreased. On the other hand, it was found that these two parameters increased by increasing light intensity up to 40 mW cm^?2 when pigmented formulations used. Finally, the dependence of termination and propagation kinetics constants on light intensity was established for both unpigmented and pigmented coatings.     

Essential oil composition and antioxidant activity of different extracts of Nepeta betonicifolia C.A. Meyer and Nepeta saccharata Bunge

Aerial parts essential oil of Nepeta betonicifolia and N. saccharata were obtained by hydrodistillation and analysed by GC-FID and GC-MS. Thirty-three and eighteen components represented 97.9% and 98.2% of the total oils identified, respectively. Main compounds of the oil of N. betonicifolia were 4aα,7β,7aα-nepetalactone (42.0%), germacrene D (6.0%), triplal (5.2%), 1-nor-bourbonanone (4.0%) and 1,8-cineole (3.2%). The principal constituents of the essential oil of N. saccharata were found to be 4aβ,7α,7aβ-nepetalactone (66.9%), germacrene D (12.9%), sabinene (6.5%) and trans-caryophyllene (3.3%). The radical scavenging capacity (RSC) of methanol extracts and chloroform, butanol and water subfractions of aerial parts of N. betonicifolia and N. saccharata were evaluated by using DPPH, FRAP and ABTS assays. TPC of each extract was measured using Folin-Ciocalteau. The antioxidant activity of the butanolic subfractions of both plants was higher than other extracts examined.     

Functionalization of multi‐walled carbon nanotubes by the baclofen drug to immobilize palladium nanoparticles and catalyze Sonogashira coupling reactions

The baclofen‐MWCNTs‐Pd nanocatalyst was synthesized through covalent grafting of baclofen molecules onto surface‐modified carbon nanotubes and immobilizing Pd nanoparticles by the baclofen ligands. The chemical structure of the produced nanocatalyst was studied by Raman spectroscopy, Fourier transform‐infrared spectroscopy, energy‐dispersive spectroscopy (EDS), elemental mapping and inductively coupled plasma analysis. Also, its surface morphology was determined using the scanning and transmission electron microscopy techniques. Furthermore, the obtained baclofen‐MWCNTs‐Pd nanocatalyst is demonstrated to exhibit very high activity as a heterogeneous phosphine‐free catalyst in Sonogashira cross‐coupling of aryl halides by giving good to excellent yields of different products. In addition, the nanocatalyst can be reused four times without any significant leaching or loss of activity.