Thermal response of a PVCL–HA conjugate

The synthesis and self‐assembling of a thermoresponsive conjugate of hyaluronic acid (HA) and poly(N‐vinylcaprolactam) (PVCL) is reported. Both polymers were end functionalized: HA via reductive amination, thereby introducing an azide endgroup to the chain end, and PVCL via thioetherification to introduce a propargyl group. The two were coupled with a copper assisted “click” reaction into a bioconjugate composed of HA blocks with the molar mass 3,600 g mol^?1 (1618 saccharide units) and PVCL blocks of 3,500 g mol^?1 (～25 repeating units). The cloud point temperature measured by transmittance was 50–51 °C in water. The calorimetrically observed phase transition temperature of PVCL in the conjugate increased by 2 °C to 47.7 °C, whereas the enthalpy of the phase transition was unaffected by the conjugation. HA‐PVCL conjugate self‐assembles in water upon heating into monodisperse, colloidally stable, hollow spherical particles whose size may be tuned with the heating rate of the solution. Slow and fast heating resulted in vesicles with the hydrodynamic radii of 443 or 275 nm, respectively. The heating rate did not, however, affect the cloud point. Salt did not noticeably affect the size of the polymer particles, presumably because of interactions between the HA and PVCL blocks. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 425–436     

Vekua Systems in Hyperbolic Harmonic Analysis

In this paper we consider the solutions of the equation \({\mathcal {M}}_\kappa f=0\), where \({\mathcal {M}}_\kappa \) is the so called modifier Dirac operator acting on functions \(f\) defined in the upper half-space and taking values in the Clifford algebra. We look for solutions \(f(\underline{x},x_{n})\) where the first variable is invariant under rotations. A special type of solution is generated by the so called spherical monogenic functions. These solutions may be characterize by a Vekua-type system and this system may be solved using Bessel functions. We will see that the solution of the equation \({\mathcal {M}}_\kappa f=0\) in this case will be a product of Bessel functions.     

On s-Reflexive Spaces and Continuous Selections

This paper deals with the s-reflexive spaces introduced by Yang and Zhao. The authors prove that every s-reflexive Hausdorff space is zero-dimensional, and indicate a close relationship between the theory of s-reflexive spaces and that of continuous selections. Several examples relating to s-reflexivity are given.     

Quantification of triacylglycerol regioisomers by ultra‐high‐performance liquid chromatography and ammonia negative ion atmospheric pressure chemical ionization tandem mass spectrometry

The regioisomer composition of triacylglycerols (TAGs) in various vegetable oils was determined with a new liquid chromatography/tandem mass spectrometry (LC/MS/MS method). A direct inlet ammonia negative ion chemical ionization (NICI) MS/MS method was improved by adapting it to LC negative ion (NI) atmospheric pressure chemical ionization (APCI) MS/MS system using ammonia as nebulizer gas. The method is based on the preferential formation of [M–H–RCOOH–100]^? ions during collision‐induced dissociation by loss of sn‐1/3 fatty acids from [M–H]^? ions. Calibration curves were created from nine reference TAGs: Ala/L/L, Gla/L/L, L/L/O, L/O/O, P/O/O, P/P/O, Po/Po/V, Po/Po/O, and C/O/O. The calibration curves were used to quantify the regioisomer compositions of selected TAGs in rapeseed oil, sunflower seed oil, palm oil, black currant seed oil, and sea buckthorn pulp oil. The method discriminates the different regioisomers and the results obtained by this method were in good agreement with previous results. This proves that this new method can be used for the determination of regiospecific distribution of fatty acids in TAGs. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of adenylyl-(3'----5')-guanosine and some analogues as probes to explore the molecular mechanism of stimulation of influenza virus RNA polymerase

Influenza virus mRNA synthesis is primed by a capped oligonucleotide which is cleaved off from a cellular mRNA by a viral protein. The dinucleotide A3'p5'G can be used as a primer for the viral RNA polymerase mediated RNA synthesis in a cell-free system. Analogues of A3'p5'G have therefore been synthesized using the phosphotriester approach, and their priming ability for the influenza virus mRNA synthesis has been determined. An absence of the 2'-hydroxyl function in the guanosine residue in the dinucleotide, as in A3'p5'dG, drastically decreased its priming ability. Similarly, an alteration of the 3'----5' phosphate linkage to a 2'----5' phosphodiester linkage affected the priming ability quite severely. However a dinucleotide, with the 2'-hydroxyl function omitted in the adenosine moiety, as in dA3'p5'G, could still stimulate the mRNA synthesis. None of the modified dinucleotides inhibited A3'p5'G or globin mRNA primed influenza mRNA synthesis.     

Pairwise effects of chlorine substituents on the 13C NMR chemical shifts of dichlorobicyclo[2.2.1]heptanes (norbornanes)

The ¹³C NMR spectra of nine dichlorinated bicyclo[2.2.1]heptanes (norbornanes) have been measured and assigned. The pairwise effects of chlorine substituents which cause deviations from the additivity of single-substituent effects were investigated and are discussed. The largest effect found is the high-field shift of carbons bearing vicinal cis substituents. In the case of geminal substitution deviations from additivity were found to be to low field and large in the γ, smaller in the β and negligible in the α chemical shifts. The observed deviations for 1,3-disubstituted cases vary from ?3.2 to +1.1 ppm at different carbons, allowing no simple explanation. Replacement of α-hydrogen in a diaxial 1,3-arrangement by CH₃, OH or CI causes the single substituent effect, namely the γ_a effect, to change considerably.     

Rotation Planar Extraction and Medium-Pressure Solid—Liquid Extraction of Onion (Allium cepa)

JPC – Journal of Planar Chromatography – Modern TLC - Extraction of onion (Allium cepa L.) with 80:20 (v/v) methanol—water in water by rotation planar extraction (RPE) and medium-...     

When is a Volterra space Baire?

In this paper, we study the problem when a Volterra space is Baire. It is shown that every stratifiable Volterra space is Baire. This answers affirmatively a question of Gruenhage and Lutzer in [G. Gruenhage, D. Lutzer, Baire and Volterra spaces, Proc. Amer. Math. Soc. 128 (2000) 3115-3124]. Further, it is established that a locally convex topological vector space is Volterra if and only if it is Baire; and the weak topology of a topological vector space fails to be Baire if the dual of the space contains an infinite linearly independent pointwise bounded subset.