Relationship between the hydration degree of poly-N-isopropylacrylamide gel and activity of immobilized α-chymotrypsin

The influence of the pH, temperature, and dimethyl sulfoxide concentration on the hydration degree of the poly-N-isopropylacrylamide gel and the activity of -chymotrypsin immobilized into the polymer was studied. The behavior of more hydrophilic preparations based on polyacrylamide and copolymer of acrylamide and acrylic acid was studied for comparison. An increase in both the temperature and dimethyl sulfoxide content decreases the hydration of the poly-N-isopropylacrylamide, which correlates with a decrease in the activity of the immobilized enzyme. The use of substrates with different structures and an irreversible inhibitor proves that the change in the properties of -chymotrypsin immobilized into the poly-N-isopropylacrylamide gel is related to the change in the rate constants of enzymatic reactions. Comparison of all experimental data obtained suggested an opportunity of local interactions between the protein globule and polymeric chains with a change in the hydration degree of poly-N-isopropylacrylamide during its phase transition.     

Reaction of 3H-perfluoroalk-2-enes with ammonia

3H-Perfluoroalk-2-enes react with aqueous ammonia to form polyfluorinated iminoenamines, from which hexafluoroacetylacetone and its analogs were synthesized.     

Zinc(II)-porphyrin Receptors in Multi-point Molecular Recognition: Recent Progress

The tremendous efforts made in order to control the coordination chemistry of hemoprotein models have considerably enhanced the synthesis of functionalized porphyrins, whose carefully designed architectures allowed for selective bindings of exogenic substrates. The common use of zinc(II) in place of pentacoordinated iron(II) has induced the use of zinc(II) porphyrins as building blocks for selective receptors. These receptors offer a convenient combination of multi-point recognition of substrates, and monitoring of the complexation due to the chromophoric nature of the tetrapyrrolic unit. This review is dedicated to recent progress made in the field of molecular recognition involving multi-point selective binding processes, in whichthe establishment of a strong coordination bond is finely tuned by one or more weak interactions adequately introduced in the architecture of a functionalized zinc(II)-porphyrin.     

Studies on the conformation of α-arylcinnamic acids and their esters: Crystal structures of methyl (E)-2,3-bis(3,4-dimethoxyphenyl)propenoate and methyl (Z)-2,3-bis(3,4-dimethoxyphenyl)propenoate

The conformations of stereoisomers of -arylcinnamic acids and their esters are discussed based on crystal structures of the E and Z forms of 2,3-bis(3,4-dimethoxyphenyl)propenoic acid and its methyl ester. In the E forms of the cinnamic acid and the cinnamic acid ester, the plane of the -aryl substituent is approximately perpendicular to that of the rest of the molecule. In the Z forms the plane of the carboxyl or methoxycarbonyl group is approximately perpendicular to that of the ethylenic group, and both the aromatic group planes are significantly twisted out of the ethylenic group plane. Crystal structures of methyl (E)-2,3-bis(3,4-dimethoxyphenyl)propenoate (space group P2₁/n with a = 8.1697(5), b = 11.3882(9), c = 19.7766(9) Å, = 90.058(4)°, V = 1840.0(2) ų, and Z = 4), monoclinic methyl (Z)-2,3-bis(3,4-dimethoxyphenyl)propenoate (space group P2₁/n with a = 11.183(2), b = 5.640(2), c = 29.737(7) Å, = 99.19(2)°, V = 1851.4(9) ų, and Z = 4), and orthorhombic methyl (Z)-2,3-bis(3,4-dimethoxyphenyl)propenoate (space group P2₁2₁2₁ with a = 8.849(4), b = 24.288(9), c = 8.734(3) Å, V = 1877(1) ų, and Z = 4) are reported.     

Are the Elements Elementary? Nineteenth-Century Chemical and Spectroscopical Answers

We analyze the role and influence of a tradition of research linked to the concept of primary matter in nineteenth-century studies on the nature of the elements.The suggestion of William Prout (1785-1850) in 1816 that the atomic weights of pure chemical elements are whole numbers and multiples of the atomic weight of hydrogen, taken as unity, was met with serious confutations,which in turn prompted several attempts to save Prouts hypothesis.We discuss these attempts in detail and the objections raised against them, for instance by Dmitry Ivanovich Mendeleev (1834-1907). We pay particular attention to the use of spectroscopy as a method for proving the existence of elementary forms of matter inside atoms. Leaders in this field of research were two English scientists, the astrophysicist Norman Lockyer (1836-1920) and the chemist William Crookes (1832- 1919). Both of their approaches involved the idea of primary matter. However, while Crookess approach proved to be incorrect, Lockyers ideas survived for several years and supported the discovery of the electron by J.J.Thomson (1856-1940).     

On the commutator of the Marcinkiewicz integral

boundedness is considered for the commutator of higher-dimensional Marcinkiewicz integral. Some conditions implying the and the boundedness for the commutator of the Marcinkiewicz integral are obtained.     

Pseudo-Anosov Flows and Incompressible Tori

We study incompressible tori in 3-manifolds supporting pseudo-Anosov flows and more generally ZZ subgroups of the fundamental group of such a manifold. If no element in this subgroup can be represented by a closed orbit of the pseudo-Anosov flow, we prove that the flow is topologically conjugate to a suspension of an Anosov diffeomorphism of the torus. In particular it is non singular and is an Anosov flow. It follows that either a pseudo-Anosov flow is topologically conjugate to a suspension Anosov flow, or any immersed incompressible torus can be realized as a free homotopy from a closed orbit of the flow to itself. The key tool is an analysis of group actions on non-Hausdorff trees, also known as R-order trees – we produce an invariant axis in the free action case. An application of these results is the following: suppose the manifold has an R-covered foliation transverse to a pseudo-Anosov flow. If the flow is not an R-covered Anosov flow, then it follows that the manifold is atoroidal.     

Shapley value for constant-sum games

It is proved that Youngs [4] axiomatization for the Shapley value by marginalism, efficiency, and symmetry is still valid for the Shapley value defined on the class of nonnegative constant-sum games with nonzero worth of grand coalition and on the entire class of constant-sum games as well.The research was supported by NWO (The Netherlands Organization for Scientific Research) grant NL-RF 047-008-010.I am thankful to Theo Driessen, Natalia Naumova and Elena Yanovskaya for interesting discussions and comments. The useful remarks of two anonymous referees are also appreciated.     

On finding curb sets in extensive games

We characterize strategy sets that are closed under rational behavior (curb) in extensive games of perfect information and finite horizon. It is shown that any such game possesses only one minimal curb set, which necessarily includes all its subgame perfect Nash equilibria. Applications of this result are twofold. First, it lessens computational burden while computing minimal curb sets. Second, it implies that the profile of subgame perfect equilibrium strategies is always stochastically stable in a certain class of games.I am grateful to J. Kamphorst, G. van der Laan and X. Tieman, who commented on the earlier versions of the paper. I also thank an anonymous referee and an associate editor for their helpful remarks. The usual disclaimer applies.     

On a Theorem of Holický and Zelený Concerning Borel Maps Without σ-Compact Fibers

The paper is concerned with a recent very interesting theorem obtained by Holický and Zelený. We provide an alternative proof avoiding games used by Holický and Zelený and give some generalizations to the case of set-valued mappings.