Novel functional copolymers based on glycidyl methacrylate: Synthesis,characterization, and polymerization kinetics

A new methacrylate monomer 2-(4-nitrophenyl)-2-oxoethyl-2-methacrylate (NFM) was synthesized and its radical copolymerization with glycidyl methacrylate (GMA) was studied in 1,4-dioxane solution at 65°C using 2,2′-azobisisobutyronitrile as an initiator. The synthesized monomer and copolymers were characterized by FTIR, ¹H and ¹³C-NMR spectroscopy. The analysis of reactivity ratios revealed that NFM is less reactive than GMA, and copolymers formed are statistically in nature. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increasing in the mole fraction of NFM in the copolymers. Glass transition temperatures of the copolymers decreased with an increasing of NFM molar fraction in copolymers. In addition, according to the results obtained from the contact angle and zeta potential measurements the hydrophobic character of the polymer decreases (it means surface free energy increases) and its zeta potential becomes more negative with increase of NFM ratio in the copolymer. Polymers with carbonyl functional groups have been particularly interesting because of their use as photoresists.     

Lensing and waveguiding of ultraslow pulses in an atomic Bose-Einstein condensate

We investigate lensing and waveguiding properties of an atomic Bose-Einstein condensate for ultraslow pulse generated by electromagnetically induced transparency method. We show that a significant time delay can be controllably introduced between the lensed and guided components of the ultraslow pulse. In addition, we present how the number of guided modes supported by the condensate and the focal length can be controlled by the trap parameters or temperature.     

Kinetic and thermodynamic approaches on thermal degradation of sepiolite crystal using XRD-analysis

Journal of Thermal Analysis and Calorimetry - A method was proposed to use XRD-data for thermal analyses of crystalline solids. Therefore, the XRD-pattern was recorded for natural and preheated...     

The first enzymatic resolution of quaternary α′-acetoxy α,β-unsaturated cyclohexenones and cyclopentenones

The enantioselective resolution of various quaternary α′-acetoxy α,β-unsaturated cyclohexenones and cyclopentenones was performed with the commercially available enzyme CCL in pH = 8.0 phosphate buffer. Various parameters that would affect the enantioselectivities were tested and the best enzymatic resolution conditions were found to afford the enantiomerically enriched quaternary acetoxylated substrates with high ee varying between 36% and 99%.     

Statistics and probability theory in renewable energy: Teaching and research

In this paper, the key-role and utility of statistics and probability theory in the field of renewable energy are emphasized and illustrated via specific examples. It is demonstrated that renewable energy is a very suitable field to effectively teach and implement many statistical and probabilistic concepts and techniques. From a research point of view, statistical and probabilistic methods have been successfully employed in evaluating renewable energy systems. These methods will continue to be of core interest for the renewable energy sector in the future, as new and more complex renewable energy systems are developed and installed. In this context, some future research directions in relation to the evaluation of renewable energy systems are also presented.     

Reduction of conformational mobility and aggregation in W60G β2‐microglobulin: assessment by 15N NMR relaxation

The amyloid pathology associated with long‐term haemodialysis is due to the deposition of β₂‐microglobulin, the non‐polymorphic light chain of class I major histocompatibility complex, that accumulates at bone joints into amyloid fibrils. Several lines of evidence show the relevance of the tryptophan residue at position 60 for the fibrillogenic transition of the protein. A comparative ¹⁵N NMR relaxation analysis is presented for wild‐type human β₂‐microglobulin and W60G β₂‐microglobulin, i.e. the mutant with a glycyne replacing the natural tryptophan residue at position 60. The experimental data, collected at 11.4 T and 310 K, were analyzed by means of the reduced spectral density approach. Molecular dynamics (MD) simulations and corresponding thermodynamic integration, together with hydrodynamic calculations were performed to support data interpretation. The analysis results for the mutant protein are consistent with a reduced aggregation with respect to the wild‐type counterpart, as a consequence of an increased conformational rigidity probed by either NMR relaxation and MD simulations. Although dynamics in solution is other than fibrillar competence, the assessed properties of the mutant protein can be related with its reduced ability of forming fibrils when seeded in 20% trifluoroethanol. Copyright © 2013 John Wiley & Sons, Ltd.     

Integral averaging technique for the interval oscillation criteria of certain second-order nonlinear differential equations

We present new interval oscillation criteria related to integral averaging technique for certain classes of second-order nonlinear differential equations which are different from most known ones in the sense that they are based on the information only on a sequence of subintervals of [t₀,∞), rather than on the whole half-line. They generalize and improve some known results. Examples are also given to illustrate the importance of our results.     

Diffusion of Butylated Hydroxy Toluol (BHT) in PVC Films

Abstract

The diffusion coefficient of butylated hydroxy toluol (BHT) in solvent casted PVC films from tetrahydrofurane (THF) was studied by UV spectroscopy. Diffusion coefficient of BHT in PVC at 140, 160 and 180°C were determined as 1.0 × 10^?12 3.0 × 10^?12 and 6.0 × 10^?12 m²/s. The activation energy of diffusion (E_a) was 66 kj/mol.

IR spectroscopic work showed that the complete removal of THF was possible by heating films 15 minutes at 140 °C, but that caused formation of C=0 groups in PVC. No dehydrochlorination of films was observed even for heating them at 180 °C for 60 minutes.

Antioxidant BHT is volatile at high temperatures, so it is not advisable to use it for high temperature applications.     

Synthesis and characterization of liquid crystalline unsymmetrically substituted phthalocyanines

The synthesis of unsymmetrically substituted phthalocyanines bearing two p-tolyl-sulfonyl (tosyl)amido and six alkylthio moieties was achieved by cyclotetramerisation of two different phthalonitrile derivatives, namely 1,2-di(alkylthio)-4,5-dicyanobenzene and 4,5-dicyano-N,N′-ditosyl-o-phenylenediamine in the presence of an anhydrous metal salt and strong base. The new compounds were characterized by elemental analyses, UV/Vis, IR, NMR and mass spectra. The mesogenic properties of these new materials were studied by differential scanning calorimetry (DSC) and polarizing optical microscopy. The mesogenic properties of these compounds were compared to that of their symmetric analogous, octaalkythia substituted phthalocyanine derivatives.