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.     

Coupled nonparametric shape and moment-based intershape pose priors for multiple basal ganglia structure segmentation

This paper presents a new active contour-based, statistical method for simultaneous volumetric segmentation of multiple subcortical structures in the brain. In biological tissues, such as the human brain, neighboring structures exhibit co-dependencies which can aid in segmentation, if properly analyzed and modeled. Motivated by this observation, we formulate the segmentation problem as a maximum a posteriori estimation problem, in which we incorporate statistical prior models on the shapes and intershape (relative) poses of the structures of interest. This provides a principled mechanism to bring high level information about the shapes and the relationships of anatomical structures into the segmentation problem. For learning the prior densities we use a nonparametric multivariate kernel density estimation framework. We combine these priors with data in a variational framework and develop an active contour-based iterative segmentation algorithm. We test our method on the problem of volumetric segmentation of basal ganglia structures in magnetic resonance images. We present a set of 2-D and 3-D experiments as well as a quantitative performance analysis. In addition, we perform a comparison to several existent segmentation methods and demonstrate the improvements provided by our approach in terms of segmentation accuracy.     

On Lyapunov-type inequality for quasilinear systems

In this paper, we sketch some recent developments in the theory of Lyapunov-type inequalities and present some new results relating to a quasilinear system, special cases of which contain some well-known differential equations such as half-linear and linear equations. Our result generalize the Lyapunov-type inequality given in [18].     

Optically active tertiary alcohols by biocatalysis

Initially, chemoenzymatic route to optically active aromatic ring-fused cyclic tertiary alcohols (S)-(–)-1-methyl-1,2,3,4-tetrahydronaphthalen-1-ol-(–)-1b, (S)-(+)-1-methyl-2,3-dihydro-1H-inden-1-ol-(+)-1a has been reported.^[9 Özdemirhan, D.; Sezer, S. Sönmez, Y. Tetrahedron Asymmetry 2008, 19(23), 2717–2720.[Crossref], [Web of Science ®] , [Google Scholar]^] CAL-A (lipase-A from Candida antarctica) was found the best biocatalyst for 1b, CAL-A cross linked enzyme aggregate (CLEA) for 1a, with ee values of 20 and 45% and the esters 2b and 2a with ee values 99 and 71%. Then, cyclopent-2-ene anchored tertiary allyl 1a′, homoallyl 1b′ and homopropargyl 1c alcohols have been enzymaticly resolved in a high ee (up to 90%) with 44, 40, and 43% chemical yield, respectively, cyclohex-2-ene anchored tertiary allyl 3a, homoallyl 3b, and homopropargyl 3c alcohols in high ee (up to 97%) too with 42, 45, and 49% chemical yield in turn. Chiral dienes yield the spirocyclic dihydropyrans through ring-closing methathesis with 74 and 78% chemical yields with 90 and 97% ee. Chiral enynes afford the cyclopentenone pyrans through Pauson–Khand reaction with 80 and 81% chemical yields as single diastereomers as reported subsequently.^[1a (a) Tanyeli, C.; Özdemirhan, D. Tetrahedron Asymmetry 2014, 25(8), 658–666; (b) Gassoline, F.; Britton, R. A.; Mowat, J.; O’shea, P. D.; Davies, I. W. Synlett 2007, 14, 2193–2196; (c) Garcia, C.; Martin, V. S. Curr. Org. Chem. 2006, 10(14), 1849–1889; (d) Fujino, A.; Asano, M.; Yamaguchi, H.; Shirasaka, N.; Sakoda, A.; Ikunaka, M.; Obata, R.; Nishiyama, S.; Sugai, T. Tetrahedron Lett. 2007, 48(6), 979–983.[Crossref], [Web of Science ®] , [Google Scholar]^]     

Lyapunov-type integral inequalities for certain higher order differential equations

In this paper, first we will give a short survey of the most basic results on Lyapunov inequality, and next we obtain this-type integral inequalities for certain higher order differential equations. Our results are sharper than some results of Yang (2003) [20].