Comparative evaluation of bioactivity of crystalline trypsin for drying by Fourier-transformed infrared spectroscopy

The purpose of this study was to evaluate the enzymatic stability of colloidal trypsin powder during heating in a solid-state by using Fourier transform infrared (FT-IR) spectra with chemoinformatics and generalized two-dimensional (2D) correlation spectroscopy. Colloidal crystalline trypsin powders were heated using differential scanning calorimetry. The enzymatic activity of trypsin was assayed by the kinetic degradation method. Spectra of 10 calibration sample sets were recorded three times with a FT-IR spectrometer. The maximum intensity at 1634 cm⁻¹ of FT-IR spectra and enzymatic activity of trypsin decreased as the temperature increased. The FT-IR spectra of trypsin samples were analyzed by a principal component regression analysis (PCR). A plot of the calibration data obtained was made between the actual and predicted trypsin activity based on a two-component model with γ² = 0.962. On the other hand, a 2D method was applied to FT-IR spectra of heat-treated trypsin. The result was consistent with that of the chemoinformetrical method. The results for deactivation of colloidal trypsin powder by heat-treatment indicated that nano-structure of crystalline trypsin changed by heating reflecting that the β-sheet was mainly transformed, since the peak at 1634 cm⁻¹ decreased with dehydration. The FT-IR chemoinformetrical method allows for a solid-state quantitative analysis of the bioactivity of the bulk powder of trypsin during drying.     

A Peanut‐Shaped Polyaromatic Capsule: Solvent‐Dependent Transformation and Electronic Properties of a Non‐Contacted Fullerene Dimer

Synthesis of molecular containers capable of incorporating multiple fullerenes remains challenging. Reported here is that room‐temperature mixing of metal ions with W‐shaped bispyridine ligands featuring polyaromatic panels results in the quantitative formation of a peanut‐shaped M₂L₄ capsule. The capsule reversibly converts into two molecules of an ML₂ double tube in response to changes in the solvent. Notably, the capsule allows the incorporation of two fullerene molecules into the connected two spherical cavities at room temperature. The close proximity yet non‐contact of the encapsulated C₆₀ molecules, with a separation of 6.4 Å, was revealed by X‐ray crystallographic analysis. The resultant, unusual fullerene dimer undergoes sequential reduction within the capsule to generate (C₆₀^.?)₂, C₆₀^.??C₆₀^2?, and (C₆₀^2?)₂ species. Furthermore, temperature‐controlled stepwise incorporation of two C₆₀ molecules into the capsule is demonstrated.     

SR-PES and STM observation of metastable chemisorption state of oxygen on Si(1 1 0)-16 × 2 surface

Initial adsorption of oxygen molecules on the Si(1 1 0)-16 × 2 surface and subsequent modification of the bonding states induced by mild (300 °C) annealing have been studied by synchrotron-radiation photoemission spectroscopy and scanning-tunneling microscopy. It has been shown that upon annealing, the intensity and the energy positions of the Si 2p suboxide components shift towards the values characteristic for the thermal oxide. This indicates the presence of a metastable chemisorption state of oxygen on the Si(1 1 0)-16 × 2 surface.     

13C‐TmDOTA as versatile thermometer compound for solid‐state NMR of hydrated lipid bilayer membranes

Recent advances in solid‐state nuclear magnetic resonance (NMR) techniques, such as magic angle spinning and high‐power decoupling, have dramatically increased the sensitivity and resolution of NMR. However, these NMR techniques generate extra heat, causing a temperature difference between the sample in the rotor and the variable temperature gas. This extra heating is a particularly crucial problem for hydrated lipid membrane samples. Thus, to develop an NMR thermometer that is suitable for hydrated lipid samples, thulium‐1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetate (TmDOTA) was synthesized and labeled with ¹³C (i.e., ¹³C‐TmDOTA) to increase the NMR sensitivity. The complex was mixed with a hydrated lipid membrane, and the system was subjected to solid‐state NMR and differential scanning calorimetric analyses. The physical properties of the lipid bilayer and the quality of the NMR spectra of the membrane were negligibly affected by the presence of ¹³C‐TmDOTA, and the ¹³C chemical shift of the complex exhibited a large‐temperature dependence. The results demonstrated that ¹³C‐TmDOTA could be successfully used as a thermometer to accurately monitor temperature changes induced by ¹H decoupling pulses and/or by magic angle spinning and the temperature distribution of the sample inside the rotor. Thus, ¹³C‐TmDOTA was shown to be a versatile thermometer for hydrated lipid assemblies. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of fluorine-containing graft copolyamides by using condensation-type macromonomers

Fluorine-containing graft copolyamides were prepared from condensation-type macromonomers. Dicarboxyl-terminated poly(perfluoroalkylethyl acrylate) was prepared by radical chain transfer polymerization and copolycondensed with diamines and dicarboxylic acids in the presence of triphenylphosphine and pyridine. Nylon-6 films containing various amounts of the resulting graft copolyamides were obtained by heat pressing. Only 5 wt % of graft copolymers were sufficient to make nylon-6 surfaces water repellent.     

Trithallium hydrogen bis(sulfate), Tl3H(SO4)2, in the super‐ionic phase by X‐ray powder diffraction

The structure of trithallium hydrogen bis­(sulfate), Tl₃H(SO₄)₂, in the super‐ionic phase has been analyzed by Rietveld analysis of the X‐ray powder diffraction pattern. Atomic parameters based on the isotypic Rb₃H(SeO₄)₂ crystal in space group Rm in the super‐ionic phase were used as the starting model, because it has been shown from the comparison of thermal and electric properties in Tl₃H(SO₄)₂ and M₃H(SO₄)₂ type crystals (M = Rb, Cs or NH₄) that the room‐temperature Tl₃H(SO₄)₂ phase is isostructural with the high‐temperature Rm‐symmetry M₃H(SO₄)₂ crystals. The structure was determined in the trigonal space group Rm and the Rietveld refinement shows that an hydrogen‐bond O—­H?O separation is slightly shortened compared with O—H?O separations in isotypic M₃H(SeO₄)₂ crystals. In addition, it was found that the distortion of the SO₄ tetrahedra in Tl₃H(SO₄)₂ is less than that in isotypic crystals.     

Triad distributions of 1,1-diphenylethylene–methyl acrylate copolymer determined from NMR study

The triad distributions of 1,1-diphenylethylene (D)–methyl acrylate (M) copolymers have been determined from NMR measurements and examined according to the terminal and penultimate models of copolymerization theory. As expected from the diamagnetic shielding by the phenyl rings of the nearest D units, the methoxy proton resonances were found to appear as three resolved peaks at 6.4–6.6 τ, 6.7–7.0 τ, and 7.2 τ, and have been assigned to the central M units of the triads MMM, MMD or DMM and DMD, respectively. The copolymer composition and the triad distributions observed are shown to agree better with the terminal model with the methyl acrylate reactivity ratio of 0.092 ± 0.010 than with the penultimate model.     

Correlation of cationic copolymerization parameters of cyclic ethers,formals, and esters

Carefully determined cationic copolymerization parameters of cyclic ethers, formals, and esters are collected. Relative reactivity correlates with basicity and free energy. Further correlations of the copolymerization parameters for styrene, the effect of promoters, and the known mechanism of hydrolysis permitted a decision between the carbonium ion (including acylium ion) or the oxonium ion as the active intermediate of the propagation. Structural features which promote depropagation are identified. Equations describing these possibilities were derived and briefly discussed. Catalyst and solvent effects limited the correlation possibilities.